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(set_rotate)
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= Version =
 
= Version =
  
This document describes set-misc-nginx-module [https://github.com/agentzh/set-misc-nginx-module/tags v0.22rc3] released on 10 October 2011.
+
This document describes set-misc-nginx-module [https://github.com/agentzh/set-misc-nginx-module/tags v0.22rc8] released on 10 May 2012.
  
 
= Synopsis =
 
= Synopsis =
Line 748: Line 748:
  
 
Behind the scene, it makes use of the standard C function <code>rand()</code>.
 
Behind the scene, it makes use of the standard C function <code>rand()</code>.
 +
 +
This directive was first introduced in the <code>v0.22rc1</code> release.
 +
 +
See also [[#set_secure_random_alphanum|set_secure_random_alphanum]] and [[#set_secure_random_lcalpha|set_secure_random_lcalpha]].
 +
 +
== set_secure_random_alphanum ==
 +
'''syntax:''' ''set_secure_random_alphanum $res <length>''
 +
 +
'''default:''' ''no''
 +
 +
'''context:''' ''location, location if''
 +
 +
'''phase:''' ''rewrite''
 +
 +
Generates a cryptographically-strong random string <code><length></code> characters long with the alphabet <code>[a-zA-Z0-9]</code>.
 +
 +
<code><length></code> may be between 1 and 64, inclusive.
 +
 +
For instance,
 +
 +
<geshi lang="nginx">
 +
    location /test {
 +
        set_secure_random_alphanum $res 32;
 +
 +
        echo $res;
 +
    }
 +
</geshi>
 +
 +
then request <code>GET /test</code> will output a string like <code>ivVVRP2DGaAqDmdf3Rv4ZDJ7k0gOfASz</code>.
 +
 +
This function depends on the presence of the <code>/dev/urandom</code> device, available on most UNIX-like systems.
 +
 +
See also [[#set_secure_random_lcalpha|set_secure_random_lcalpha]] and [[#set_random|set_random]].
 +
 +
This directive was first introduced in the <code>v0.22rc8</code> release.
 +
 +
== set_secure_random_lcalpha ==
 +
'''syntax:''' ''set_secure_random_lcalpha $res <length>''
 +
 +
'''default:''' ''no''
 +
 +
'''context:''' ''location, location if''
 +
 +
'''phase:''' ''rewrite''
 +
 +
Generates a cryptographically-strong random string <code><length></code> characters long with the alphabet <code>[a-z]</code>.
 +
 +
<code><length></code> may be between 1 and 64, inclusive.
 +
 +
For instance,
 +
 +
<geshi lang="nginx">
 +
    location /test {
 +
        set_secure_random_lcalpha $res 32;
 +
 +
        echo $res;
 +
    }
 +
</geshi>
 +
 +
then request <code>GET /test</code> will output a string like <code>kcuxcddktffsippuekhshdaclaquiusj</code>.
 +
 +
This function depends on the presence of the <code>/dev/urandom</code> device, available on most UNIX-like systems.
 +
 +
This directive was first introduced in the <code>v0.22rc8</code> release.
 +
 +
See also [[#set_secure_random_alphanum|set_secure_random_alphanum]] and [[#set_random|set_random]].
 +
 +
== set_rotate ==
 +
'''syntax:''' ''set_rotate $value <from> <to>''
 +
 +
'''default:''' ''no''
 +
 +
'''context:''' ''location, location if''
 +
 +
'''phase:''' ''rewrite''
 +
 +
Increments <code>$value</code> but keeps it in range from <code><from></code> to <code><to></code>.
 +
If <code>$value</code> is greater than <code><to></code> or less than <code><from></code> is will be
 +
set to <code><from></code> value.
 +
 +
The current value after running this directive will always be saved on a per-location basis. And the this saved value will be used for incrementation when the <code>$value</code> is not initialized or has a bad value.
 +
 +
Only non-negative numbers are allowed for the <code><from></code> and <code><to></code> arguments.
 +
 +
When <code><from></code> is greater than <code><to></code>, their values will be exchanged accordingly.
 +
 +
For instance,
 +
 +
<geshi lang="nginx">
 +
    location /rotate {
 +
        default_type text/plain;
 +
        set $counter $cookie_counter;
 +
        set_rotate $counter 1 5;
 +
        echo $counter;
 +
        add_header Set-Cookie counter=$counter;
 +
    }
 +
</geshi>
 +
 +
then request <code>GET /rotate</code> will output next number between 1 and 5 (i.e., 1, 2, 3, 4, 5) on each
 +
refresh of the page. This directive may be userful for banner rotation purposes.
 +
 +
Another example is to use server-side value persistence to do simple round-robin:
 +
 +
<geshi lang="nginx">
 +
    location /rotate {
 +
        default_type text/plain;
 +
        set_rotate $counter 0 3;
 +
        echo $counter;
 +
    }
 +
</geshi>
 +
 +
And accessing <code>/rotate</code> will also output integer sequence 0, 1, 2, 3, 0, 1, 2, 3, and so on.
 +
 +
This directive was first introduced in the <code>v0.22rc7</code> release.
  
