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HttpLuaModuleZh

Revision as of 07:24, 29 December 2011 by Smallfish (Talk)

Contents

名称

英文文档地址:http://wiki.nginx.org/HttpLuaModule

ngx_lua - Embed the power of Lua into Nginx

此模块属第三方扩展,不在Nginx源码中。 安装介绍

状态

模块处于持续更新状态,并可用于生产环境。

版本

本文档基于 ngx_lua v0.3.1rc42 版本,最后更新2011-12-24。

示例

    # 设置纯Lua扩展库PATH(';;' is the default path):
    lua_package_path '/foo/bar/?.lua;/blah/?.lua;;';
 
    # 设置C扩展Lua模块,CPATH(can also use ';;'):
    lua_package_cpath '/bar/baz/?.so;/blah/blah/?.so;;';
 
    server {
        location /inline_concat {
            # default_type指令设置默认MIME头:
            default_type 'text/plain';
 
            set $a "hello";
            set $b "world";
            # 内嵌lua代码
            set_by_lua $res "return ngx.arg[1]..ngx.arg[2]" $a $b;
            echo $res;
        }
 
        location /rel_file_concat {
            set $a "foo";
            set $b "bar";
            # script path relative to nginx prefix
            # $ngx_prefix/conf/concat.lua contents:
            #
            #    return ngx.arg[1]..ngx.arg[2]
            #
            set_by_lua_file $res conf/concat.lua $a $b;
            echo $res;
        }
 
        location /abs_file_concat {
            set $a "fee";
            set $b "baz";
            # absolute script path not modified
            set_by_lua_file $res /usr/nginx/conf/concat.lua $a $b;
            echo $res;
        }
 
        location /lua_content {
            # MIME type determined by default_type:
            default_type 'text/plain';
 
            content_by_lua "ngx.say('Hello,world!')"
        }
 
         location /nginx_var {
            # MIME type determined by default_type:
            default_type 'text/plain';
 
            # try access /nginx_var?a=hello,world
            content_by_lua "ngx.print(ngx.var['arg_a'], '\\n')";
        }
 
        location /request_body {
             # force reading request body (default off)
             lua_need_request_body on;
             client_max_body_size 50k;
             client_body_buffer_size 50k;
 
             content_by_lua 'ngx.print(ngx.var.request_body)';
        }
 
        # transparent non-blocking I/O in Lua via subrequests
        location /lua {
            # MIME type determined by default_type:
            default_type 'text/plain';
 
            content_by_lua '
                local res = ngx.location.capture("/some_other_location")
                if res.status == 200 then
                    ngx.print(res.body)
                end';
        }
 
        # GET /recur?num=5
        location /recur {
            # MIME type determined by default_type:
            default_type 'text/plain';
 
            content_by_lua '
               local num = tonumber(ngx.var.arg_num) or 0
 
               if num > 50 then
                   ngx.say("num too big")
                   return
               end
 
               ngx.say("num is: ", num)
 
               if num > 0 then
                   res = ngx.location.capture("/recur?num=" .. tostring(num - 1))
                   ngx.print("status=", res.status, " ")
                   ngx.print("body=", res.body)
               else
                   ngx.say("end")
               end
               ';
        }
 
        location /foo {
            rewrite_by_lua '
                res = ngx.location.capture("/memc",
                    { args = { cmd = 'incr', key = ngx.var.uri } }
                )
            ';
 
            proxy_pass http://blah.blah.com;
        }
 
        location /blah {
            access_by_lua '
                local res = ngx.location.capture("/auth")
 
                if res.status == ngx.HTTP_OK then
                    return
                end
 
                if res.status == ngx.HTTP_FORBIDDEN then
                    ngx.exit(res.status)
                end
 
                ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
            ';
 
            # proxy_pass/fastcgi_pass/postgres_pass/...
        }
 
        location /mixed {
            rewrite_by_lua_file /path/to/rewrite.lua;
            access_by_lua_file /path/to/access.lua;
            content_by_lua_file /path/to/content.lua;
        }
 
        # use nginx var in code path
        # WARN: contents in nginx var must be carefully filtered,
        # otherwise there'll be great security risk!
        location ~ ^/app/(.+) {
                content_by_lua_file /path/to/lua/app/root/$1.lua;
        }
 
        location / {
           lua_need_request_body on;
 
           client_max_body_size 100k;
           client_body_buffer_size 100k;
 
           access_by_lua '
               -- check the client IP addr is in our black list
               if ngx.var.remote_addr == "132.5.72.3" then
                   ngx.exit(ngx.HTTP_FORBIDDEN)
               end
 
               -- check if the request body contains bad words
               if ngx.var.request_body and
                        string.match(ngx.var.request_body, "fsck")
               then
                   return ngx.redirect("/terms_of_use.html")
               end
 
               -- tests passed
           ';
 
           # proxy_pass/fastcgi_pass/etc settings
        }
    }

Description

This module embeds Lua, via the standard interpreter or LuaJIT, into Nginx and by leveraging Nginx subrequests, allows the integration of the powerful Lua threads ( Lua coroutines) into the Nginx event model.

Unlike Apache's mod_lua and Lighttpd's mod_magnet, Lua code executed using this module can be 100% non-blocking on network traffic as long as either of the ngx.location.capture or ngx.location.capture_multi interfaces are used to handle requests to upstream services such as mysql, postgresql, memcached, redis, or upstream http web services. (see HttpDrizzleModule, ngx_postgres, HttpMemcModule, HttpRedis2Module and HttpProxyModule modules for details).

The Lua interpreter or LuaJIT instance is shared across all the requests in a single nginx worker process but request contexts are segregated using lightweight Lua coroutines. Loaded Lua modules persist at the nginx worker process level resulting in a small memory footprint even when under heavy loads.

Directives

lua_code_cache

syntax: lua_code_cache on | off

default: lua_code_cache on

context: main, server, location, location if

Enable or disable the Lua code cache for set_by_lua_file, content_by_lua_file, rewrite_by_lua_file, and access_by_lua_file, and also force Lua module reloading on a per-request basis.

The Lua files referenced in set_by_lua_file, content_by_lua_file, access_by_lua_file, and rewrite_by_lua_file will not be cached at all, and Lua's package.loaded table will be cleared at the entry point of every request (such that Lua modules will not be cached either). With this in place, developers can follow the PHP way, i.e., edit-and-refresh.

Please note however, that Lua code inlined into nginx.conf such as those specified by set_by_lua, content_by_lua, access_by_lua, and rewrite_by_lua will always be cached because only the Nginx config file parser can correctly parse the nginx.conf file and the only ways to to reload the config file are to send a HUP signal or to restart Nginx.

The ngx_lua module currently does not support the "stat" mode like Apache's mod_lua does but this is planned for implementation in the future.

Disabling the Lua code cache is strongly discouraged for production use and should only be used during development as it has a significant impact on overall performance. In addition, race conditions when reloading Lua modules are common for concurrent requests when the code cache is disabled.

lua_regex_cache_max_entries

syntax: lua_regex_cache_max_entries <num>

default: lua_regex_cache_max_entries 1024

context: http

Specifies the maximum number of entries allowed in the worker process level compiled regex cache.

The regular expressions used in ngx.re.match, ngx.re.gmatch, ngx.re.sub, and ngx.re.gsub will be cached within this cache if the regex option o (i.e., compile-once flag) is specified.

The default number of entries allowed is 1024 and when this limit is reached, new regexes will not be cached (as if the o option was not specified) and there will be one, and only one, warning in the error.log file:

    2011/08/27 23:18:26 [warn] 31997#0: *1 lua exceeding regex cache max entries (1024), ...

You should not activate the o option for regexes (and/or replace string arguments for ngx.re.sub and ngx.re.gsub) that are generated on the fly and give rise to infinite variations to avoid hitting the specified limit.

lua_package_path

syntax: lua_package_path <lua-style-path-str>

default: The content of LUA_PATH environ variable or Lua's compiled-in defaults.

context: main

Sets the Lua module search path used by scripts specified by set_by_lua, content_by_lua and others. The path string is in standard Lua path form, and ;; can be used to stand for the original path.

lua_package_cpath

syntax: lua_package_cpath <lua-style-cpath-str>

default: The content of LUA_CPATH environ variable or Lua's compiled-in defaults.

context: main

Sets the Lua C-module search path used by scripts specified by set_by_lua, content_by_lua and others. The cpath string is in standard Lua cpath form, and ;; can be used to stand for the original cpath.

set_by_lua

syntax: set_by_lua $res <lua-script-str> [$arg1 $arg2 ...]

context: main, server, location, server if, location if

phase: rewrite

Execute user code specified by <lua-script-str> with input arguments $arg1 $arg2 ..., and set the script's return value to $res in string form. The code in <lua-script-str> can retrieve input arguments from the ngx.arg table (index starts from 1 and increases sequentially) and the lua code may make API calls.

The set_by_lua directive is designed to execute short, fast running code blocks as the Nginx event loop is blocked during code execution. Time consuming code sequences should therefore be avoided.

Note that set_by_lua can only output a value to a single Nginx variable at a time but a workaround is possible by using the ngx.var.VARIABLE interface. For example,

    location /foo {
        set $diff ''; # we have to predefine the $diff variable here
 
        set_by_lua $sum '
            local a = 32
            local b = 56
 
            ngx.var.diff = a - b;  -- write to $diff directly
            return a + b;          -- return the $sum value normally
        ';
 
        echo "sum = $sum, diff = $diff";
    }

This directive can be freely mixed with all the directives of HttpRewriteModule, HttpSetMiscModule, and HttpArrayVarModule. All of these directives will run in exactly the same order that they are written in the config file. For example,

    set $foo 32;
    set_by_lua $bar 'tonumber(ngx.var.foo) + 1';
    set $baz "bar: $bar";  # $baz == "bar: 33"

This directive requires the ngx_devel_kit module.

set_by_lua_file

syntax: set_by_lua_file $res <path-to-lua-script-file> [$arg1 $arg2 ...]

context: main, server, location, server if, location if

phase: rewrite

Equivalent to set_by_lua, except that the file specified by <path-to-lua-script-file> contains the lua code to be executed.

When the Lua code cache is on (default state), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time you modify the Lua source file. You can temporarily disable the Lua code cache during development by switching lua_code_cache off in your nginx.conf to avoid reloading Nginx.

This directive requires the ngx_devel_kit module.

content_by_lua

syntax: content_by_lua <lua-script-str>

context: location, location if

phase: content

Acts as a "content handler" and executes lua code string specified in <lua-script-str> for every request. The lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).

Do not use this directive and other content handler directives in the same location. For example, this directive and the proxy_pass directive should not be used in the same location.

content_by_lua_file

syntax: content_by_lua_file <path-to-lua-script-file>

context: location, location if

phase: content

Equivalent to content_by_lua, except that the file specified by <path-to-lua-script-file> contains the lua code to be executed.

Nginx variables can be used in the <path-to-lua-script-file> string to provide flexibility. This however carries some risks and is not ordinarily recommended.

When the Lua code cache is on (default state), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time you modify the Lua source file. You can temporarily disable the Lua code cache during development by switching lua_code_cache off in your nginx.conf to avoid reloading Nginx.

rewrite_by_lua

syntax: rewrite_by_lua <lua-script-str>

context: http, server, location, location if

phase: post-rewrite

Acts as a rewrite phase handler and executes lua code string specified in <lua-script-str> for every request. The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).

