TYPO3 Core

If you have multiple redis containers with replications you will want to read from one redis instance and write to the other.
At the moment, the TYPO3 redis caching backend doesn't support configuring separate connectivity configuration for read and write.

Suggestion:

The possibility to configure one connection should be kept as it is for simplicity and backwards compatibility. Additionally the keys read and write can override individual options of the default connection.

SYS:
  caching:
    cacheConfigurations:
      extbase:
        backend: '\TYPO3\CMS\Core\Cache\Backend\RedisBackend'
        options:
          defaultLifetime: 31536000
          hostname: '%env(REDIS_REPLICA)%'
          port: 6379
          database: 0
          write:
            hostname: '%env(REDIS_MASTER)%'