 
== set_local_today ==
 
== set_local_today ==
Line 792: Line 906:
  
 
Grab the nginx source code from [http://nginx.org/ nginx.org], for example,
 
Grab the nginx source code from [http://nginx.org/ nginx.org], for example,
the version 1.0.8 (see [[#Compatibility|nginx compatibility]]), and then build the source with this module:
+
the version 1.0.15 (see [[#Compatibility|nginx compatibility]]), and then build the source with this module:
  
 
<geshi lang="bash">
 
<geshi lang="bash">
     wget 'http://nginx.org/download/nginx-1.0.8.tar.gz'
+
     wget 'http://nginx.org/download/nginx-1.0.15.tar.gz'
     tar -xzvf nginx-1.0.8.tar.gz
+
     tar -xzvf nginx-1.0.15.tar.gz
     cd nginx-1.0.8/
+
     cd nginx-1.0.15/
 
      
 
      
 
     # Here we assume you would install you nginx under /opt/nginx/.
 
     # Here we assume you would install you nginx under /opt/nginx/.
Line 818: Line 932:
  
 
* '''1.1.x'''                      (last tested: 1.1.5)
 
* '''1.1.x'''                      (last tested: 1.1.5)
* '''1.0.x'''                      (last tested: 1.0.8)
+
* '''1.0.x'''                      (last tested: 1.0.15)
 
* '''0.9.x'''                      (last tested: 0.9.4)
 
* '''0.9.x'''                      (last tested: 0.9.4)
 
* '''0.8.x'''                      (last tested: 0.8.54)
 
* '''0.8.x'''                      (last tested: 0.8.54)

Revision as of 05:41, 10 May 2012

Contents

Name

ngx_set_misc - Various set_xxx directives added to nginx's rewrite module (md5/sha1, sql/json quoting, and many more)

This module is not distributed with the Nginx source. See the installation instructions.

Version

This document describes set-misc-nginx-module v0.22rc8 released on 10 May 2012.

Synopsis

    location /foo {
        set $a $arg_a;
        set_if_empty $a 56;
 
        # GET /foo?a=32 will yield $a == 32
        # while GET /foo and GET /foo?a= will
        # yeild $a == 56 here.
    }
 
    location /bar {
        set $foo "hello\n\n'\"\\";
        set_quote_sql_str $foo $foo; # for mysql
 
        # OR in-place editing:
        #   set_quote_sql_str $foo;
 
        # now $foo is: 'hello\n\n\'\"\\'
    }
 
    location /bar {
        set $foo "hello\n\n'\"\\";
        set_quote_pgsql_str $foo;  # for PostgreSQL
 
        # now $foo is: E'hello\n\n\'\"\\'
    }
 
    location /json {
        set $foo "hello\n\n'\"\\";
        set_quote_json_str $foo $foo;
 
        # OR in-place editing:
        #   set_quote_json_str $foo;
 
        # now $foo is: "hello\n\n'\"\\"
    }
 
    location /baz {
        set $foo "hello%20world";
        set_unescape_uri $foo $foo;
 
        # OR in-place editing:
        #   set_unescape_uri $foo;
 
        # now $foo is: hello world
    }
 
    upstream_list universe moon sun earth;
    upstream moon { ... }
    upstream sun { ... }
    upstream earth { ... }
    location /foo {
        set_hashed_upstream $backend universe $arg_id;
        drizzle_pass $backend; # used with ngx_drizzle
    }
 
    location /base32 {
        set $a 'abcde';
        set_encode_base32 $a;
        set_decode_base32 $b $a;
 