Note that this handler always runs after the standard HttpRewriteModule. So the following will work as expected:

   location /foo {
       set $a 12; # create and initialize $a
       set $b ""; # create and initialize $b
       rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1';
       echo "res = $b";
   }

because set $a 12 and set $b "" run before rewrite_by_lua.

On the other hand, the following will not work as expected:

    ?  location /foo {
    ?      set $a 12; # create and initialize $a
    ?      set $b ''; # create and initialize $b
    ?      rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1';
    ?      if ($b = '13') {
    ?         rewrite ^ /bar redirect;
    ?         break;
    ?      }
    ?
    ?      echo "res = $b";
    ?  }

because if runs before rewrite_by_lua even if it is put after rewrite_by_lua in the config.

The right way of doing this is as follows:

    location /foo {
        set $a 12; # create and initialize $a
        set $b ''; # create and initialize $b
        rewrite_by_lua '
            ngx.var.b = tonumber(ngx.var.a) + 1
            if tonumber(ngx.var.b) == 13 then
                return ngx.redirect("/bar");
            end
        ';
 
        echo "res = $b";
    }

It is worth mentioning that, the ngx_eval module can be approximately implemented by rewrite_by_lua. For example,

    location / {
        eval $res {
            proxy_pass http://foo.com/check-spam;
        }
 
        if ($res = 'spam') {
            rewrite ^ /terms-of-use.html redirect;
        }
 
        fastcgi_pass ...;
    }

can be implemented in terms of ngx_lua like this

    location = /check-spam {
        internal;
        proxy_pass http://foo.com/check-spam;
    }
 
    location / {
        rewrite_by_lua '
            local res = ngx.location.capture("/check-spam")
            if res.body == "spam" then
                ngx.redirect("/terms-of-use.html")
            end
        ';
 
        fastcgi_pass ...;
    }

Just as any other rewrite phase handlers, rewrite_by_lua also runs in subrequests.

Note that when calling ngx.exit(ngx.OK) within a rewrite_by_lua handler, the nginx request processing control flow will still continue to the content handler. To terminate the current request from within a rewrite_by_lua handler, calling ngx.exit with status >= 200 (ngx.HTTP_OK) and status < 300 (ngx.HTTP_SPECIAL_RESPONSE) for successful quits and ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR) (or its friends) for failures.

If the HttpRewriteModule's rewrite directive is used to change the URI and initiate location re-lookups (internal redirections), then any rewrite_by_lua or rewrite_by_lua_file code sequences within the current location will not be executed. For example,

    location /foo {
        rewrite ^ /bar;
        rewrite_by_lua 'ngx.exit(503)';
    }
    location /bar {
        ...
    }

Here the Lua code ngx.exit(503) will never run. This will be the case if rewrite ^ /bar last is used as this will similarly initiate an internal redirection. If the break modifier is used instead, there will be no internal rediction and the rewrite_by_lua code will be executed.

rewrite_by_lua_file

syntax: rewrite_by_lua_file <path-to-lua-script-file>

context: http, server, location, location if

phase: post-rewrite

Equivalent to rewrite_by_lua, except that the file specified by <path-to-lua-script-file> contains the Lua code to be executed.

Nginx variables can be used in the <path-to-lua-script-file> string to provide flexibility. This however carries some risks and is not ordinarily recommended.

When the Lua code cache is on (default state), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time you modify the Lua source file. You can temporarily disable the Lua code cache during development by switching lua_code_cache off in your nginx.conf to avoid reloading Nginx.

access_by_lua

syntax: access_by_lua <lua-script-str>

context: http, server, location, location if

phase: post-access

Acts as an access phase handler and executes lua code string specified in <lua-script-str> for every request. The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).

Note that this handler always runs after the standard HttpAccessModule. So the following will work as expected:

    location / {
        deny    192.168.1.1;
        allow   192.168.1.0/24;
        allow   10.1.1.0/16;
        deny    all;
 
        access_by_lua '
            local res = ngx.location.capture("/mysql", { ... })
            ...
        ';
 
        # proxy_pass/fastcgi_pass/...
    }

That is, if a client IP address is in the blacklist, it will be denied before the MySQL query for more complex authentication is executed by access_by_lua.

It is worth mentioning that the ngx_auth_request module can be approximated using access_by_lua:

    location / {
        auth_request /auth;
 
        # proxy_pass/fastcgi_pass/postgres_pass/...
    }

can be implemented in terms of ngx_lua like this

    location / {
        access_by_lua '
            local res = ngx.location.capture("/auth")
 
            if res.status == ngx.HTTP_OK then
                return
            end
 
            if res.status == ngx.HTTP_FORBIDDEN then
                ngx.exit(res.status)
            end
 
            ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
        ';
 
        # proxy_pass/fastcgi_pass/postgres_pass/...
    }

As with other access phase handlers, access_by_lua will not run in subrequests.

Note that when calling ngx.exit(ngx.OK) within a access_by_lua handler, the nginx request processing control flow will still continue to the content handler. To terminate the current request from within a access_by_lua handler, calling ngx.exit with status >= 200 (ngx.HTTP_OK) and status < 300 (ngx.HTTP_SPECIAL_RESPONSE) for successful quits and ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR) (or its friends) for failures.

access_by_lua_file

syntax: access_by_lua_file <path-to-lua-script-file>

context: http, server, location, location if

phase: post-access

Equivalent to access_by_lua, except that the file specified by <path-to-lua-script-file> contains the Lua code to be executed.

Nginx variables can be used in the <path-to-lua-script-file> string to provide flexibility. This however carries some risks and is not ordinarily recommended.

When the Lua code cache is on (default state), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time you modify the Lua source file. You can temporarily disable the Lua code cache during development by switching lua_code_cache off in your nginx.conf to avoid reloading Nginx.

header_filter_by_lua

syntax: header_filter_by_lua <lua-script-str>

context: http, server, location, location if

phase: output-header-filter

Uses Lua code specified in <lua-script-str> to define an output header filter. Note that the following API functions are currently disabled within this context:

Here is an example of overriding a response header (or adding one if absent) in our Lua header filter:

    location / {
        proxy_pass http://mybackend;
        header_filter_by_lua 'ngx.header.Foo = "blah"';
    }

This directive was first introduced in the v0.2.1rc20 release.

header_filter_by_lua_file

syntax: header_filter_by_lua_file <path-to-lua-script-file>

context: http, server, location, location if

phase: output-header-filter

Equivalent to header_filter_by_lua, except that the file specified by <path-to-lua-script-file> contains the lua code to be executed.

This directive was first introduced in the v0.2.1rc20 release.

lua_need_request_body

syntax: lua_need_request_body <on|off>

default: off

context: main | server | location

phase: depends on usage

Determines whether to force the request body data to be read before running rewrite/access/access_by_lua* or not. The Nginx core does not read the client request body by default and if request body data is required, then this directive should be turned on or the ngx.req.read_body function should be called within the Lua code.

To read the request body data within the $request_body variable, client_body_buffer_size must have the same value as client_max_body_size. Because when the content length exceeds client_body_buffer_size but less than client_max_body_size, Nginx will automatically buffer the data into a temporary file on the disk, which will lead to empty value in the $request_body variable.

If the current location includes rewrite_by_lua or rewrite_by_lua_file directives, then the request body will be read just before the rewrite_by_lua or rewrite_by_lua_file code is run (and also at the rewrite phase). Similarly, if only content_by_lua is specified, the request body will not be read until the content handler's Lua code is about to run (i.e., the request body will be read during the content phase).

It is recommended however, to use the ngx.req.read_body and ngx.req.discard_body functions for finer control over the request body reading process instead.

This also applies to access_by_lua and access_by_lua_file.

lua_shared_dict

syntax: lua_shared_dict <name> <size>

default: no

context: main

phase: depends on usage

Declares a shared memory zone, <name>, to serve as storage for the shm-based Lua dictionary ngx.shared.<name>.

The <size> argument accepts size units such as k and m:

    http {
        lua_shared_dict dogs 10m;
        ...
    }

See ngx.shared.DICT for details.

This directive was first introduced in the v0.3.1rc22 release.

Nginx API for Lua

Introduction

The various *_by_lua and *_by_lua_file configuration directives serve as gateways to the Lua API within the nginx.conf file. The Lua API described below can only be called within the user Lua code run in the context of these configuration directives.

The API is exposed to Lua in the form of two standard packages ngx and ndk. These packages are in the default global scope within ngx_lua and can also be introduced to external Lua modules by using the package.seeall option:

    module("my_module", package.seeall)
 
    function say(a) ngx.say(a) end

Alternatively, they can be imported to external Lua modules by using file scoped local Lua variables:

    local ngx = ngx
    module("my_module")
 
    function say(a) ngx.say(a) end

It is also possible to directly require the packages:

    local ngx = require "ngx"
    local ndk = require "ndk"

The ability to require these packages was introduced in the v0.2.1rc19 release.

Network I/O operations in user code should only be done through the Lua API calls as the Nginx event loop may be blocked and performance may drop off dramatically otherwise. Minor disk file operations may be done via Lua's standard io and file libraries but these should be avoided wherever possible as these also block the Nginx process. Delegating all network and disk I/O operations to Nginx subrequests (via the ngx.location.capture method and similar) is strongly recommended for maximum performance.

ngx.arg

syntax: val = ngx.arg[index]

context: set_by_lua*

Index the input arguments to the set_by_lua and set_by_lua_file directives:

    value = ngx.arg[n]

Here is an example

    location /foo {
        set $a 32;
        set $b 56;
 
        set_by_lua $res
            'return tonumber(ngx.arg[1]) + tonumber(ngx.arg[2])'
            $a $b;
 
        echo $sum;
    }

that outputs 88, the sum of 32 and 56.

ngx.var.VARIABLE

syntax: ngx.var.VAR_NAME

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Read and write Nginx variable values.

    value = ngx.var.some_nginx_variable_name
    ngx.var.some_nginx_variable_name = value

Note that you can only write to nginx variables that are already defined. For example:

    location /foo {
        set $my_var ''; # this line is required to create $my_var at config time
        content_by_lua '
            ngx.var.my_var = 123;
            ...
        ';
    }

That is, nginx variables cannot be created on-the-fly.

Some special nginx variables like $args and $limit_rate can be assigned a value, some are not, like $arg_PARAMETER.

Nginx regex group capturing variables $1, $2, $3, and etc, can be read by this interface as well, by writing ngx.var[1], ngx.var[2], ngx.var[3], and etc.

Setting nil values to ngx.var.Foo will effectively make Nginx variable $Foo undefined. For instance,

    ngx.var.args = nil

Core constants

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

  ngx.OK (0)
  ngx.ERROR (-1)
  ngx.AGAIN (-2)
  ngx.DONE (-4)

They take the same values of NGX_OK, NGX_AGAIN, NGX_DONE, NGX_ERROR, and etc. But now only ngx.exit only take two of these values, i.e., NGX_OK and NGX_ERROR.

HTTP method constants

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

  ngx.HTTP_GET
  ngx.HTTP_HEAD
  ngx.HTTP_PUT
  ngx.HTTP_POST
  ngx.HTTP_DELETE

These constants are usually used in ngx.location.catpure and ngx.location.capture_multi method calls.

