Best practices for Redis service configuration

• Configure Redis L2 cache
• Enable Redis slave connection
• Pre-load keys
• Enable stale cache
• Separate the Redis cache from the Redis session
• Compress the Redis cache and use gzip for higher compression

Configure Redis L2 cache

Configure the Redis L2 cache by setting the REDIS_BACKEND deployment variable in the .magento.env.yaml configuration file.

stage:
  deploy:
    REDIS_BACKEND: '\Magento\Framework\Cache\Backend\RemoteSynchronizedCache'

For environment configuration on Cloud infrastructure, see the REDIS_BACKEND in the Commerce on Cloud Infrastructure Guide.

For on-premises installations, see Configure Redis page caching in the Configuration Guide.

Enable Redis slave connection

Enable a Redis slave connection in the .magento.env.yaml configuration file to allow only one node to handle read-write traffic while the other nodes handle the read-only traffic.

stage:
  deploy:
    REDIS_USE_SLAVE_CONNECTION: true

See REDIS_USE_SLAVE_CONNECTION in the Commerce on Cloud Infrastructure Guide.

For Adobe Commerce on-premises installations, configure the new Redis cache implementation using the bin/magento:setup commands. See Use Redis for default cache in the Configuration Guide.

Pre-load keys

To reuse data between pages, list the keys for preload in the .magento.env.yaml configuration file.

stage:
  deploy:
    REDIS_BACKEND: '\Magento\Framework\Cache\Backend\RemoteSynchronizedCache'
    CACHE_CONFIGURATION:
      _merge: true
      frontend:
        default:
          id_prefix: '061_'                       # Prefix for keys to be preloaded
          backend_options:
            preload_keys:                         # List the keys to be preloaded
              - '061_EAV_ENTITY_TYPES:hash'
              - '061_GLOBAL_PLUGIN_LIST:hash'
              - '061_DB_IS_UP_TO_DATE:hash'
              - '061_SYSTEM_DEFAULT:hash'

For on-premises installations, see Redis preload feature in the Configuration Guide.

Enable stale cache

Reduce lock waiting times and enhance performance—especially when dealing with numerous Blocks and Cache keys—by using an outdated cache while generating a new cache in parallel. Enable stale cache and define cache types in the .magento.env.yaml configuration file:

stage:
  deploy:
    REDIS_BACKEND: '\Magento\Framework\Cache\Backend\RemoteSynchronizedCache'
    CACHE_CONFIGURATION:
      _merge: true
      default:
        backend_options:
          use_stale_cache: false
      stale_cache_enabled:
        backend_options:
          use_stale_cache: true
      type:
        default:
          frontend: "default"
        layout:
          frontend: "stale_cache_enabled"
        block_html:
          frontend: "stale_cache_enabled"
        reflection:
          frontend: "stale_cache_enabled"
        config_integration:
          frontend: "stale_cache_enabled"
        config_integration_api:
          frontend: "stale_cache_enabled"
        full_page:
          frontend: "stale_cache_enabled"
        translate:
          frontend: "stale_cache_enabled"

For configuring on-premises installations, see Stale cache options in the Configuration Guide.

Separate Redis cache and session instances

Separating the Redis cache from Redis session allows you to manage the cache and sessions independently. It prevents cache issues from affecting sessions, which could impact revenue. Each Redis instance runs on its own core, which improves performance.

1. Update the .magento/services.yaml configuration file.

   mysql:
       type: mysql:10.4
       disk: 35000
   
   redis:
      type: redis:6.0
   
   redis-session:              # This is for the new Redis instance
      type: redis:6.0
   
   search:
      type: elasticsearch:7.9
      disk: 5000
   
   rabbitmq:
      type: rabbitmq:3.8
      disk: 2048
   

2. Update the .magento.app.yaml configuration file.

   relationships:
       database: "mysql:mysql"
       redis: "redis:redis"
       redis-session: "redis-session:redis"   # Relationship of the new Redis instance
       search: "search:elasticsearch"
       rabbitmq: "rabbitmq:rabbitmq"
   

3. Submit an Adobe Commerce Support ticket to request the provisioning of a new Redis instance dedicated to sessions on Production and Staging environments. Include the updated .magento/services.yaml and .magento.app.yaml configuration files. This won’t cause any downtime, but it requires a deployment to activate the new service.

4. Verify that the new instance is running and make a note of the port number.

   echo $MAGENTO_CLOUD_RELATIONSHIPS | base64 -d | json_pp
   

5. Add the port number to the .magento.env.yaml configuration file.

   NOTE

   disable_locking must be set to 1.

   SESSION_CONFIGURATION:
     _merge: true
     redis:
       port: 6374       # check the port in $MAGENTO_CLOUD_RELATIONSHIPS
       timeout: 5
       disable_locking: 1
       bot_first_lifetime: 60
       bot_lifetime: 7200
       max_lifetime: 2592000
       min_lifetime: 60
   

6. Remove sessions from the default database (db 0) on the Redis cache instance.

   redis-cli -h 127.0.0.1 -p 6374 -n 0 FLUSHDB
   

During deployment, you should see the following lines in the build and deploy log:

W:   - Downloading colinmollenhour/credis (1.11.1)
W:   - Downloading colinmollenhour/php-redis-session-abstract (v1.4.5)
...
W:   - Installing colinmollenhour/credis (1.11.1): Extracting archive
W:   - Installing colinmollenhour/php-redis-session-abstract (v1.4.5): Extracting archive
...
[2022-08-17 01:13:40] INFO: Version of service 'redis' is 6.0
[2022-08-17 01:13:40] INFO: Version of service 'redis-session' is 6.0
[2022-08-17 01:13:40] INFO: redis-session will be used for session if it was not override by SESSION_CONFIGURATION

Cache compression

If you are using over 6GB of Redis maxmemory, you can use cache compression to reduce the space consumed by the keys. Be aware that there is a trade-off with client-side performance. If you have spare CPUs, enable it. See Use Redis for session storage in the Configuration Guide.

stage:
  deploy:
    REDIS_BACKEND: '\Magento\Framework\Cache\Backend\RemoteSynchronizedCache'
    CACHE_CONFIGURATION:
      _merge: true;
      frontend:
        default:
          backend_options:
            compress_data: 4              # 0-9
            compress_tags: 4              # 0-9
            compress_threshold: 20480     # don't compress files smaller than this value
            compression_lib: 'gzip'       # snappy and lzf for performance, gzip for high compression (~69%)

Additional information

• Redis Page Cache
• Use Redis for session storage

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