        # now $a == 'c5h66p35' and
        # $b == 'abcde'
    }
 
    location /base64 {
        set $a 'abcde';
        set_encode_base64 $a;
        set_decode_base64 $b $a;
 
        # now $a == 'YWJjZGU=' and
        # $b == 'abcde'
    }
 
    location /hex {
        set $a 'abcde';
        set_encode_hex $a;
        set_decode_hex $b $a;
 
        # now $a == '6162636465' and
        # $b == 'abcde'
    }
 
    # GET /sha1 yields the output
    #   aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d
    location /sha1 {
        set_sha1 $a hello;
        echo $a;
    }
 
    # ditto
    location /sha1 {
        set $a hello;
        set_sha1 $a;
        echo $a;
    }
 
    # GET /today yields the date of today in local time using format 'yyyy-mm-dd'
    location /today {
        set_local_today $today;
        echo $today;
    }
 
    # GET /signature yields the hmac-sha-1 signature
    # given a secret and a string to sign
    # this example yields the base64 encoded singature which is
    # "HkADYytcoQQzqbjQX33k/ZBB/DQ="
    location /signature {
        set $secret_key 'secret-key';
        set $string_to_sign "some-string-to-sign";
        set_hmac_sha1 $signature $secret_key $string_to_sign;
        set_encode_base64 $signature $signature;
        echo $signature;
    }
 
    location = /rand {
        set $from 3;
        set $to 15;
        set_random $rand $from $to;
 
        # or write directly
        #   set_random $rand 3 15;
 
        echo $rand;  # will print a random integer in the range [3, 15]
    }

Description

This module extends the standard HttpRewriteModule's directive set to provide more functionalities like URI escaping and unescaping, JSON quoting, Hexadecimal/MD5/SHA1/Base32/Base64 digest encoding and decoding, random number generator, and more!

Every directive provided by this module can be mixed freely with other HttpRewriteModule's directives, like if and set. (Thanks to the Nginx Devel Kit!)

Directives

set_if_empty

syntax: set_if_empty $dst <src>

default: no

context: location, location if

phase: rewrite

Assign the value of the argument <src> if and only if variable $dst is empty (i.e., not found or has an empty string value).

In the following example,

    set $a 32;
    set_if_empty $a 56;

the variable $dst will take the value 32 at last. But in the sample

    set $a '';
    set $value "hello, world"
    set_if_empty $a $value;

$a will take the value "hello, world" at last.

set_quote_sql_str

syntax: set_quote_sql_str $dst <src>

syntax: set_quote_sql_str $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will quote the value of the second argument <src> by MySQL's string value quoting rule and assign the result into the first argument, variable $dst. For example,

    location /test {
        set $value "hello\n\r'\"\\";
        set_quote_sql_str $quoted $value;
 
        echo $quoted;
    }

Then request GET /test will yield the following output

'hello\n\r\'\"\\'

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "hello\n\r'\"\\";
        set_quote_sql_str $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive is usually used to prevent SQL injection.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_quote_pgsql_str

syntax: set_quote_pgsql_str $dst <src>

syntax: set_quote_pgsql_str $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

Very much like set_quote_sql_str, but with PostgreSQL quoting rules for SQL string literals.

set_quote_json_str

syntax: set_quote_json_str $dst <src>

syntax: set_quote_json_str $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will quote the value of the second argument <src> by JSON string value quoting rule and assign the result into the first argument, variable $dst. For example,

    location /test {
        set $value "hello\n\r'\"\\";
        set_quote_json_str $quoted $value;
 
        echo $quoted;
    }

Then request GET /test will yield the following output

"hello\n\r'\"\\"

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "hello\n\r'\"\\";
        set_quote_json_str $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_unescape_uri

syntax: set_unescape_uri $dst <src>

syntax: set_unescape_uri $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will unescape the value of the second argument <src> as a URI component and assign the result into the first argument, variable $dst. For example,

    location /test {
        set_unescape_uri $key $arg_key;
        echo $key;
    }

Then request GET /test?key=hello+world%21 will yield the following output

hello world!

The nginx standard $arg_PARAMETER variable holds the raw (escaped) value of the URI parameter. So we need the set_unescape_uri directive to unescape it first.