HTTP status constants

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

  value = ngx.HTTP_OK (200)
  value = ngx.HTTP_CREATED (201)
  value = ngx.HTTP_SPECIAL_RESPONSE (300)
  value = ngx.HTTP_MOVED_PERMANENTLY (301)
  value = ngx.HTTP_MOVED_TEMPORARILY (302)
  value = ngx.HTTP_SEE_OTHER (303)
  value = ngx.HTTP_NOT_MODIFIED (304)
  value = ngx.HTTP_BAD_REQUEST (400)
  value = ngx.HTTP_UNAUTHORIZED (401)
  value = ngx.HTTP_FORBIDDEN (403)
  value = ngx.HTTP_NOT_FOUND (404)
  value = ngx.HTTP_NOT_ALLOWED (405)
  value = ngx.HTTP_GONE (410)
  value = ngx.HTTP_INTERNAL_SERVER_ERROR (500)
  value = ngx.HTTP_METHOD_NOT_IMPLEMENTED (501)
  value = ngx.HTTP_SERVICE_UNAVAILABLE (503)
  value = ngx.HTTP_GATEWAY_TIMEOUT (504) (first added in the v0.3.1rc38 release)

Nginx log level constants

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

  ngx.STDERR
  ngx.EMERG
  ngx.ALERT
  ngx.CRIT
  ngx.ERR
  ngx.WARN
  ngx.NOTICE
  ngx.INFO
  ngx.DEBUG

These constants are usually used by the ngx.log method.

print

syntax: print(...)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Emit args concatenated to nginx's error.log file, with log level ngx.NOTICE and prefix lua print: .

It is equivalent to

    ngx.log(ngx.NOTICE, 'lua print: ', a, b, ...)

Lua nil arguments are accepted and result in literal "nil", and Lua booleans result in "true" or "false".

ngx.ctx

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

This table can be used to store per-request context data for Lua programmers.

This table has a liftime identical to the current request (just like Nginx variables). Consider the following example,

    location /test {
        rewrite_by_lua '
            ngx.say("foo = ", ngx.ctx.foo)
            ngx.ctx.foo = 76
        ';
        access_by_lua '
            ngx.ctx.foo = ngx.ctx.foo + 3
        ';
        content_by_lua '
            ngx.say(ngx.ctx.foo)
        ';
    }

Then GET /test will yield the output

    foo = nil
    79

That is, the ngx.ctx.foo entry persists across the rewrite, access, and content phases of a request.

Also, every request has its own copy, include subrequests, for example:

    location /sub {
        content_by_lua '
            ngx.say("sub pre: ", ngx.ctx.blah)
            ngx.ctx.blah = 32
            ngx.say("sub post: ", ngx.ctx.blah)
        ';
    }
 
    location /main {
        content_by_lua '
            ngx.ctx.blah = 73
            ngx.say("main pre: ", ngx.ctx.blah)
            local res = ngx.location.capture("/sub")
            ngx.print(res.body)
            ngx.say("main post: ", ngx.ctx.blah)
        ';
    }

Then GET /main will give the output

    main pre: 73
    sub pre: nil
    sub post: 32
    main post: 73

We can see that modification of the ngx.ctx.blah entry in the subrequest does not affect the one in its parent request. They do have two separate versions of ngx.ctx.blah per se.

Internal redirection will destroy the original request's ngx.ctx data (if any) and the new request will have an emptied ngx.ctx table. For instance,

    location /new {
        content_by_lua '
            ngx.say(ngx.ctx.foo)
        ';
    }
 
    location /orig {
        content_by_lua '
            ngx.ctx.foo = "hello"
            ngx.exec("/new")
        ';
    }

Then GET /orig will give you

    nil

rather than the original "hello" value.

Arbitrary data values can be inserted into this "matic" table, including Lua closures and nested tables. You can also register your own meta methods with it.

Overriding ngx.ctx with a new Lua table is also supported, for example,

    ngx.ctx = { foo = 32, bar = 54 }

ngx.location.capture

syntax: res = ngx.location.capture(uri, options?)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Issue a synchronous but still non-blocking Nginx Subrequest using uri.

Nginx subrequests provide a powerful way to make non-blocking internal requests to other locations configured with disk file directory or any other nginx C modules like ngx_proxy, ngx_fastcgi, ngx_memc, ngx_postgres, ngx_drizzle, and even ngx_lua itself and etc etc etc.

Also note that subrequests just mimic the HTTP interface but there is no extra HTTP/TCP traffic nor IPC involved. Everything works internally, efficiently, on the C level.

Subrequests are completely different from HTTP 301/302 redirection (via ngx.redirect) and internal redirection (via ngx.exec).

Here is a basic example:

    res = ngx.location.capture(uri)

Returns a Lua table with three slots (res.status, res.header, and res.body).

res.header holds all the response headers of the subrequest and it is a normal Lua table. For multi-value response headers, the value is a Lua (array) table that holds all the values in the order that they appear. For instance, if the subrequest response headers contains the following lines:

    Set-Cookie: a=3
    Set-Cookie: foo=bar
    Set-Cookie: baz=blah

Then res.header["Set-Cookie"] will be evaluted to the table value {"a=3", "foo=bar", "baz=blah"}.

URI query strings can be concatenated to URI itself, for instance,

    res = ngx.location.capture('/foo/bar?a=3&b=4')

Named locations like @foo are not allowed due to a limitation in the nginx core. Use normal locations combined with the internal directive to prepare internal-only locations.

An optional option table can be fed as the second argument, which support the options:

  • method
specify the subrequest's request method, which only accepts constants like ngx.HTTP_POST.
  • body
specify the subrequest's request body (string value only).
  • args
specify the subrequest's URI query arguments (both string value and Lua tables are accepted)
  • ctx
specify a Lua table to be the ngx.ctx table for the subrequest. It can be the current request's ngx.ctx table, which effectively make the parent and its subrequest to share exactly the same context table. This option was first introduced in the v0.3.1rc25 release.
  • vars
take a Lua table which holds the values to set the specified Nginx variables in the subrequest as this option's value. This option was first introduced in the v0.3.1rc31 release.
  • copy_all_vars
specify whether to copy over all the Nginx variable values of the current request to the subrequest in question. modifications of the nginx variables in the subrequest will not affect the current (parent) request. This option was first introduced in the v0.3.1rc31 release.
  • share_all_vars
specify whether to share all the Nginx variables of the subrequest with the current (parent) request. modifications of the Nginx variables in the subrequest will affect the current (parent) request.

Issuing a POST subrequest, for example, can be done as follows

    res = ngx.location.capture(
        '/foo/bar',
        { method = ngx.HTTP_POST, body = 'hello, world' }
    )

See HTTP method constants methods other than POST. The method option is ngx.HTTP_GET by default.

The args option can specify extra URI arguments, for instance,

    ngx.location.capture('/foo?a=1',
        { args = { b = 3, c = ':' } }
    )

is equivalent to

    ngx.location.capture('/foo?a=1&b=3&c=%3a')

that is, this method will automatically escape argument keys and values according to URI rules and concatenating them together into a complete query string. The format for the Lua table passed as the args argument is identical to the format used in the ngx.encode_args method.

The args option can also take plain query strings:

    ngx.location.capture('/foo?a=1',
        { args = 'b=3&c=%3a' } }
    )

This is functionally identical to the previous examples.

The share_all_vars option controls whether to share nginx variables among the current request and new subrequests. If this option is set to true, then the current request and associated subrequests will share the same Nginx variable scope. Hence, changes to Nginx variables made by a subrequest will affect the current request.

Care should be taken in using this option as variable scope sharing can have unexpected side effects. The args, vars, or copy_all_vars options are generally preferable instead.

This option is set to false by default

    location /other {
        set $dog "$dog world";                  
        echo "$uri dog: $dog";                    
    }                                     
 
    location /lua {
        set $dog 'hello';
        content_by_lua '
            res = ngx.location.capture("/other",
                { share_all_vars = true });
 
            ngx.print(res.body)
            ngx.say(ngx.var.uri, ": ", ngx.var.dog)
        ';  
    }

Accessing location /lua gives

    /other dog: hello world
    /lua: hello world

The copy_all_vars option provides a copy of the parent request's Nginx variables to subrequests when such subrequests are issued. Changes made to these variables by such subrequests will not affect the parent request or any other subrequests sharing the parent request's variables.

    location /other {
        set $dog "$dog world";
        echo "$uri dog: $dog";
    }
 
    location /lua {
        set $dog 'hello';
        content_by_lua '
            res = ngx.location.capture("/other",
                { copy_all_vars = true });
 
            ngx.print(res.body)
            ngx.say(ngx.var.uri, ": ", ngx.var.dog)
        ';
    }

Request GET /lua will give the output

    /other dog: hello world
    /lua: hello

Note that if both share_all_vars and copy_all_vars are set to true, then share_all_vars takes precedence.

In addition to the two settings above, it is possible to specify values for variables in the subrequest using the vars option. These variables are set after the sharing or copying of variables has been evaluated, and provides a more efficient method of passing specific values to a subrequest over encoding them as URL arguments and unescaping them in the Nginx config file.

    location /other {
        content_by_lua '
            ngx.say("dog = ", ngx.var.dog)
            ngx.say("cat = ", ngx.var.cat)
        ';
    }
 
    location /lua {
        set $dog '';
        set $cat '';
        content_by_lua '
            res = ngx.location.capture("/other",
                { vars = { dog = "hello", cat = 32 }});
 
            ngx.print(res.body)
        ';
    }

Accessing /lua will yield the output

    dog = hello
    cat = 32

The ctx option can be used to specify a custom Lua table to serve as the ngx.ctx table for the subrequest.

    location /sub {
        content_by_lua '                          
            ngx.ctx.foo = "bar";                  
        ';
    }   
    location /lua {
        content_by_lua '
            local ctx = {}                        
            res = ngx.location.capture("/sub", { ctx = ctx })
 
            ngx.say(ctx.foo);
            ngx.say(ngx.ctx.foo);                 
        ';                                        
    }

Then request GET /lua gives

    bar                                               
    nil

It is also possible to use this ctx option to share the same ngx.ctx table between the current (parent) request and the subrequest:

    location /sub {
        content_by_lua '
            ngx.ctx.foo = "bar";
        ';
    }
    location /lua {
        content_by_lua '
            res = ngx.location.capture("/sub", { ctx = ngx.ctx })
            ngx.say(ngx.ctx.foo);
        ';
    }

Request GET /lua yields the output

    bar

Note that subrequests issued by ngx.location.capture inherit all the request headers of the current request by default and that this may have unexpected side effects on the subrequest responses. For example, when using the standard ngx_proxy module to serve subrequests, an "Accept-Encoding: gzip" header in the main request may result in gzipped responses that cannot be handled properly in Lua code. Original request headers should be ignored by setting proxy_pass_request_headers to off in subrequest locations.

Please also refer to restrictions on capturing locations that include Echo Module directives.

ngx.location.capture_multi

syntax: res1, res2, ... = ngx.location.capture_multi({ {uri, options?}, {uri, options?}, ... })

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Just like ngx.location.capture, but supports multiple subrequests running in parallel.

This function issues several parallel subrequests specified by the input table and returns their results in the same order. For example,

    res1, res2, res3 = ngx.location.capture_multi{
        { "/foo", { args = "a=3&b=4" } },
        { "/bar" },
        { "/baz", { method = ngx.HTTP_POST, body = "hello" } },
    }
 
    if res1.status == ngx.HTTP_OK then
        ...
    end
 
    if res2.body == "BLAH" then
        ...
    end

This function will not return until all the subrequests terminate. The total latency is the longest latency of the individual subrequests rather than the sum.

