Redis Cache for WordPress

A persistent cache backend powered by Redis.

Features

• Enables the two cache wrappers for WordPress
  • Object Cache (object-cache.php)
  • Advanced Page Cache (advanced-cache.php)
• Adds handy WP-CLI commands
  • wp redis status: Show the Redis cache status and (when possible) client.
  • wp redis flush: Flush the Redis cache, clear all data.
• Supports major PHP Redis drivers
  • Predis
  • PhpRedis (PECL)
• Supports replication and clustering
• Targets modern software stacks

Installation

• Prepare your Composer file by adding custom paths (more info)

  {
    "extra": {
      "dropin-paths": {
        "htdocs/wp-content/": [
          "package:leocolomb/wp-redis:dropins/object-cache.php",
          "package:leocolomb/wp-redis:dropins/advanced-cache.php"
        ]
      }
    }
  }

• Require the package in your Composer-managed WordPress instance

  $ composer require leocolomb/wp-redis

Configuration

To adjust the configuration, define any of the following constants in your wp-config.php file.

Connection

By default the object cache drop-in will connect to Redis over TCP at 127.0.0.1:6379 and select database 0.

Constant name	Default value	Description
WP_REDIS_CLIENT	not set	Specifies the client used to communicate with Redis. Supports pecl and predis.
WP_REDIS_SCHEME	tcp	Specifies the protocol used to communicate with an instance of Redis. Internally the client uses the connection class associated to the specified connection scheme. Supports tcp (TCP/IP), unix (UNIX domain sockets), tls (transport layer security) or http (HTTP protocol through Webdis).
WP_REDIS_HOST	127.0.0.1	IP or hostname of the target server. This is ignored when connecting to Redis using UNIX domain sockets.
WP_REDIS_PORT	6379	TCP/IP port of the target server. This is ignored when connecting to Redis using UNIX domain sockets.
WP_REDIS_PATH	not set	Path of the UNIX domain socket file used when connecting to Redis using UNIX domain sockets.
WP_REDIS_DATABASE	0	Accepts a numeric value that is used to automatically select a logical database with the SELECT command.
WP_REDIS_PASSWORD	not set	Accepts a value used to authenticate with a Redis server protected by password with the AUTH command.

Parameters

Constant name	Default value	Description
WP_CACHE_KEY_SALT	not set	Set the prefix for all cache keys. Useful in setups where multiple installs share a common wp-config.php or $table_prefix, to guarantee uniqueness of cache keys.
WP_REDIS_MAXTTL	not set	Set maximum time-to-live (in seconds) for cache keys with an expiration time of 0.
WP_REDIS_GLOBAL_GROUPS	['blog-details', 'blog-id-cache', 'blog-lookup', 'global-posts', 'networks', 'rss', 'sites', 'site-details', 'site-lookup', 'site-options', 'site-transient', 'users', 'useremail', 'userlogins', 'usermeta', 'user_meta', 'userslugs']	Set the list of network-wide cache groups that should not be prefixed with the blog-id (Multisite only).
WP_REDIS_IGNORED_GROUPS	['counts', 'plugins']	Set the cache groups that should not be cached in Redis.
WP_REDIS_IGBINARY	not set	Set to true to enable the igbinary serializer.

Page cache

Constant name	Default value	Description
WP_CACHE	false	Set to true to enable advanced page caching. If not set, the Redis page cache will not be used.
WP_REDIS_TIMES	2	Only cache a page after it is accessed this many times.
WP_REDIS_SECONDS	120	Only cache a page if it is accessed $times in this many seconds. Set to zero to ignore this and use cache immediately.
WP_REDIS_MAXAGE	300	Expire cache items aged this many seconds. Set to zero to disable cache.
WP_REDIS_GROUP	'redis-cache'	Name of object cache group used for page cache.
WP_REDIS_UNIQUE	[]	If you conditionally serve different content, put the variable values here using the add_variant() method.
WP_REDIS_HEADERS	[]	Add headers here as name => value or name => [values]. These will be sent with every response from the cache.
WP_REDIS_UNCACHED_HEADERS	['transfer-encoding']	These headers will never be cached. (Use lower case only!)
WP_REDIS_CACHE_CONTROL	true	Set to false to disable Last-Modified and Cache-Control headers.
WP_REDIS_USE_STALE	true	Is it ok to return stale cached response when updating the cache?
WP_REDIS_NOSKIP_COOKIES	['wordpress_test_cookie']	Names of cookies - if they exist and the cache would normally be bypassed, don't bypass it.

Replication & Clustering

To use Replication and Clustering, make sure your server is running PHP7, your setup is using Predis to connect to Redis and you consulted the Predis documentation.

For replication use the WP_REDIS_SERVERS constant and for clustering the WP_REDIS_CLUSTER constant. You can use a named array or an URI string to specify the parameters.

For authentication use the WP_REDIS_PASSWORD constant.

Master-Slave Replication

define('WP_REDIS_SERVERS', [
    'tcp://127.0.0.1:6379?database=15&alias=master',
    'tcp://127.0.0.2:6379?database=15&alias=slave-01',
]);

Clustering via Client-side Sharding

define('WP_REDIS_CLUSTER', [
    'tcp://127.0.0.1:6379?database=15&alias=node-01',
    'tcp://127.0.0.2:6379?database=15&alias=node-02',
]);

License

GPL-3.0 © Léo Colombaro

• Eric Mann and Erick Hitter for Redis Object Cache
• Till Krüss for tillkruss/redis-cache