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $key $arg_key;
        set_unescape_uri $key;
 
        echo $key;
    }

then request GET /test?key=hello+world%21 will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_escape_uri

syntax: set_escape_uri $dst <src>

syntax: set_escape_uri $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

Very much like the set_unescape_uri directive, but does the conversion the other way around, i.e., URL component escaping.

set_hashed_upstream

syntax: set_hashed_upstream $dst <upstream_list_name> <src>

default: no

context: location, location if

phase: rewrite

Hashes the string argument <src> into one of the upstream name included in the upstream list named <upstream_list_name>. The hash function being used is simple modulo.

Here's an example,

    upstream moon { ... }
    upstream sun { ... }
    upstream earth { ... }
 
    upstream_list universe moon sun earth;
 
    location /test {
        set_unescape_uri $key $arg_key;
        set $list_name universe;
        set_hashed_upstream $backend $list_name $key;
 
        echo $backend;        
    }

Then GET /test?key=blah will output either "moon", "sun", or "earth", depending on the actual value of the key query argument.

This directive is usually used to compute an nginx variable to be passed to HttpMemcModule's memc_pass directive, HttpRedis2Module's HttpRedis2Module#redis2_pass directive, and HttpProxyModule's proxy_pass directive, among others.

set_encode_base32

syntax: set_encode_base32 $dst <src>

syntax: set_encode_base32 $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will encode the value of the second argument <src> to its base32(hex) digest and assign the result into the first argument, variable $dst. For example,

    location /test {
        set $raw "abcde";
        set_encode_base32 $digest $raw;
 
        echo $digest;
    }

Then request GET /test will yield the following output

c5h66p35

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

RFC forces the [A-Z2-7] RFC-3548 compliant encoding, but we're using the "base32hex" encoding ([0-9a-v]).

By default, the = character is used to pad the left-over bytes due to alignment. But the padding behavior can be completely disabled by setting set_misc_base32_padding off.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "abcde";
        set_encode_base32 $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_misc_base32_padding

syntax: set_misc_base32_padding on|off

default: on

context: http, server, server if, location, location if

phase: no

This directive can control whether to pad left-over bytes with the "=" character when encoding a base32 digest by the set_encode_base32 directive.

set_decode_base32

syntax: set_decode_base32 $dst <src>

syntax: set_decode_base32 $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

Similar to the set_encode_base32 directive, but does exactly the the opposite operation, .i.e, decoding a base32(hex) digest into its original form.

set_encode_base64

syntax: set_encode_base64 $dst <src>

syntax: set_encode_base64 $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will encode the value of the second argument <src> to its base64 digest and assign the result into the first argument, variable $dst. For example,

    location /test {
        set $raw "abcde";
        set_encode_base64 $digest $raw;
 
        echo $digest;
    }

Then request GET /test will yield the following output

YWJjZGU=

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "abcde";
        set_encode_base64 $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_decode_base64

syntax: set_decode_base64 $dst <src>

syntax: set_decode_base64 $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

Similar to the set_encode_base64 directive, but does exactly the the opposite operation, .i.e, decoding a base64 digest into its original form.

set_encode_hex

syntax: set_encode_hex $dst <src>

syntax: set_encode_hex $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will encode the value of the second argument <src> to its hexadecimal digest and assign the result into the first argument, variable $dst. For example,

    location /test {
        set $raw "章亦春";
        set_encode_hex $digest $raw;
 
        echo $digest;
    }

Then request GET /test will yield the following output

e7aba0e4baa6e698a5

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "章亦春";
        set_encode_hex $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_decode_hex

syntax: set_decode_hex $dst <src>

syntax: set_decode_hex $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

Similar to the set_encode_hex directive, but does exactly the the opposite operation, .i.e, decoding a hexadecimal digest into its original form.

set_sha1

syntax: set_sha1 $dst <src>

syntax: set_sha1 $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will encode the value of the second argument <src> to its SHA-1 digest and assign the result into the first argument, variable $dst. The hexadecimal form of the SHA-1 digest will be generated automatically, use set_decode_hex to decode the result if you want the binary form of the SHA-1 digest.