Lua tables can be used for both requests and responses when the number of subrequests to be issued is not known in advance:

    -- construct the requests table
    local reqs = {}
    table.insert(reqs, { "/mysql" })
    table.insert(reqs, { "/postgres" })
    table.insert(reqs, { "/redis" })
    table.insert(reqs, { "/memcached" })
 
    -- issue all the requests at once and wait until they all return
    local resps = { ngx.location.capture_multi(reqs) }
 
    -- loop over the responses table
    for i, resp in ipairs(resps) do
        -- process the response table "resp"
    end

The ngx.location.capture function is just a special form of this function. Logically speaking, the ngx.location.capture can be implemented like this

    ngx.location.capture =
        function (uri, args)
            return ngx.location.capture_multi({ {uri, args} })
        end

Please also refer to restrictions on capturing locations that include Echo Module directives.

ngx.status

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Read and write the current request's response status. This should be called before sending out the response headers.

    ngx.status = ngx.HTTP_CREATED
    status = ngx.status

ngx.header.HEADER

syntax: ngx.header.HEADER = VALUE

syntax: value = ngx.header.HEADER

context: rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Set, add to, or clear the current request HEADER response header. Underscores (_) in the header names will be replaced by dashes (-) and the header names will be matched case-insensitively.

    -- equivalent to ngx.header["Content-Type"] = 'text/plain'
    ngx.header.content_type = 'text/plain';
 
    ngx.header["X-My-Header"] = 'blah blah';

Multi-value headers can be set this way:

    ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'}

will yield

    Set-Cookie: a=32; path=/
    Set-Cookie: b=4; path=/

in the response headers.

Only Lua tables are accepted (Only the last element in the table will take effect for standard headers such as Content-Type that only accept a single value).

    ngx.header.content_type = {'a', 'b'}

is equivalent to

    ngx.header.content_type = 'b'

Setting a slot to nil effectively removes it from the response headers:

    ngx.header["X-My-Header"] = nil;

The same applies to assigning an empty table:

    ngx.header["X-My-Header"] = {};

Setting ngx.header.HEADER after sending out response headers (either explicitly with ngx.send_headers or implicitly with ngx.print and similar) will throw out a Lua exception.

Reading ngx.header.HEADER will return the value of the response header named HEADER.

Underscores (_) in the header names will also be replaced by dashes (-) and the header names will be matched case-insensitively. If the response header is not present at all, nil will be returned.

This is particularly useful in the context of filter_header_by_lua and filter_header_by_lua_file, for example,

    location /test {
        set $footer '';
 
        proxy_pass http://some-backend;
 
        header_filter_by_lua '
            if ngx.header["X-My-Header"] == "blah" then
                ngx.var.footer = "some value"
            end
        ';
 
        echo_after_body $footer;
    }

For multi-value headers, all of the values of header will be collected in order and returned as a Lua table. For example, response headers

    Foo: bar
    Foo: baz

will result in

    {"bar", "baz"}

to be returned when reading ngx.header.Foo.

Note that ngx.header is not a normal Lua table so you cannot iterate through it using Lua's ipairs function.

For reading request headers, use the ngx.req.get_headers function instead.

ngx.req.set_uri

syntax: ngx.req.set_uri(uri, jump?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Rewrite the current request's (parsed) URI by the uri argument. The uri argument must be a Lua string and cannot be of zero length, or a Lua exception will be thrown.

The optional boolean jump argument can trigger location rematch (or location jump) as HttpRewriteModule's rewrite directive, that is, when jump is true (default to false), this function will never return and it will tell Nginx to try re-searching locations with the new URI value at the later post-rewrite phase and jumping to the new location.

Location jump will not be triggered otherwise, and only the current request's URI will be modified, which is also the default behavior. This function will return but with no returned values when the jump argument is false or absent altogether.

For example, the following nginx config snippet

    rewrite ^ /foo last;

can be coded in Lua like this:

    ngx.req.set_uri("/foo", true)

Similarly, Nginx config

    rewrite ^ /foo break;

can be coded in Lua as

    ngx.req.set_uri("/foo", false)

or equivalently,

    ngx.req.set_uri("/foo")

The jump can only be set to true in rewrite_by_lua and rewrite_by_lua_file. Use of jump in other contexts is prohibited and will throw out a Lua exception.

A more sophisticated example involving regex substitutions is as follows

    location /test {
        rewrite_by_lua '
            local uri = ngx.re.sub(ngx.var.uri, "^/test/(.*)", "$1", "o")
            ngx.req.set_uri(uri)
        ';
        proxy_pass http://my_backend;
    }

which is functionally equivalent to

    location /test {
        rewrite ^/test/(.*) /$1 break;
        proxy_pass http://my_backend;
    }

Note that you cannot use this interface to rewrite URI arguments, and you need to use ngx.req.set_uri_args for that. For instance, Nginx config

    rewrite ^ /foo?a=3? last;

can be coded as

    ngx.req.set_uri_args("a=3")
    ngx.req.set_uri("/foo", true)

or

    ngx.req.set_uri_args({a = 3})
    ngx.req.set_uri("/foo", true)

This interface was first introduced in the v0.3.1rc14 release.

ngx.req.set_uri_args

syntax: ngx.req.set_uri_args(args)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Rewrite the current request's URI query arguments by the args argument. The args argument can be either a Lua string, as in

    ngx.req.set_uri_args("a=3&b=hello%20world")

or a Lua table holding the query arguments' key-value pairs, as in

    ngx.req.set_uri_args({ a = 3, b = "hello world" })

where in the latter case, this method will automatically escape argument keys and values according to the URI escaping rule.

This interface was first introduced in the v0.3.1rc13 release.

See also ngx.req.set_uri.

ngx.req.get_uri_args

syntax: args = ngx.req.get_uri_args()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns a Lua table holds all of the current request's request URL query arguments.

Here is an example,

    location = /test {
        content_by_lua '
            local args = ngx.req.get_uri_args()
            for key, val in pairs(args) do
                if type(val) == "table" then
                    ngx.say(key, ": ", table.concat(val, ", "))
                else
                    ngx.say(key, ": ", val)
                end
            end
        ';
    }

Then GET /test?foo=bar&bar=baz&bar=blah will yield the response body

    foo: bar
    bar: baz, blah

Multiple occurrences of an argument key will result in a table value holding all of the values for that key in order.

Keys and values will be automatically unescaped according to URI escaping rules. For example, in the above settings, GET /test?a%20b=1%61+2 will yield the output

    a b: 1a 2

Arguments without the =<value> parts are treated as boolean arguments. For example, GET /test?foo&bar will yield the outputs

    foo: true
    bar: true

That is, they will take Lua boolean values true. However, they're different from arguments taking empty string values. For example, GET /test?foo=&bar= will give something like

    foo: 
    bar:

Empty key arguments are discarded, for instance, GET /test?=hello&=world will yield empty outputs.

Updating query arguments via the nginx variable $args (or ngx.var.args in Lua) at runtime are also supported:

    ngx.var.args = "a=3&b=42"
    local args = ngx.req.get_uri_args()

Here the args table will always look like

    {a = 3, b = 42}

regardless of the actual request query string.

ngx.req.get_post_args

syntax: ngx.req.get_post_args()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns a Lua table holds all of the current request's POST query arguments (of the MIME type application/x-www-form-urlencoded). It is required to read the request body first by calling ngx.req.read_body or to turn on the lua_need_request_body directive, or a Lua exception will be thrown.

Here is an example,

    location = /test {
        content_by_lua '
            ngx.req.read_body()
            local args = ngx.req.get_post_args()
            for key, val in pairs(args) do
                if type(val) == "table" then
                    ngx.say(key, ": ", table.concat(val, ", "))
                else
                    ngx.say(key, ": ", val)
                end
            end
        ';
    }

Then

    # Post request with the body 'foo=bar&bar=baz&bar=blah'
    $ curl --data 'foo=bar&bar=baz&bar=blah' localhost/test

will yield the response body like

    foo: bar
    bar: baz, blah

Multiple occurrences of an argument key will result in a table value holding all of the values for that key in order.

Keys and values will be automatically unescaped according to URI escaping rules. For example, in the above settings,

    # POST request with body 'a%20b=1%61+2'
    $ curl -d 'a%20b=1%61+2' localhost/test

will yield the output

    a b: 1a 2

Arguments without the =<value> parts are treated as boolean arguments. For example, GET /test?foo&bar will yield the outputs

    foo: true
    bar: true

That is, they will take Lua boolean values true. However, they're different from arguments taking empty string values. For example, POST /test with request body foo=&bar= will give something like

    foo: 
    bar:

Empty key arguments are discarded, for instance, POST /test with body =hello&=world will yield empty outputs.

ngx.req.get_headers

syntax: headers = ngx.req.get_headers()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns a Lua table holds all of the current request's request headers.

Here is an example,

    local h = ngx.req.get_headers()
    for k, v in pairs(h) do
        ...
    end

To read an individual header:

    ngx.say("Host: ", ngx.req.get_headers()["Host"])

For multiple instances of request headers like

    Foo: foo
    Foo: bar
    Foo: baz

the value of ngx.req.get_headers()["Foo"] will be a Lua (array) table like this:

    {"foo", "bar", "baz"}

Another way to read individual request headers is to use ngx.var.http_HEADER, that is, nginx's standard $http_HEADER variables.

ngx.req.set_header

syntax: ngx.req.set_header(header_name, header_value)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Set the current request's request header named header_name to value header_value, overriding any existing ones. None of the current request's subrequests will be affected.

Here is an example of setting the Content-Length header:

    ngx.req.set_header("Content-Type", "text/css")

The header_value can take an array list of values, for example,

    ngx.req.set_header("Foo", {"a", "abc"})

will produce two new request headers:

    Foo: a
    Foo: abc

and old Foo headers will be overridden if there is any.

When the header_value argument is nil, the request header will be removed. So

    ngx.req.set_header("X-Foo", nil)

is equivalent to

    ngx.req.clear_header("X-Foo")

ngx.req.read_body

syntax: ngx.req.read_body()

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Read the client request body synchronously but still non-blockingly.

If the request body is already read previously by turning on lua_need_request_body or by using other modules, then this function is a no-op and returns immediately.

If the request body has already been explicitly discarded, either by this module's ngx.req.discard_body or other modules, this function is a no-op and returns immediately.

In case of errors, like connection errors while reading the data, this method will throw out a Lua exception or terminate the current request with the 500 status code immediately.

You can later either retrieve the request body data via ngx.req.get_body_data or retrieve the temporary file name for the body data cached to disk via ngx.req.get_body_file, depending on

  1. whether the current request body is already exceeding your client_body_buffer_size,
  2. and whether you have turned on client_body_in_file_only.

In case that you do not want to read the request body and the current request may have a request body, then it is crucial to use the ngx.req.discard_body function to explicitly discard the request body, or you'll break HTTP 1.1 keepalive and HTTP 1.1 pipelining.

Here is a small example:

    ngx.req.read_body()
    local args = ngx.req.get_post_args()

This function was first introduced in the v0.3.1rc17 release.

ngx.req.discard_body

syntax: ngx.req.discard_body()

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Explicitly discard the request body, i.e., read the data on the connection and throw it away immediately. Please note that, simply ignoring request body is not the right way to discard it, you need to call this function, or you'll break things under HTTP 1.1 keepalive or HTTP 1.1 pipelining.

This function is an asynchronous call and returns immediately.

If the request body has already been read, this function does nothing and returns immediately.

