[jamiesonbecker]

Exactly. Write-through cache is exactly how Userify[0] used to work for self-hosted versions. (when it was Python, we used Redis to keep state synced across multiple processes, but now that it's a Go app, we do all the caching and state management in memory using Ristretto[1])

However, we now install by default to local disk filesystem, since it's much faster to just do a periodic S3 hot sync, like with restic or aws-cli, than to treat S3 as the primary backing store, or just version the EBS or instance volume. The other reason you might want to use S3 as a primary is if you use a lot of disk, but our files are compressed and extremely small, even for a large installation with tens of thousands of users and instances.

0. https://userify.com (ssh key management + sudo for teams)

1. https://github.com/dgraph-io/ristretto

[avinassh]

What were the reasons to move from Redis to Ristretto? Both seem to be very different, since Redis is distributed where as Ristretto is local to the process.

[jamiesonbecker]

In our case, Python (because of the GIL) required us to have a single python process per core in order to take advantage of multiple cores, and so we needed Redis to maintain a unified memory state across all the cores, but Go can automatically span across multiple cores.

We also saw about a 10x speedup by moving all caching into the server process, and since it was all in the same process, we no longer had to compress and encrypt data before sending to Redis. We still checkpoint the moving server state, encrypted and compressed, to disk every sixty seconds, just like Redis would do with BGSAVE, so we can start back up within a few seconds (actually faster than the old Redis after a restart.)