Move from redis to valkey

[jcscottiii]

Our code uses an Cache interface so we just need to implement another implementation of the cache interface for valkey.

Most of the work is renaming everything from redis to valkey.

The tests that use an actual instance in lib/valkeycache/cache_test.go needed no modifications besides renaming.

With this, we can use the latest version of valkey: 8.0. Whereas it seems we are stuck on redis version 7.2 beforehand (redis has 7.4 out).

One thing that is notable, the valkey client uses strings and []byte. We tend to like []byte instead. So what I did was restrict this implementation to []byte values.

From a Terraform perspective, I just followed the examples from the docs. Previously, we had a 1GB instance. Now, we have a 1.4GB instance (via the SHARED_CORE_NANO node type). That is the smallest instance type. Pricing wise shouldn't really matter. The instance will be slightly cheaper (4 cents per hour vs 6 cents per hour). Valkey Pricing vs Redis Pricing. I think the network pricing will be the same based on usage.

[jrobbins]

Just curious, where can we see our cache hit ratio?

[jcscottiii]

Just curious, where can we see our cache hit ratio?

For Valkey, it appears in the monitoring tab of that particular instance: Here's an example.

For redis, it appears on the monitoring tab of that particular instance too: Here's an example

On a semi-related note:

The Redis dashboard by default has some more interesting charts like expired & evicted keys. I would check those out too. Valkey has those metrics but we just have to add the charts ourselves (I will add them to the existing main dashboard)