This function was first introduced in the v0.3.1rc17 release.

See also ngx.req.read_body.

ngx.req.get_body_data

syntax: data = ngx.req.get_body_data()

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Retrieves the in-memory request body data. It returns a Lua string rather than a Lua table holding all the parsed query arguments. If you want the latter, use ngx.req.get_post_args instead.

This function returns nil if

  1. the request body has not been read,
  2. the request body has been read into disk temporary files,
  3. or the request body has zero size.

If the request body has not been read yet, call ngx.req.read_body first (or turned on lua_need_request_body to force this module to read the request body automatically, but this is not recommended).

If the request body has been read into disk files, try calling the ngx.req.get_body_file function instead.

In case that you want to enforce in-memory request bodies, try setting client_body_buffer_size to the same size value in client_max_body_size.

Note that calling this function instead of using ngx.var.request_body or ngx.var.echo_request-body is more efficient because it can save one dynamic memory allocation and one data copy.

This function was first introduced in the v0.3.1rc17 release.

See also ngx.req.get_body_file.

ngx.req.get_body_file

syntax: file_name = ngx.req.get_body_file()

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Retrieves the file name for the in-file request body data. Returns nil if the request body has not been read or has been read into memory.

The returned file is read only and is usually cleaned up automatically by Nginx's memory pool. It should not be modified, renamed, or removed by your own Lua code.

If the request body has not been read yet, call ngx.req.read_body first (or turned on lua_need_request_body to force this module to read the request body automatically, but this is not recommended).

If the request body has been read into memory, try calling the ngx.req.get_body_data function instead.

In case that you want to enforce in-file request bodies, try turning on client_body_in_file_only.

This function was first introduced in the v0.3.1rc17 release.

See also ngx.req.get_body_data.

ngx.req.set_body_data

syntax: ngx.req.set_body_data(data)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Set the current request's request body using the in-memory data specified by the data argument.

If the current request's request body has not been read, then it will be properly discarded. When the current request's request body has been read into memory or buffered into a disk file, then the old request body's memory will be freed or the disk file will be cleaned up immediately, respectively.

This function requires patching the Nginx core to function properly because the Nginx core does not allow modifying request bodies by the current design. Here is a patch for Nginx 1.0.9: nginx-1.0.9-allow_request_body_updating.patch, and this patch should be applied cleanly to other releases of Nginx as well.

This patch has already been applied to ngx_openresty 1.0.8.17 and above.

This function was first introduced in the v0.3.1rc18 release.

See also ngx.req.set_body_file.

ngx.req.set_body_file

syntax: ngx.req.set_body_file(file_name, auto_clean?)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Set the current request's request body using the in-file data specified by the file_name argument.

If the optional auto_clean argument is given a true value, then this file will be automatically removed at request completion or the next time this function or ngx.req.set_body_data are called in the same request. The auto_clean is default to false.

You must ensure that the file specified by the file_name argument exists and is readable by an Nginx worker process by setting its permission properly. Otherwise a Lua exception will be thrown.

If the current request's request body has not been read, then it will be properly discarded. When the current request's request body has been read into memory or buffered into a disk file, then the old request body's memory will be freed or the disk file will be cleaned up immediately, respectively.

This function requires patching the Nginx core to function properly because the Nginx core does not allow modifying request bodies by the current design. Here is a patch for Nginx 1.0.9: nginx-1.0.9-allow_request_body_updating.patch, and this patch should be applied cleanly to other releases of Nginx as well.

If you're using ngx_openresty 1.0.8.17+, then you've already had this patch applied.

This function was first introduced in the v0.3.1rc18 release.

See also ngx.req.set_body_data.

ngx.req.clear_header

syntax: ngx.req.clear_header(header_name)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Clear the current request's request header named header_name. None of the current request's subrequests will be affected.

ngx.exec

syntax: ngx.exec(uri, args?)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Does an internal redirect to uri with args.

    ngx.exec('/some-location');
    ngx.exec('/some-location', 'a=3&b=5&c=6');
    ngx.exec('/some-location?a=3&b=5', 'c=6');

Named locations are also supported, but query strings are ignored. For example,

    location /foo {
        content_by_lua '
            ngx.exec("@bar");
        ';
    }
 
    location @bar {
        ...
    }

The optional second args can be used to specify extra URI query arguments, for example:

    ngx.exec("/foo", "a=3&b=hello%20world")

Alternatively, you can pass a Lua table for the args argument and let ngx_lua do URI escaping and string concatenation automatically for you, for instance,

    ngx.exec("/foo", { a = 3, b = "hello world" })

The result is exactly the same as the previous example. The format for the Lua table passed as the args argument is identical to the format used in the ngx.encode_args method.

Note that this is very different from ngx.redirect in that it is just an internal redirect and no new HTTP traffic is involved.

This method never returns.

This method must be called before ngx.send_headers or explicit response body outputs by either ngx.print or ngx.say.

This method is similar to the echo_exec directive of the HttpEchoModule.

ngx.redirect

syntax: ngx.redirect(uri, status?)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Issue an HTTP 301<code> or <code>302 redirection to uri.

The optional status parameter specifies whether 301 or 302 to be used. It is 302 (ngx.HTTP_MOVED_TEMPORARILY) by default.

Here is an example assuming the current server name is localhost and that it is listening on Port 1984:

    return ngx.redirect("/foo")

which is equivalent to

    return ngx.redirect("http://localhost:1984/foo", ngx.HTTP_MOVED_TEMPORARILY)

We can also use the numberical code directly as the second status argument:

    return ngx.redirect("/foo", 301)

This method must be called before ngx.send_headers or explicit response body outputs by either ngx.print or ngx.say.

This method never returns.

This method is very much like the rewrite directive with the redirect modifier in the standard HttpRewriteModule, for example, this nginx.conf snippet

    rewrite ^ /foo? redirect;  # nginx config

is equivalent to the following Lua code

    return ngx.redirect('/foo');  -- lua code

while

    rewrite ^ /foo? permanent;  # nginx config

is equivalent to

    return ngx.redirect('/foo', ngx.HTTP_MOVED_PERMANENTLY)  -- Lua code

URI arguments can be specified as well, for example:

    return ngx.redirect('/foo?a=3&b=4')

ngx.send_headers

syntax: ngx.send_headers()

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Explicitly send out the response headers.

Usually you do not have to send headers yourself. ngx_lua will automatically send out headers right before you output contents via ngx.say or ngx.print.

Headers will also be sent automatically when content_by_lua exits normally.

ngx.headers_sent

syntax: value = ngx.headers_sent

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns true if the response headers have been sent (by ngx_lua), and false otherwise.

This API was first introduced in ngx_lua v0.3.1rc6.

ngx.print

syntax: ngx.print(...)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Emit arguments concatenated to the HTTP client (as response body). If response headers have not been sent, this function will send headers out first and then output body data.

Lua nil values will output string "nil" and Lua boolean values will output literal strings "true" and "false" respectively.

Nested arrays of strings are permitted and the elements in the arrays will be sent one by one:

    local table = {
        "hello, ",
        {"world: ", true, " or ", false,
            {": ", nil}}
    }
    ngx.print(table)

will yield the output

    hello, world: true or false: nil

Non-array table arguments will cause a Lua exception to be thrown.

This is an asynchronous call and will return immediately without waiting for all the data to be written into the system send buffer. To run in synchronous mode, call ngx.flush(true) after calling ngx.print. This can be particularly useful for streaming output. See ngx.flush for more details.

ngx.say

syntax: ngx.say(...)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Just as ngx.print but also emit a trailing newline.

ngx.log

syntax: ngx.log(log_level, ...)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Log arguments concatenated to error.log with the given logging level.

Lua nil arguments are accepted and result in literal "nil", and Lua booleans result in literal "true" or "false" outputs.

The log_level argument can take constants like ngx.ERR and ngx.WARN. Check out Nginx log level constants for details.

ngx.flush

syntax: ngx.flush(wait?)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Flushes response output to the client.

ngx.flush accepts an optional boolean wait argument (Default: false) first introduced in the v0.3.1rc34 release. When called with the default argument, it issues an asynchronous call (Returns immediately without waiting for output data to be written into the system send buffer). Calling the function with the wait argument set to true switches to synchronous mode.

In synchronous mode, the function will not return until all output data has been written into the system send buffer or until the send_timeout setting has expired. Note that using the Lua coroutine mechanism means that this function does not block the Nginx event loop even in the synchronous mode.

When ngx.flush(true) is called immediately after ngx.print or ngx.say, it causes the latter functions to run in synchronous mode. This can be particularly useful for streaming output.

Note that ngx.flush is non functional when in the HTTP 1.0 output buffering mode. See HTTP 1.0 support.

ngx.exit

syntax: ngx.exit(status)

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

When status >= 200 (i.e., ngx.HTTP_OK and above), it will interrupt the execution of the current request and return status code to nginx.

When status == 0 (i.e., ngx.OK), it will only quit the current phase handler (or the content handler if the content_by_lua directive is used) and continue to run later phases (if any) for the current request.

The status argument can be ngx.OK, ngx.ERROR, ngx.HTTP_NOT_FOUND, ngx.HTTP_MOVED_TEMPORARILY, or other HTTP status constants.

To return an error page with custom contents, use code snippets like this:

    ngx.status = ngx.HTTP_GONE
    ngx.say("This is our own content")
    -- to cause quit the whole request rather than the current phase handler
    ngx.exit(ngx.HTTP_OK)

The effect in action:

    $ curl -i http://localhost/test
    HTTP/1.1 410 Gone
    Server: nginx/1.0.6
    Date: Thu, 15 Sep 2011 00:51:48 GMT
    Content-Type: text/plain
    Transfer-Encoding: chunked
    Connection: keep-alive
 
    This is our own content

Number literals can be used directly as the argument, for instance,

    ngx.exit(501)

ngx.eof

syntax: ngx.eof()

context: rewrite_by_lua*, access_by_lua*, content_by_lua*

Explicitly specify the end of the response output stream.

ngx.escape_uri

syntax: newstr = ngx.escape_uri(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Escape str as a URI component.

ngx.unescape_uri

syntax: newstr = ngx.unescape_uri(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Unescape str as an escaped URI component.

For example,

    ngx.say(ngx.unescape_uri("b%20r56+7"))

gives the output

    b r56 7

ngx.encode_args

syntax: str = ngx.encode_args(table)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Encode the Lua table to a query args string according to the URI encoded rules.

For example,

    ngx.encode_args({foo = 3, ["b r"] = "hello world"})

yields

    foo=3&b%20r=hello%20world

The table keys must be Lua strings.

Multi-value query args are also supported. Just use a Lua table for the arg's value, for example:

    ngx.encode_args({baz = {32, "hello"}})

gives

    baz=32&baz=hello

If the value table is empty and the effect is equivalent to the nil value.

Boolean argument values are also supported, for instance,

    ngx.encode_args({a = true, b = 1})

yields

    a&b=1

If the argument value is false, then the effect is equivalent to the nil value.

This method was first introduced in the v0.3.1rc27 release.

ngx.encode_base64

syntax: newstr = ngx.encode_base64(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Encode str to a base64 digest.

ngx.decode_base64

syntax: newstr = ngx.decode_base64(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Decodes the str argument as a base64 digest to the raw form. Returns nil if str is not well formed.

ngx.crc32_short

syntax: intval = ngx.crc32_short(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Calculates the CRC-32 (Cyclic Redundancy Code) digest for the str argument.

