Keyval

The module allows the use of variables with values from "key-value" pairs, which are stored in shared memory or in a Redis store.

Loading the Module

To work with the module, it must be loaded in the context of main{}:

load_module modules/ngx_http_keyval_module.so;

Configuration Example

keyval_zone zone=one:32k;
keyval $arg_key $value zone=one;

server {
    listen 80;
    server_name localhost;

    location /get {
        return 200 "key '$arg_key' has value = '$value'\\n";
    }

    location /set {
        set $value $arg_value;
        return 200 "'$arg_key' key added with '$arg_value' value\\n";
    }
}

Adding and modifying entries in the shared memory zone 'one' is done by assigning a value to the variable $value. The key's value is stored in the variable $arg_key. In this configuration, this is the directive set:

set $value $arg_value;

Demonstration

Let's define some values using requests:

$ curl "localhost/set/?key=one&value=TextForKeyOne"

  'one' key added with 'TextForKeyOne' value

$ curl "localhost/set/?key=two&value=TextForKeyTwo"

  'two' key added with 'TextForKeyTwo' value

Let's check:

$ curl "localhost/get/?key=one"

  key 'one' has value = 'TextForKeyOne'

$ curl "localhost/get/?key=two"

  key 'two' has value = 'TextForKeyTwo'

Using Redis

Let's modify the configuration to store "key-value" pairs in a Redis store:

keyval_zone_redis zone=oneredis;
keyval $arg_key $value zone=oneredis;

server {
    listen 80;
    server_name localhost;

    location /get {
        return 200 "key '$arg_key' has value = '$value'\\n";
    }

    location /set {
        set $value $arg_value;
        return 200 "'$arg_key' key added with '$arg_value' value\\n";
    }
}

Let's add a "key-value" pair to the Redis store via a request:

$ curl "localhost/set/?key=one&value=TextForKeyOne"

  'one' key added with 'TextForKeyOne' value

The same can be done using Redis itself:

$ redis-cli

  127.0.0.1:6379> set oneredis:two 'text for key two'

  OK

  127.0.0.1:6379>

Let's check:

$ redis-cli --scan

  "oneredis:one"
  "oneredis:two"

$ curl "localhost/get/?key=one"

  key 'one' has value = 'TextForKeyOne'

$ curl "localhost/get/?key=two"

  key 'two' has value = 'text for key two'

Additional Information

A complete description of the directives and the source code is available at: kjdev/nginx-keyval.