Let's hold off on this, Joe. I'm preparing a first "real" use of Redis for our current documentation reference cache. This sets up the infrastructure needed (although it's quite tied to this particular use case for the moment - for example, the nested Redis actor should move to the top level once I'm done testing this setup).

Sorry, I just realised I misread the point of this PR, see my comment here: #3582 (comment)

I think all we need to do is weave the Environment.get("REDIS_HOST") into the Redis actor where it's using the hard-coded string right now and then we're good.

First day I've been able to have any mental capacity to catch back up. Updated this PR to work over the main branch, still leaning into something to make redis available locally for dev work. Actor impl works perfectly, for me, but I wasn't entirely sure how you wanted to handle configuring it dynamically - I thought to reach for an environment variable, following the database host access pieces, but noticed that was also a dependency setup, and wasn't sure if dependencies in dependencies were even a thing, or if a straight processinfo access point inside the actor setup code would be acceptable.

@Dependency works inside a dependency and we should always aim to funnel side effects through them. I'll fix this up and update the Redis bit to work with these changes here.

Apologies for the delay Joe, I completely lost track of this one!

We should also add something to the LOCAL_DEVELOPMENT_SETUP.md file that explains in what circumstances and which bits of the code you'd need a Redis server and how to use the make commands.