This method performs better on relatively short str inputs (i.e., less than 30 ~ 60 bytes), as compared to ngx.crc32_long. The result is exactly the same as ngx.crc32_long.

Behind the scene, it is just a thin wrapper around the ngx_crc32_short function defined in the Nginx core.

This API was first introduced in the v0.3.1rc8 release.

ngx.crc32_long

syntax: intval = ngx.crc32_long(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Calculates the CRC-32 (Cyclic Redundancy Code) digest for the str argument.

This method performs better on relatively long str inputs (i.e., longer than 30 ~ 60 bytes), as compared to ngx.crc32_short. The result is exactly the same as ngx.crc32_short.

Behind the scene, it is just a thin wrapper around the ngx_crc32_long function defined in the Nginx core.

This API was first introduced in the v0.3.1rc8 release.

ngx.hmac_sha1

syntax: digest = ngx.hmac_sha1(secret_key, str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Computes the HMAC-SHA1 digest of the argument str and turns the result using the secret key <secret_key>.

The raw binary form of the HMAC-SHA1 digest will be generated, use ngx.encode_base64, for example, to encode the result to a textual representation if desired.

For example,

    local key = "thisisverysecretstuff"
    local src = "some string we want to sign"
    local digest = ngx.hmac_sha1(key, src)
    ngx.say(ngx.encode_base64(digest))

yields the output

    R/pvxzHC4NLtj7S+kXFg/NePTmk=

This API requires the OpenSSL library enabled in your Nignx build (usually by passing the --with-http_ssl_module option to the ./configure script).

This function was first introduced in the v0.3.1rc29 release.

ngx.md5

syntax: digest = ngx.md5(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns the hexadecimal representation of the MD5 digest of the str argument.

For example,

    location = /md5 {
        content_by_lua 'ngx.say(ngx.md5("hello"))';
    }

yields the output

    5d41402abc4b2a76b9719d911017c592

See also ngx.md5_bin if you want the raw binary MD5 digest.

ngx.md5_bin

syntax: digest = ngx.md5_bin(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns the binary form of the MD5 digest of the str argument.

See also ngx.md5 if you want the hexadecimal form of the MD5 digest.

ngx.today

syntax: str = ngx.today()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns current date (in the format yyyy-mm-dd) from the nginx cached time (no syscall involved unlike Lua's date library).

This is the local time.

ngx.time

syntax: secs = ngx.time()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns the elapsed seconds from the epoch for the current timestamp from the nginx cached time (no syscall involved unlike Lua's date library).

You can enforce updating the Nginx time cache by calling ngx.update_time first.

ngx.now

syntax: secs = ngx.now()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns a floating-point number for the elapsed time in seconds (including microseconds as the decimal part) from the epoch for the current timestamp from the nginx cached time (no syscall involved unlike Lua's date library).

You can use the standard Nginx directive timer_resolution to adjust the accuracy or forcibly updating the Nginx time cache by calling ngx.update_time first.

This API was first introduced in v0.3.1rc32.

ngx.update_time

syntax: ngx.update_time()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Forcibly updating the Nginx current time cache. This call involves a syscall and thus has some overhead, so do not abuse it.

This API was first introduced in v0.3.1rc32.

ngx.localtime

syntax: str = ngx.localtime()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns the current timestamp (in the format yyyy-mm-dd hh:mm:ss) of the nginx cached time (no syscall involved unlike Lua's os.date function).

This is the local time.

ngx.utctime

syntax: str = ngx.utctime()

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns the current timestamp (in the format yyyy-mm-dd hh:mm:ss) of the nginx cached time (no syscall involved unlike Lua's os.date function).

This is the UTC time.

ngx.cookie_time

syntax: str = ngx.cookie_time(sec)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns a formated string can be used as the cookie expiration time. The parameter sec is the timestamp in seconds (like those returned from ngx.time).

    ngx.say(ngx.cookie_time(1290079655))
        -- yields "Thu, 18-Nov-10 11:27:35 GMT"

ngx.http_time

syntax: str = ngx.http_time(sec)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns a formated string can be used as the http header time (for example, being used in Last-Modified header). The parameter sec is the timestamp in seconds (like those returned from ngx.time).

    ngx.say(ngx.http_time(1290079655))
        -- yields "Thu, 18 Nov 10 11:27:35 GMT"

ngx.parse_http_time

syntax: sec = ngx.parse_http_time(str)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Parse the http time string (as returned by ngx.http_time) into seconds. Returns the seconds or nil if the input string is in bad forms.

    local time = ngx.parse_http_time("Thu, 18 Nov 10 11:27:35 GMT")
    if time == nil then
        ...
    end

ngx.is_subrequest

syntax: value = ngx.is_subrequest

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Returns true if the current request is an nginx subrequest, or false otherwise.

ngx.re.match

syntax: captures = ngx.re.match(subject, regex, options?, ctx?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Matches the subject string using the Perl-compatible regular expression regex with the optional options.

Only the first occurrence of the match is returned, or nil if no match is found. In case of fatal errors, like seeing bad UTF-8 sequences in UTF-8 mode, a Lua exception will be raised.

When a match is found, a Lua table captures is returned, where captures[0] holds the whole substring being matched, and captures[1] holds the first parenthesized subpattern's capturing, captures[2] the second, and so on.

    local m = ngx.re.match("hello, 1234", "[0-9]+")
    -- m[0] == "1234"
    local m = ngx.re.match("hello, 1234", "([0-9])[0-9]+")
    -- m[0] == "1234"
    -- m[1] == "1"

Unmatched subpatterns will have nil values in their captures table fields.

    local m = ngx.re.match("hello, world", "(world)|(hello)")
    -- m[0] == "hello"
    -- m[1] == nil
    -- m[2] == "hello"

You can also specify options to control how the match will be performed. The following option characters are supported:

    a             anchored mode (only match from the beginning)
 
    d             enable the DFA mode (or the longest token match semantics).
                  this requires PCRE 6.0+ or else a Lua exception will be thrown.
                  first introduced in ngx_lua v0.3.1rc30.
 
    i             caseless mode (similar to Perl's /i modifier)
 
    j             enable PCRE JIT compilation, this requires PCRE 8.20+ and
                  PCRE must be built with the --enable-jit option, or it is
                  a no-op. this should always be used along with the <code>o</code> 
                  option to gain the full performance benefit.
                  first introduced in ngx_lua v0.3.1rc30.
 
    m             multi-line mode (similar to Perl's /m modifier)
 
    o             compile-once mode (similar to Perl's /o modifer),
                  to enable the worker-process-level compiled-regex cache
 
    s             single-line mode (similar to Perl's /s modifier)
 
    u             UTF-8 mode. this requires PCRE to be built with
                  the --enable-utf8 option or else a Lua exception will be thrown.
 
    x             extended mode (similar to Perl's /x modifier)

These options can be combined:

    local m = ngx.re.match("hello, world", "HEL LO", "ix")
    -- m[0] == "hello"
    local m = ngx.re.match("hello, 美好生活", "HELLO, (.{2})", "iu")
    -- m[0] == "hello, 美好"
    -- m[1] == "美好"

The o option is useful for performance tuning, because the regex pattern in question will only be compiled once, cached in the worker-process level, and shared among all requests in the current Nginx worker process. You can tune the upper limit of the regex cache via the lua_regex_cache_max_entries directive.

The optional fourth argument, ctx, can be a Lua table holding an optional pos field. When the pos field in the ctx table argument is specified, ngx.re.match will start matching from that offset. Regardless of the presence of the pos field in the ctx table, ngx.re.match will always set this pos field to the position after the substring matched by the whole pattern in case of a successful match. When match fails, the ctx table will be left intact.

    local ctx = {}
    local m = ngx.re.match("1234, hello", "[0-9]+", "", ctx)
         -- m[0] = "1234"
         -- ctx.pos == 4
    local ctx = { pos = 2 }
    local m = ngx.re.match("1234, hello", "[0-9]+", "", ctx)
         -- m[0] = "34"
         -- ctx.pos == 4

The ctx table argument combined with the a regex modifier can be used to construct a lexer atop ngx.re.match.

Note that, the options argument is not optional when the ctx argument is specified; use the empty Lua string ("") as the placeholder for options if you do not want to specify any regex options.

This method requires the PCRE library enabled in your Nginx build. (Known Issue With Special PCRE Sequences).

This feature was introduced in the v0.2.1rc11 release.

ngx.re.gmatch

syntax: iterator = ngx.re.gmatch(subject, regex, options?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Similar to ngx.re.match, but returns a Lua iterator instead, so as to let the user programmer iterate all the matches over the <subject> string argument with the PCRE regex.

Here is a small exmple to demonstrate its basic usage:

    local iterator = ngx.re.gmatch("hello, world!", "([a-z]+)", "i")
    local m
    m = iterator()    -- m[0] == m[1] == "hello"
    m = iterator()    -- m[0] == m[1] == "world"
    m = iterator()    -- m == nil

More often we just put it into a Lua for loop:

    for m in ngx.re.gmatch("hello, world!", "([a-z]+)", "i")
        ngx.say(m[0])
        ngx.say(m[1])
    end

The optional options argument takes exactly the same semantics as the ngx.re.match method.

The current implementation requires that the iterator returned should only be used in a single request. That is, one should not assign it to a variable belonging to persistent namespace like a Lua package.

This method requires the PCRE library enabled in your Nginx build. (Known Issue With Special PCRE Sequences).

This feature was first introduced in the v0.2.1rc12 release.

ngx.re.sub

syntax: newstr, n = ngx.re.sub(subject, regex, replace, options?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Substitutes the first match of the Perl-compatible regular expression regex on the subject argument string with the string or function argument replace. The optional options argument has exactly the same meaning as in ngx.re.match.

This method returns the resulting new string as well as the number of successful substitutions, or throw out a Lua exception when an error occurred (syntax errors in the <replace> string argument, for example).

When the replace is a string, then it is treated as a special template for string replacement. For example,

    local newstr, n = ngx.re.sub("hello, 1234", "([0-9])[0-9]", "[$0][$1]")
        -- newstr == "hello, [12][1]34"
        -- n == 1

where $0 referring to the whole substring matched by the pattern and $1 referring to the first parenthesized capturing substring.

You can also use curly braces to disambiguate variable names from the background string literals:

    local newstr, n = ngx.re.sub("hello, 1234", "[0-9]", "${0}00")
        -- newstr == "hello, 10034"
        -- n == 1

Literal dollar sign characters ($) in the replace string argument can be escaped by another dollar sign, for instance,

    local newstr, n = ngx.re.sub("hello, 1234", "[0-9]", "$$")
        -- newstr == "hello, $234"
        -- n == 1

Do not use backlashes to escape dollar signs; it will not work as expected.

When the replace argument is of type "function", then it will be invoked with the "match table" as the argument to generate the replace string literal for substitution. The "match table" fed into the replace function is exactly the same as the return value of ngx.re.match. Here is an example:

    local func = function (m)
        return "[" .. m[0] .. "][" .. m[1] .. "]"
    end
    local newstr, n = ngx.re.sub("hello, 1234", "( [0-9] ) [0-9]", func, "x")
        -- newstr == "hello, [12][1]34"
        -- n == 1

The dollar sign characters in the return value of the replace function argument are not special at all.

This method requires the PCRE library enabled in your Nginx build. (Known Issue With Special PCRE Sequences).