For example,

    location /test {
        set $raw "hello";
        set_sha1 $digest $raw;
 
        echo $digest;
    }

Then request GET /test will yield the following output

aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "hello";
        set_sha1 $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_md5

syntax: set_md5 $dst <src>

syntax: set_md5 $dst

default: no

context: location, location if

phase: rewrite

category: ndk_set_var_value

When taking two arguments, this directive will encode the value of the second argument <src> to its MD5 digest and assign the result into the first argument, variable $dst. The hexadecimal form of the MD5 digest will be generated automatically, use set_decode_hex to decode the result if you want the binary form of the MD5 digest.

For example,

    location /test {
        set $raw "hello";
        set_md5 $digest $raw;
 
        echo $digest;
    }

Then request GET /test will yield the following output

5d41402abc4b2a76b9719d911017c592

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

When taking a single argument, this directive will do in-place modification of the argument variable. For example,

    location /test {
        set $value "hello";
        set_md5 $value;
 
        echo $value;
    }

then request GET /test will give exactly the same output as the previous example.

This directive can be invoked by HttpLuaModule's ndk.set_var.DIRECTIVE interface and HttpArrayVarModule's array_map_op directive.

set_hmac_sha1

syntax: set_hmac_sha1 $dst <secret_key> <src>

syntax: set_hmac_sha1 $dst

default: no

context: location, location if

phase: rewrite

Computes the HMAC-SHA1 digest of the argument <src> and assigns the result into the argument variable $dst with the secret key <secret_key>.

The raw binary form of the HMAC-SHA1 digest will be generated, use set_encode_base64, for example, to encode the result to a textual representation if desired.

For example,

    location /test {
        set $secret 'thisisverysecretstuff';
        set $string_to_sign 'some string we want to sign';
        set_hmac_sha1 $signature $secret $string_to_sign;
        set_encode_base64 $signature $signature;
        echo $signature;
    }

Then request GET /test will yield the following output

R/pvxzHC4NLtj7S+kXFg/NePTmk=

Please note that we're using HttpEchoModule's echo directive here to output values of nginx variables directly.

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

set_random

syntax: set_random $res <from> <to>

default: no

context: location, location if

phase: rewrite

Generates a (pseudo) random number (in textual form) within the range [<$from>, <$to>] (inclusive).

Only non-negative numbers are allowed for the <from> and <to> arguments.

When <from> is greater than <to>, their values will be exchanged accordingly.

For instance,

    location /test {
        set $from 5;                              
        set $to 7;                                
        set_random $res $from $to;                
 
        echo $res;                                
    }

then request GET /test will output a number between 5 and 7 (i.e., among 5, 6, 7).

For now, there's no way to configure a custom random generator seed.

Behind the scene, it makes use of the standard C function rand().

This directive was first introduced in the v0.22rc1 release.

See also set_secure_random_alphanum and set_secure_random_lcalpha.

set_secure_random_alphanum

syntax: set_secure_random_alphanum $res <length>

default: no

context: location, location if

phase: rewrite

Generates a cryptographically-strong random string <length> characters long with the alphabet [a-zA-Z0-9].

<length> may be between 1 and 64, inclusive.

For instance,

    location /test {
        set_secure_random_alphanum $res 32;
 
        echo $res;
    }

then request GET /test will output a string like ivVVRP2DGaAqDmdf3Rv4ZDJ7k0gOfASz.

This function depends on the presence of the /dev/urandom device, available on most UNIX-like systems.

See also set_secure_random_lcalpha and set_random.

This directive was first introduced in the v0.22rc8 release.

set_secure_random_lcalpha

syntax: set_secure_random_lcalpha $res <length>

default: no

context: location, location if

phase: rewrite

Generates a cryptographically-strong random string <length> characters long with the alphabet [a-z].

<length> may be between 1 and 64, inclusive.

For instance,

    location /test {
        set_secure_random_lcalpha $res 32;
 
        echo $res;
    }

then request GET /test will output a string like kcuxcddktffsippuekhshdaclaquiusj.

This function depends on the presence of the /dev/urandom device, available on most UNIX-like systems.

This directive was first introduced in the v0.22rc8 release.

See also set_secure_random_alphanum and set_random.

set_rotate

syntax: set_rotate $value <from> <to>

default: no

context: location, location if

phase: rewrite

Increments $value but keeps it in range from <from> to <to>. If $value is greater than <to> or less than <from> is will be set to <from> value.

The current value after running this directive will always be saved on a per-location basis. And the this saved value will be used for incrementation when the $value is not initialized or has a bad value.

Only non-negative numbers are allowed for the <from> and <to> arguments.

