Add JSON logging support using Go's slog library

[ChaturvediShilpa]

• Add JSONLeveledLogger and JSONLoggerFactory for structured JSON logging
• Support all log levels (TRACE, DEBUG, INFO, WARN, ERROR, DISABLED)
• Maintain backward compatibility with existing text logging
• Add comprehensive tests for JSON logging functionality
• Update documentation with usage examples
• Require Go 1.21+ for slog library support

This change allows users to choose between text and JSON logging formats while maintaining the same API and functionality.

Description

Reference issue

Closes #127

[Sean-Der]

Would it better to deprecate pion/logging entirely? Now that slog exists this is just cruft/indirection I believe

[JoTurk]

Would it better to deprecate pion/logging entirely? Now that slog exists this is just cruft/indirection I believe

Maybe when we upgrade to 1.21?

[rg0now]

I'd love to get this or a similar functionality merged (I haven't reviewed the code yet). Structured logging is one of the most requested features in STUNner given how pretty much everything in the Kubernetes ecosystem is built around this logging style.

Maybe we could save this PR by using/writing some slog replacement/wrapper that works with Golang v1.20 for the time pion is stuck at that Go version, and then transitioning to the official slog package once we make the switch. But we could also choose whatever structured logging lib we see fit. Of course, this will still be a half-solution only, given how pion/logging is built-around Printf style logging to format parameters, which is in fundamental violation of the philosophy of structured logging.

That being said, deprecating pion/logging would put a pretty high burden on upstream projects that depend on it. I'm not saying we shouldn't do that, but I believe we should definitely have some smoother upgrade path in place before we make that move, like the compatibility layer suggested in this PR.

[JoTurk]

Maybe we could save this PR by using/writing some slog replacement/wrapper that works with Golang v1.20 for the time pion is stuck at that Go version, and then transitioning to the official slog package once we make the switch. But we could also choose whatever structured logging lib we see fit. Of course, this will still be a half-solution only, given how pion/logging is built-around Printf style logging to format parameters, which is in fundamental violation of the philosophy of structured logging.

I like this idea, I can contribute to this, if we go with this idea.

[JoTurk]

@ChaturvediShilpa Hello we upgraded to go 1.21, do you wanna get this merged?

[JoTurk]

Do you want to fix the errors in the compile example so we can merge this? otherwise i can fix them myself.
Thank you.

[JoTurk]

Wouldn't this lead to duplicated levels?

[codecov]

Codecov Report

❌ Patch coverage is 80.64516% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.36%. Comparing base (32a8ea5) to head (a70ea01).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
json_logger.go	80.64%	23 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #126      +/-   ##
==========================================
- Coverage   98.33%   88.36%   -9.97%     
==========================================
  Files           2        3       +1     
  Lines         120      275     +155     
==========================================
+ Hits          118      243     +125     
- Misses          1       24      +23     
- Partials        1        8       +7     

Flag	Coverage Δ
go	88.36% <80.64%> (-9.97%)	⬇️

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[rg0now]

Overall, I really like this. I think the JSONLoggerFactory will be a really nice drop-in replacement for people who insist on structured logging without having to change anything in the rest of the code depending on pion/logging. Just to make sure that *JSONLoggerFactory is a proper LoggerFactory, can you add an assertion like the below to json_logger.go?

var _ LoggerFactory = NewJSONLoggerFactory()

Apart, I think (to the extent I could review the code) this can be merged.

[JoTurk]

@rg0now yeah we talked (me and @philipch07 ) about making sure that JSONLoggerFactory is LoggerFactory before merging this. @philipch07 asked me to do it and i was doing it tonight.

[JoTurk]

Also making all the unnecessary interfaces / structs private.

[JoTurk]

@philipch07 @rg0now I pushed a commit to private everything that we don't need, added a LoggerFactory interface, made sure we make LeveledLogger. can you please give it a review when you have time?

[philipch07]

Thanks for cleaning it up! It looks good to me :)

[JoTurk]

@rg0now does this look good to you?

[JoTurk]

@rg0now I'm going to test the logging factory again before tagging this, but i think it should be drop in replacement now.

thank you @ChaturvediShilpa @philipch07

[rg0now]

Sorry, missed this thread. This was a long-standing issue and I'm really happy it finally got fixed. Thanks!