This feature was first introduced in the v0.2.1rc13 release.

ngx.re.gsub

syntax: newstr, n = ngx.re.gsub(subject, regex, replace, options?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Just like ngx.re.sub, but does global substitution.

Here is some examples:

    local newstr, n = ngx.re.gsub("hello, world", "([a-z])[a-z]+", "[$0,$1]", "i")
        -- newstr == "[hello,h], [world,w]"
        -- n == 2
    local func = function (m)
        return "[" .. m[0] .. "," .. m[1] .. "]"
    end
    local newstr, n = ngx.re.gsub("hello, world", "([a-z])[a-z]+", func, "i")
        -- newstr == "[hello,h], [world,w]"
        -- n == 2

This method requires the PCRE library enabled in your Nginx build. (Known Issue With Special PCRE Sequences).

This feature was first introduced in the v0.2.1rc15 release.

ngx.shared.DICT

syntax: dict = ngx.shared.DICT

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Fetching the shm-based Lua dictionary object for the shared memory zone named DICT defined by the lua_shared_dict directive.

The resulting object dict has the following methods:

Here is an example:

    http {
        lua_shared_dict dogs 10m;
        server {
            location /set {
                content_by_lua '
                    local dogs = ngx.shared.dogs
                    dogs:set("Jim", 8)
                    ngx.say("STORED")
                ';
            }
            location /get {
                content_by_lua '
                    local dogs = ngx.shared.dogs
                    ngx.say(dogs:get("Jim"))
                ';
            }
        }
    }

Let us test it:

    $ curl localhost/set
    STORED
 
    $ curl localhost/get
    8
 
    $ curl localhost/get
    8

You will consistently get the output 8 when accessing /get regardless how many Nginx workers there are because the dogs dictionary resides in the shared memory and visible to all of the worker processes.

The shared dictionary will retain its contents through a server config reload (either by sending the HUP signal to the Nginx process or by using the -s reload command-line option).

The contents in the dictionary storage will be lost, however, when the Nginx server quits.

This feature was first introduced in the v0.3.1rc22 release.

ngx.shared.DICT.get

syntax: value = ngx.shared.DICT:get(key)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Retrieving the value in the dictionary ngx.shared.DICT for the key key. If the key does not exist or has been expired, then nil will be returned.

The value returned will have the original data type when they were inserted into the dictionary, for example, Lua booleans, numbers, or strings.

The first argument to this method must be the dictionary object itself, for example,

    local cats = ngx.shared.cats
    local value = cats.get(cats, "Marry")

or use Lua's syntactic sugar for method calls:

    local cats = ngx.shared.cats
    local value = cats:get("Marry")

These two forms are fundamentally equivalent.

This feature was first introduced in the v0.3.1rc22 release.

See also ngx.shared.DICT.

ngx.shared.DICT.set

syntax: success, err, forcible = ngx.shared.DICT:set(key, value, exptime?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Unconditionally sets a key-value pair into the shm-based dictionary ngx.shared.DICT. Returns three values:

  • success: boolean value to indicate whether the key-value pair is stored or not.
  • err: textual error message, can be "no memory".
  • forcible: a boolean value to indicate whether other valid items have been removed forcibly when out of storage in the shared memory zone.

The value argument inserted can be Lua booleans, numbers, strings, or nil. Their value type will also be stored into the dictionary, thus you can get exactly the same data type when later retrieving the value out of the dictionary via the get method.

The optional exptime argument specifies expiration time (in seconds) for the inserted key-value pair. The time resolution is 0.001 seconds. If the exptime takes the value 0 (which is the default), then the item will never be expired.

When it fails to allocate memory for the current key-value item, then set will try removing existing items in the storage according to the Least-Recently Used (LRU) algorithm. Note that, LRU takes priority over expiration time here. If up to tens of existing items have been removed and the storage left is still insufficient (either due to the total capacity limit specified by lua_shared_dict or memory segmentation), then the err return value will be no memory and success will be false.

If this method succeeds in storing the current item by forcibly removing other not-yet-expired items in the dictionary via LRU, the forcible return value will be true. If it stores the item without forcibly removing other valid items, then the return value forcible will be false.

The first argument to this method must be the dictionary object itself, for example,

    local cats = ngx.shared.cats
    local succ, err, forcible = cats.set(cats, "Marry", "it is a nice cat!")

or use Lua's syntactic sugar for method calls:

    local cats = ngx.shared.cats
    local succ, err, forcible = cats:set("Marry", "it is a nice cat!")

These two forms are fundamentally equivalent.

This feature was first introduced in the v0.3.1rc22 release.

See also ngx.shared.DICT.

ngx.shared.DICT.add

syntax: success, err, forcible = ngx.shared.DICT:add(key, value, exptime?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Just like the set method, but only stores the key-value pair into the dictionary ngx.shared.DICT if the key does not exist.

If the key argument already exists in the dictionary (and not expired for sure), the success return value will be false and the err return value will be "exists".

This feature was first introduced in the v0.3.1rc22 release.

See also ngx.shared.DICT.

ngx.shared.DICT.replace

syntax: success, err, forcible = ngx.shared.DICT:replace(key, value, exptime?)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Just like the set method, but only stores the key-value pair into the dictionary ngx.shared.DICT if the key does exist.

If the key argument does not exist in the dictionary (or expired already), the success return value will be false and the err return value will be "not found".

This feature was first introduced in the v0.3.1rc22 release.

See also ngx.shared.DICT.

ngx.shared.DICT.delete

syntax: ngx.shared.DICT:delete(key)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Unconditionally removes the key-value pair from the shm-based dictionary ngx.shared.DICT.

It is equivalent to ngx.shared.DICT:set(key, nil).

This feature was first introduced in the v0.3.1rc22 release.

See also ngx.shared.DICT.

ngx.shared.DICT.incr

syntax: newval, err = ngx.shared.DICT:incr(key, value)

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

Increments the (numerical) value for key in the shm-based dictionary ngx.shared.DICT by the step value value. Returns the new resulting number if the operation is successfully completed or nil and an error message otherwise.

The key must already exist in the dictionary, otherwise it will return nil and "not found".

If the original value is not a valid Lua number in the dictionary, it will return nil and "not a number".

The value argument can be any valid Lua numbers, like negative numbers or floating-point numbers.

This feature was first introduced in the v0.3.1rc22 release.

See also ngx.shared.DICT.

ndk.set_var.DIRECTIVE

syntax: res = ndk.set_var.DIRECTIVE_NAME

context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*

This mechanism allows calling other nginx C modules' directives that are implemented by Nginx Devel Kit (NDK)'s set_var submodule's ndk_set_var_value.

For example, the following HttpSetMiscModule directives can be invoked this way:

For instance,

    local res = ndk.set_var.set_escape_uri('a/b');
    -- now res == 'a%2fb'

Similarly, the following directives provided by HttpEncryptedSessionModule can be invoked from within Lua too:

This feature requires the ngx_devel_kit module.

HTTP 1.0 support

The HTTP 1.0 protocol does not support chunked outputs and always requires an explicit Content-Length header when the response body is non-empty. So when an HTTP 1.0 request is present, This module will automatically buffer all the outputs of user calls of ngx.say and ngx.print and postpone sending response headers until it sees all the outputs in the response body, and at that time ngx_lua can calculate the total length of the body and construct a proper Content-Length header for the HTTP 1.0 client.

Note that, common HTTP benchmark tools like ab and http_load always issue HTTP 1.0 requests by default. To force curl to send HTTP 1.0 requests, use the -0 option.

Data Sharing within an Nginx Worker

NOTE: This mechanism behaves differently when code cache is turned off, and should be considered as a DIRTY TRICK. Backward compatibility is NOT guaranteed. Use at your own risk! We're going to design a whole new data-sharing mechanism.

If you want to globally share user data among all the requests handled by the same nginx worker process, you can encapsulate your shared data into a Lua module, require the module in your code, and manipulate shared data through it. It works because required Lua modules are loaded only once, and all coroutines will share the same copy of the module. Note however that Lua global variables WILL NOT persist between requests because of the one-coroutine-per-request isolation design.

Here is a complete small example:

    -- mydata.lua
    module("mydata", package.seeall)
 
    local data = {
        dog = 3,
        cat = 4,
        pig = 5,
    }
 
    function get_age(name)
        return data[name]
    end

and then accessing it from your nginx.conf:

    location /lua {
        content_lua_by_lua '
            local mydata = require("mydata")
            ngx.say(mydata.get_age("dog"))
        ';
    }

Your mydata module in this example will only be loaded and run on the first request to the location /lua, and all those subsequent requests to the same nginx worker process will use the reloaded instance of the module as well as the same copy of the data in it, until you send a HUP signal to the nginx master process to enforce a reload.

This data sharing technique is essential for high-performance Lua apps built atop this module. It is common to cache reusable data globally.

It is worth noting that this is per-worker sharing, not per-server sharing. That is, when you have multiple nginx worker processes under an nginx master, this data sharing cannot pass process boundary. If you indeed need server-wide data sharing, you can

  1. Use only a single nginx worker and a single server. This is not recommended when you have a multi-core CPU or multiple CPUs in a single machine.
  2. Use some true backend storage like memcached, redis, or an RDBMS like mysql.

Known Issues

Lua Coroutine Yielding/Resuming

  • As the module's predefined Nginx I/O API uses the coroutine yielding/resuming mechanism, user code should not call any Lua modules that use the Lua coroutine mechanism in order to prevent conflicts with the module's predefined Nginx API methods such as ngx.location.capture (Actually, coroutine modules have been masked off in content_by_lua directives and others). This limitation is significant and work is ongoing on an alternative coroutine implementation that can fit into the Nginx event model to address this. When this is done, it will be possible to use the Lua coroutine mechanism freely as it is in standard Lua implementations.
  • Lua's dofile builtin is implemented as a C function in both Lua 5.1 and LuaJIT 2.0 and when you call ngx.location.capture, ngx.exec, ngx.exit or ngx.req.read_body or similar in the file to be loaded by dofile, a coroutine yield across the C function boundary will be initiated. This however is not allowed within ngx_lua and will usually result in error messages like lua handler aborted: runtime error: attempt to yield across C-call boundary. To avoid this, define a real Lua module in your .lua file and use Lua's require builtin instead.
  • Because the standard Lua 5.1 interpreter's VM is not fully resumable, the methods ngx.location.capture, ngx.location.capture_multi, ngx.redirect, ngx.exec, and ngx.exit cannot be used within the context of a Lua pcall() or xpcall() when the standard Lua 5.1 interpreter is used; you'll get the error attempt to yield across metamethod/C-call boundary. To fix this, please use LuaJIT 2.0 instead, because LuaJIT 2.0 supports a fully resume-able VM.

Lua Variable Scope

Care should be taken when importing modules and this form should be used:

        local xxx = require('xxx')
instead of the old deprecated form:
        require('xxx')
If you have to use the old form, force reload the module for every request by using the package.loaded.<module> command:
        package.loaded.xxx = nil
        require('xxx')

It is recommended to always place the following piece of code at the end of Lua modules that use the ngx.location.capture or ngx.location.capture_multi directives to prevent casual use of module-level global variables that are shared among all requests:

    getmetatable(foo.bar).__newindex = function (table, key, val)
        error('Attempt to write to undeclared variable "' .. key .. '": '
                .. debug.traceback())
    end

Assuming your current Lua module is named foo.bar, this will guarantee that local variables in module foo.bar functions have been declared as "local". It prevents undesirable race conditions while accessing such variables. See Data Sharing within an Nginx Worker for the reasons behind this.