When <from> is greater than <to>, their values will be exchanged accordingly.

For instance,

    location /rotate {
        default_type text/plain;
        set $counter $cookie_counter;
        set_rotate $counter 1 5;
        echo $counter;
        add_header Set-Cookie counter=$counter;
    }

then request GET /rotate will output next number between 1 and 5 (i.e., 1, 2, 3, 4, 5) on each refresh of the page. This directive may be userful for banner rotation purposes.

Another example is to use server-side value persistence to do simple round-robin:

    location /rotate {
        default_type text/plain;
        set_rotate $counter 0 3;
        echo $counter;
    }

And accessing /rotate will also output integer sequence 0, 1, 2, 3, 0, 1, 2, 3, and so on.

This directive was first introduced in the v0.22rc7 release.

set_local_today

syntax: set_local_today $dst

default: no

context: location, location if

phase: rewrite

Set today's date ("yyyy-mm-dd") in localtime to the argument variable $dst.

Here's an example,

    location /today {
        set_local_today $today;
        echo $today;
    }

then request GET /today will output something like

2011-08-16

and year, the actual date you get here will vary every day ;)

Behind the scene, this directive utilizes the ngx_time API in the Nginx core, so usually no syscall is involved due to the time caching mechanism in the Nginx core.

Caveats

Do not use $arg_PARAMETER, $cookie_COOKIE, $http_HEADER or other special variables defined in the Nginx core module as the target variable in this module's directives. For instance,

    set_if_empty $arg_user 'foo';  # DO NOT USE THIS!

may lead to segmentation faults.

Installation

Grab the nginx source code from nginx.org, for example, the version 1.0.15 (see nginx compatibility), and then build the source with this module:

    wget 'http://nginx.org/download/nginx-1.0.15.tar.gz'
    tar -xzvf nginx-1.0.15.tar.gz
    cd nginx-1.0.15/
 
    # Here we assume you would install you nginx under /opt/nginx/.
    ./configure --prefix=/opt/nginx \
        --with-http_ssl_module \
        --add-module=/path/to/ngx_devel_kit \
        --add-module=/path/to/set-misc-nginx-module
 
    make -j2
    make install

Download the latest version of the release tarball of this module from set-misc-nginx-module file list, and the latest tarball for ngx_devel_kit from its file list.

Also, this module is included and enabled by default in the ngx_openresty bundle.

Compatibility

The following versions of Nginx should work with this module:

  • 1.1.x (last tested: 1.1.5)
  • 1.0.x (last tested: 1.0.15)
  • 0.9.x (last tested: 0.9.4)
  • 0.8.x (last tested: 0.8.54)
  • 0.7.x >= 0.7.46 (last tested: 0.7.68)

If you find that any particular version of Nginx above 0.7.46 does not work with this module, please consider reporting a bug.

Report Bugs

Although a lot of effort has been put into testing and code tuning, there must be some serious bugs lurking somewhere in this module. So whenever you are bitten by any quirks, please don't hesitate to

  1. send a bug report or even patches to <agentzh@gmail.com>,
  2. or create a ticket on the issue tracking interface provided by GitHub.

Source Repository

Available on github at agentzh/set-misc-nginx-module.

ChangeLog

Test Suite

This module comes with a Perl-driven test suite. The test cases are declarative too. Thanks to the Test::Nginx module in the Perl world.

To run it on your side:

    $ PATH=/path/to/your/nginx-with-set-misc-module:$PATH prove -r t

You need to terminate any Nginx processes before running the test suite if you have changed the Nginx server binary.

Because a single nginx server (by default, localhost:1984) is used across all the test scripts (.t files), it's meaningless to run the test suite in parallel by specifying -jN when invoking the prove utility.

Getting involved

You'll be very welcomed to submit patches to the author or just ask for a commit bit to the source repository on GitHub.

Author

agentzh (章亦春) <agentzh@gmail.com>

This wiki page is also maintained by the author himself, and everybody is encouraged to improve this page as well.

Copyright & License

Copyright (c) 2009, 2010, 2011, Taobao Inc., Alibaba Group ( http://www.taobao.com ).

Copyright (c) 2009, 2010, 2011, Zhang "agentzh" Yichun (章亦春) <agentzh@gmail.com>.

This module is licensed under the terms of the BSD license.

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.

See Also