1. Docs
2. Advanced
3. Using Redis or Valkey

Using Redis or Valkey

Shlink can take advantage of a shared cache server like redis or valkey in multiple contexts.

• For caching purposes.
• To store shared locks.
• To publish real-time updates via Pub/Sub.

Caching purposes

Shlink can persist certain things in a faster storage for quick access.

By default, it uses APCu if available (when using a classic web server) or in-memory (when using Roadrunner as the runtimes), but it can be provided with some shared cache server access configuration.

When doing so, Shlink will use it as the cache persistence.

Shared locks

If you plan to run multiple Shlink instances, it’s important to make sure the so-called “locks” are shared between all of them.

A shared cache server is a good way to do so. If Shlink is provided with access configuration, it will use it to store shared locks.

Supported capabilities

Shlink supports multiple shared cache server capabilities. They can be enabled by providing different connection URIs:

• Single instance (Redis / Valkey), when providing just one server (for example, tcp://my_redis_server:6379).
• Cluster (Redis / Valkey), when providing multiple servers (for example, tcp://one_redis_server:6379,tcp://another_redis_server:6379).
• Sentinels (Redis / Valkey), when providing multiple servers, together with a sentinel service name.
• Database selection (since Shlink 4.2.1), by providing the database index in the URI path (for example, tcp://my_redis_server:6379/5).
• Credentials, that can be provided as part of the server URIs:
  • ACL, with username and password (Redis / Valkey): tcp://the_username:the_password@my_redis_server:6379
  • Legacy, with just password (Redis / Valkey): tcp://:the_password@my_redis_server:6379.

Providing configuration

As with any other configuration params, there are two main ways to provide shared cache server options:

• Environment variables, which allow you to enable the integration however you like.

• The installation tool, which will, at some point, ask you if you want to integrate with redis, and request you to provide all the capabilities above if so.

   [...]
  
  INTEGRATIONS
  ============
  
   Do you want to use a redis instance, redis cluster or redis sentinels as a shared cache for Shlink? (recommended if you run a cluster of Shlink instances) (yes/no) [no]:
   > yes
  
   Provide a comma-separated list of URIs (redis servers/sentinel instances):
   > tcp://one_redis_server:6379,tcp://another_redis_server:6379
  
   Provide the name of the sentinel service (leave empty if not using redis sentinel):
   >
  
   Do you want Shlink to publish real-time updates in this Redis instance/cluster? (yes/no) [no]:
   > yes
  
   [...]