Change async behaviour of replicate and other commands

[hschne]

First of all: Kickass gem, thanks for creating it! I'm surprised this has only 200 stars. You'd think with everyone using SQLite in their new Rails apps a lot more people would use this too 🤷

Anyways. This addresses #42 and some other issues related to running Litestream rake tasks. The existing implementation would run any command as a forked process. This leads to problems when running replication from the command line or through Foreman.

# Forks the process and exits. Troublesome to stop on the command line, screws with Foreman and other process monitors
rails litestream:replicate 

The way I think about it, there are two types of Litestream commands: short-running ones and long-running ones. The only long-running command is replicate. Any other command will exit quickly, while replicate will keep running until terminated.

1. Short-running commands never need to be forked. We execute them, capture their output, and return.
2. replicate will be started as a fork or in the same process, depending on the context. Puma will start replication as a forked process, while the rake tasks don't. When running in-process, we capture output continuously and write to stdout.

This separation allows for simplification of arguments. We no longer need the async: true for short-running commands. Table formatting is also simplified, as most short-running commands output a tabular format. The only exception is the restore command.

Short-running commands now always return a hash, which is converted to a tabular output in the Rake task and then printed.

Testing

I gave my fork a go with one of my apps, running the various rake tasks, running in Puma, and so on. Caught a bunch of issues, hopefully got them all.

Other Changes

• Had to update to Rails 8 as dev dependency because I got a sqlite3 conflict (?) when trying to run tests 🤷
• Removed logfmt, because we don't need it anymore (?). Also removed superfluous sqlite3 development dependency.
• Updated standardrb to minimum Ruby version matching the gemspec
• Added a small bit to the readme on how to download litestream executables, because that tripped me up.
• Extracted argument parsing in the rake task

If you'd rather have a separate PR for the various little bits let me know, happy to take them out and move to a separate PR.

[fractaledmind]

I have some questions. I like the idea and certainly want to improve this area, but I don't fully grok everything yet.

[fractaledmind]

This feels like it should be a code comment somewhere appropriate:

replicate will be started as a fork or in the same process, depending on the context. Puma will start replication as a forked process, while the rake tasks don't. When running in-process, we capture output continuously and write to stdout.

[hschne]

Thanks for the great suggestions! Good call on the comment, moved it to the replicate command method.

I have some questions. I like the idea and certainly want to improve this area, but I don't fully grok everything yet

Sure thing! Let me know how I can help 🙌

[fractaledmind]

Released in v0.14.0