Don't write all program output to .metals/metals.log

[ckipp01]

I was shocked to find out that my simple project almost without dependencies that just contains solutions for AoC tasks was taking around 500MB of space. Upon closer inspection turns out that there are almost half a gig of logs... I don't know if this is a bug or maybe I'm doing something wrong, so I'm not posting an issue yet, but this can't be right. Should I open an issue?

vijexa@DESKTOP-ETMRL27:~/advent-of-code-2020/advent-of-code-2020/.metals$ du -ahd 1
644K    ./metals.h2.db
488M    ./metals.log
804K    ./readonly
489M    .

Originally posted by @vijexa in #2309

And copying the response from @tgodzik

I think it's due to the fact that Bloop reports it when running, I think we should not write it to log, but I can't remember why it was done in the first place. This should become an issue really.

[ckipp01]

I looked into this a bit today and something I noticed was that this is actually Bloop specific. Even though the DAP communication seems to be the same, when using Bloop as a BSP server the output is logged out to INFO, but this doesn't happen when using sbt as a BSP server.

[vishalovercome]

Is the logging configurable? Libraries such as Testcontainers generate a lot of logs and running them as part of worksheets results in disks filling up very quickly. We need a cap on the size of the logs as well as log level configurability.

[tgodzik]

We should most likely not log to file at all, I don't think it's useful at any point. We need to fix it in Bloop itself though.

[vishalovercome]

While metals.log might not be the right place to log program output, we'll need to have some log file, logging configuring capability as that's the only way to debug our worksheets. I would also like to know whether you have a timeline in mind for this fix. Are we going to release it as part of v1.0.0 release?

[tgodzik]

Output from a program are normally logged to debug console, so that should be enough. As for worksheets, they should not be logged at all aside from errors, which is a normal Metals logging behaviour.

Timeline will probably be within next couple of months, because I think it's something we need to fix for sure before 1.0.0