Module ngx_http_keyval_module

The ngx_http_keyval_module module (1.13.3) creates variables with values taken from key-value pairs managed by the API or a variable (1.15.10) that can also be set with njs.

This module is available as part of our commercial subscription.

http {

    keyval_zone zone=one:32k state=/var/lib/nginx/state/one.keyval;
    keyval $arg_text $text zone=one;
    ...
    server {
        ...
        location / {
            return 200 $text;
        }

        location /api {
            api write=on;
        }
    }
}

Creates a new $variable whose value is looked up by the key in the key-value database. Matching rules are defined by the type parameter of the keyval_zone directive. The database is stored in a shared memory zone specified by the zone parameter.

Sets the name and size of the shared memory zone that keeps the key-value database. Key-value pairs are managed by the API.

The optional state parameter specifies a file that keeps the current state of the key-value database in the JSON format and makes it persistent across nginx restarts. Changing the file content directly should be avoided.

Examples:

keyval_zone zone=one:32k state=/var/lib/nginx/state/one.keyval; # path for Linux
keyval_zone zone=one:32k state=/var/db/nginx/state/one.keyval;  # path for FreeBSD

The optional timeout parameter (1.15.0) sets the time after which key-value pairs are removed from the zone.

The optional type parameter (1.17.1) activates an extra index optimized for matching the key of a certain type and defines matching rules when evaluating a keyval $variable.

The index is stored in the same shared memory zone and thus requires additional storage.

type=string

default, no index is enabled; variable lookup is performed using exact match of the record key and a search key

type=ip

the search key is the textual representation of IPv4 or IPv6 address or CIDR range; to match a record key, the search key must belong to a subnet specified by a record key or exactly match an IP address

type=prefix

variable lookup is performed using prefix match of a record key and a search key (1.17.5); to match a record key, the record key must be a prefix of the search key

The optional sync parameter (1.15.0) enables synchronization of the shared memory zone. The synchronization requires the timeout parameter to be set.

If the synchronization is enabled, removal of key-value pairs (no matter one or all) will be performed only on a target cluster node. The same key-value pairs on other cluster nodes will be removed upon timeout.