Add redis backed cache implementation as alternative to infinispan

[StFS]

I think providing a Redis alternative for distributed caching solution in Hono in addition to the current Infinispan implementation would be beneficial in many ways.

First, many companies already have a Redis cluster available as opposed to Infinispan which is not nearly as widely used. Second, all the major cloud providers offer some sort of a managed Redis solution (ElastiCache, Azure Cache for Redis, Memorystore) which makes it much easier to set up a Redis cluster than setting up an Infinispan grid.

This ticket is mainly created for communication purposes and to serve as a hub for information gathering.

I may take a stab at creating a PR for this.

[StFS]

Current status of this issue is that the implementation is underway but has been split into two PRs:

• Preparation work by splitting the command-router modules up into "base" and "infinispan" modules
  • Split up command router modules #3623
• Actually adding a redis backe command-router implementation:
  • Add Redis backed Command Router controlant-org/eclipse-hono#4 (currently work in progress and depends on the above PR being merged, so this PR is not yet set to merge into eclipse-hono/hono)

[sophokles73]

BTW are you aware of the struggles around Redis forks: https://lwn.net/Articles/966631/

[StFS]

BTW are you aware of the struggles around Redis forks: https://lwn.net/Articles/966631/

Ugh... I was not.

Sounds like this is heading in a similar direction as MongoDB. At any rate, I don't really think it has much impact on my work on this. For now, different solutions haven't diverged much so I assume my implementation would be a good basis for chasing any Redis alternative (be it Valkey or something else). Probably, the deciding factor as is would be if the quarkus-redis-client extension got modified in such a way to not be compatible with some of these alternatives.

My objective with this is pretty clear: to support whatever variation of Redis that AWS ElastiCache uses. I think that would bring most value for Hono users as it's the largest cloud provider. My hope would be that Google and Microsoft would use the same variant as AWS but I guess that remains to be seen.

Would you say that this news should impact my work on this in any way? I would assume that license wise, it shouldn't make much of a difference since MongoDB is used in Hono and that has gone through similar changes.