Locations With HttpEchoModule Directives

The ngx.location.capture and ngx.location.capture_multi directives cannot capture locations that include the echo_location, echo_location_async, echo_subrequest, or echo_subrequest_async directives.

    location /foo {
        content_by_lua '
            res = ngx.location.capature("/bar")
        ';
    }
    location /bar {
        echo_location /blah;
    }
    location /blah {
        echo "Success!";
    }
    $ curl -i http://example.com/foo

will not work as expected.

Special PCRE Sequences

PCRE sequences such as \d, \s, or \w, require special attention because in string literals, the backslash character, \, is stripped out by both the Lua language parser and by the Nginx config file parser before processing. So the following snippet will not work as expected:

    # nginx.conf
    ? location /test {
    ?     content_by_lua '
    ?         local regex = "\d+"  -- THIS IS WRONG!!
    ?         local m = ngx.re.match("hello, 1234", regex)
    ?         if m then ngx.say(m[0]) else ngx.say("not matched!") end
    ?     ';
    ? }
    # evaluates to "not matched!"

To avoid this, you need to double escape the backslash:

    # nginx.conf
    location /test {
        content_by_lua '
            local regex = "\\\\d+"
            local m = ngx.re.match("hello, 1234", regex)
            if m then ngx.say(m[0]) else ngx.say("not matched!") end
        ';
    }
    # evaluates to "1234"

Here, \\\\d+ is stripped down to \\d+ by the Nginx config file parser and this is further stripped down to \d+ by the Lua language parser before running.

Alternatively, you can present the regex pattern as a long-bracketed lua string literal by encasing it in "long brackets", [[...]], in which case backslashes have to only be escaped once for the Nginx config file parser.

    # nginx.conf
    location /test {
        content_by_lua '
            local regex = [[\\d+]]
            local m = ngx.re.match("hello, 1234", regex)
            if m then ngx.say(m[0]) else ngx.say("not matched!") end
        ';
    }
    # evaluates to "1234"

Here, [[\\d+]] is stripped down to [[\d+]] by the Nginx config file parser and this is processed correctly.

Note that you may need to use a longer from of the long bracket, [=[...]=], if the regex pattern contains [...] sequences. You can also, if you wish, use the [=[...]=] form as your default form and it may help with readability if you put a space between your long brackets and your regex patterns.

    # nginx.conf
    location /test {
        content_by_lua '
            local regex = [=[ [0-9]+ ]=]
            local m = ngx.re.match("hello, 1234", regex)
            if m then ngx.say(m[0]) else ngx.say("not matched!") end
        ';
    }
    # evaluates to "1234"

An alternative approach to escaping PCRE sequences is to ensure that Lua code is placed in external script files and executed using the various *_by_lua_file directives. With this approach, the backslashes are only stripped by the Lua language parser and therefore only need to be escaped once each.

    -- test.lua
    local regex = "\\d+"
    local m = ngx.re.match("hello, 1234", regex)
    if m then ngx.say(m[0]) else ngx.say("not matched!") end
    -- evaluates to "1234"

Within external script files, PCRE sequences presented as long-bracketed lua string literals do not require modification.

    -- test.lua
    local regex = [[\d+]]
    local m = ngx.re.match("hello, 1234", regex)
    if m then ngx.say(m[0]) else ngx.say("not matched!") end
    -- evaluates to "1234"

Typical Uses

Just to name a few:

  • Mashup'ing and processing outputs of various nginx upstream outputs (proxy, drizzle, postgres, redis, memcached, and etc) in Lua,
  • doing arbitrarily complex access control and security checks in Lua before requests actually reach the upstream backends,
  • manipulating response headers in an arbitrary way (by Lua)
  • fetching backend information from external storage backends (like redis, memcached, mysql, postgresql) and use that information to choose which upstream backend to access on-the-fly,
  • coding up arbitrarily complex web applications in a content handler using synchronous but still non-blocking access to the database backends and other storage,
  • doing very complex URL dispatch in Lua at rewrite phase,
  • using Lua to implement advanced caching mechanism for nginx subrequests and arbitrary locations.

The possibilities are unlimited as the module allows bringing together various elements within Nginx as well as exposing the power of the Lua language to the user. The module provides the full flexibility of scripting while offering performance levels comparable with native C language programs both in terms of CPU time as well as memory footprint. This is particularly the case when LuaJIT 2.0 is enabled.

Other scripting language implementations typically struggle to match this performance level.

The Lua state (Lua VM instance) is shared across all the requests handled by a single nginx worker process to miminize memory use.

On a ThinkPad T400 2.80 GHz laptop, the HelloWorld example readily achieves 28k req/sec using http_load -p 10. By contrast, Nginx + php-fpm 5.2.8 + Unix Domain Socket yields 6k req/sec and Node.js v0.6.1 yields 10.2k req/sec for their HelloWorld equivalents.

This module performs best when built with LuaJIT 2.0.

Nginx Compatibility

The module is compatible with the following versions of Nginx:

  • 1.1.x (last tested: 1.1.5)
  • 1.0.x (last tested: 1.0.10)
  • 0.9.x (last tested: 0.9.4)
  • 0.8.x >= 0.8.54 (last tested: 0.8.54)

Code Repository

The code repository of this project is hosted on github at chaoslawful/lua-nginx-module.

安装

You may wish to consider using the ngx_openresty bundle to install Nginx, ngx_lua, either one of the Standard Lua interpreter or LuaJIT, as well as a package of powerful companion Nginx modules:

http://openresty.org

最简单的安装方式是 ./configure --with-luajit && make && make install.

当然,你也可以选择单独编译 ngx_lua 模块到 Nginx 中:

  1. 安装 Lua 5.1 或者 LuaJIT 2.0 (推荐). Lua 可以从 Lua 主页 免费获取。你的发行版中可能也包括 Lua。
  2. 下载最新的 ngx_devel_kit (NDK) 模块 HERE.
  3. 下载最新的 HERE.
  4. 下载最新的 Nginx HERE (See Nginx Compatibility)

从源码编译模块:

    wget 'http://nginx.org/download/nginx-1.0.10.tar.gz'
    tar -xzvf nginx-1.0.10.tar.gz
    cd nginx-1.0.10/
 
    # 设置 Lua 环境变量
    export LUA_LIB=/path/to/lua/lib
    export LUA_INC=/path/to/lua/include
 
    # 或者设置 LuaJIT 环境变量
    # export LUAJIT_LIB=/path/to/luajit/lib
    # export LUAJIT_INC=/path/to/luajit/include/luajit-2.0
 
    # 这里假设 Nginx 安装路径是 /opt/nginx/
    ./configure --prefix=/opt/nginx \
            --add-module=/path/to/ngx_devel_kit \
            --add-module=/path/to/lua-nginx-module
 
    make -j2
    make install

Bugs and Patches

Please report bugs or submit patches by:

  1. Creating a ticket on the GitHub issue tracker (Recommended)
  2. Posting to the Nginx mailing list.

TODO

Short Term

  • add ignore_resp_headers, ignore_resp_body, and ignore_resp options to ngx.location.capture and ngx.location.capture_multi` methods, to allow micro performance tuning on the user side.
  • add directives to run lua codes when nginx stops/reloads.
  • deal with TCP 3-second delay problem under great connection harness.
  • add options to ngx.location.capture and ngx.location.capture_multi in order to share and copy a particular set of nginx variables with subrequests, specified by the user.
  • add an option to ngx.location.capture and ngx.location.capture_multi so as to specify the ngx.ctx table for subrequests.
  • add support for multi-value arguments to #ngx.req.set_uri_args if its args argument is a Lua table.
  • add APIs to access cookies as key/value pairs.

Longer Term

  • add the lua_require directive to load module into main thread's globals.
  • add the "cosocket" mechamism that will emulate a common set of Lua socket API that will give you totally transparently non-blocking capability out of the box by means of a completely new upstream layer atop the nginx event model and no nginx subrequest overheads.
  • add Lua code automatic time slicing support by yielding and resuming the Lua VM actively via Lua's debug hooks.
  • make set_by_lua using the same mechanism as content_by_lua.
  • add coroutine API back to the Lua land.

Changes

v0.3.0

New features

  • added the header_filter_by_lua and header_filter_by_lua_file directives. thanks Liseen Wan (万珣新).
  • implemented the PCRE regex API for Lua: ngx.re.match, ngx.re.gmatch, ngx.re.sub, and ngx.re.gsub.
  • now we add the ngx and ndk table into package.loaded such that the user can write local ngx = require 'ngx' and local ndk = require 'ndk'. thanks @Lance.
  • added new directive lua_regex_cache_max_entries to control the upper limit of the worker-process-level compiled-regex cache enabled by the o regex option.
  • implemented the special ngx.ctx Lua table for user programmers to store per-request Lua context data for their applications. thanks 欧远宁 for suggesting this feature.
  • now ngx.print and ngx.say allow (nested) array-like table arguments. the array elements in them will be sent piece by piece. this will avoid string concatenation for templating engines like ltp.
  • implemented the ngx.req.get_post_args method for fetching url-encoded POST query arguments from within Lua.
  • implemented the ngx.req.get_uri_args method to fetch parsed URL query arguments from within Lua. thanks Bertrand Mansion (golgote).
  • added new function ngx.parse_http_time, thanks James Hurst.
  • now we allow Lua boolean and nil values in arguments to ngx.say, ngx.print, ngx.log and print.
  • added support for user C macros LUA_DEFAULT_PATH and LUA_DEFAULT_CPATH. for now we can only define them in ngx_lua's config file because nginx configure's --with-cc-opt option hates values with double-quotes in them. sigh. ngx_openresty is already using this feature to bundle 3rd-party Lua libraries.

Bug fixes

  • worked-around the "stack overflow" issue while using luarocks.loader and disabling lua_code_cache, as described as github issue #27. thanks Patrick Crosby.
  • fixed the zero size buf in output alert while combining lua_need_request_body on + access_by_lua/rewrite_by_lua + proxy_pass/fastcgi_pass. thanks Liseen Wan (万珣新).
  • fixed issues with HTTP 1.0 HEAD requests.
  • made setting ngx.header.HEADER after sending out response headers throw out a Lua exception to help debugging issues like github issue #49. thanks Bill Donahue (ikhoyo).
  • fixed an issue regarding defining global variables in C header files: we should have defined the global ngx_http_lua_exception in a single compilation unit. thanks @姜大炮.

测试用例

运行测试用例,有以下依赖:

  • Nginx 版本 >= 0.8.54
  • Applications:
    • mysql: create database 'ngx_test', grant all privileges to user 'ngx_test', password is 'ngx_test'
    • memcached

下面的模块在配置时候顺序很重要,正确的顺序如下:

  1. ngx_devel_kit
  2. set-misc-nginx-module
  3. ngx_http_auth_request_module
  4. echo-nginx-module
  5. memc-nginx-module
  6. lua-nginx-module (i.e. this module)
  7. headers-more-nginx-module
  8. srcache-nginx-module
  9. drizzle-nginx-module
  10. rds-json-nginx-module

Copyright and License

This module is licenced under the BSD license.

Copyright (C) 2009-2011, by Xiaozhe Wang (chaoslawful) <chaoslawful@gmail.com>.

Copyright (C) 2009-2011, by Zhang "agentzh" Yichun (章亦春) <agentzh@gmail.com>.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

其他参考