Hello here, I've raised the discussion on private@ and it seems that there are no private/controversies there, so I bring the discussion to devlist where it belongs.
You might want to be aware that Redis announced licensing changes that make future Redis 7.4+ releases not good for "mandatory" dependency of Airflow. [1]. This is a very similar move to one that MongoDB, Elasticsearch and Terraform did. The RSAL licence is explicitly mentioned in the "Category -X" [2] of 3rd-party licence policy by the ASF as not good as "mandatory" dependency - but still allowed as optional [3]. Redis client is MIT licensed and there are no plans to change that - so technically speaking we do not have to limit it in any way. My - personal - assessment is that we are not really affected - even with our Celery Executor, rabbitmq is still a viable alternative for Redis (not mentioning Local and Kubernetes executors), so redis is indeed an optional feature. In the future, someone could contribute Apache Qpid [4] (which is supported by Kombu), also an easier one to contribute is to add Valkey [5] as an alternative. In the meantime I created https://github.com/apache/airflow/pull/38928 to limit Redis image to 7-2-bookworm. Also I'd love personally to see someone to contribute direct Valkey support (that would be great I think) - but other than that I think there is not much we have to do now. But maybe others have different opinions and proposals (and would love to follow up on it) ? J. [1] https://redis.io/blog/redis-adopts-dual-source-available-licensing/ [2] https://www.apache.org/legal/resolved.html#category-x [3] https://www.apache.org/legal/resolved.html#optional [4] https://qpid.apache.org [5] https://www.linuxfoundation.org/press/linux-foundation-launches-open-source-valkey-community