Adding json support for log-format config

[jbergstroem]

Introduce a json log format that can be invoked by passing log-format json in your config.

We also refactor escapeJsonString to util since it is now a shared function.

Closes: #1006

[jbergstroem]

The DCO action is confusing:

Summary

Commit sha: d8edd52, Author: Johan Bergström, Committer: Johan Bergström; Expected "Johan Bergström bugs@bergstroem.nu", but got "Johan Bergström bugs@bergstroem.nu".

Edit: Fixed. I think it was complaining about using the wrong representation of ö in my last name.

[codecov]

Codecov Report

❌ Patch coverage is 86.95652% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.90%. Comparing base (e179fdd) to head (f2a8155).
⚠️ Report is 18 commits behind head on unstable.

Files with missing lines	Patch %	Lines
src/server.c	77.77%	2 Missing ⚠️
src/util.c	92.85%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #1791      +/-   ##
============================================
+ Coverage     73.81%   73.90%   +0.09%     
============================================
  Files           125      125              
  Lines         69347    69353       +6     
============================================
+ Hits          51187    51256      +69     
+ Misses        18160    18097      -63     

Files with missing lines	Coverage Δ
src/cli_common.c	62.91% <ø> (+1.09%)	⬆️
src/config.c	78.76% <ø> (ø)
src/server.h	100.00% <ø> (ø)
src/valkey-cli.c	56.78% <ø> (-0.09%)	⬇️
src/util.c	66.66% <92.85%> (+0.49%)	⬆️
src/server.c	88.76% <77.77%> (+0.05%)	⬆️

... and 14 files with indirect coverage changes

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[zuiderkwast]

Nice to see this has been started.

We need to escape the strings. There's some code for that in cli_common.c:

sds escapeJsonString(sds s, const char *p, size_t len);

We could move it to another file like util.c, since it will no longer be only for the CLI.

[jbergstroem]

Nice to see this has been started.

We need to escape the strings. There's some code for that in cli_common.c:

sds escapeJsonString(sds s, const char *p, size_t len);

We could move it to another file like util.c, since it will no longer be only for the CLI.

Makes sense. Would be much more comfortable if I could test this as we go. Should we start a unit test for basic functions?

[zuiderkwast]

Would be much more comfortable if I could test this as we go. Should we start a unit test for basic functions?

Yes, we can do that. Another option is to add an integration test where do something that causes something to be logged and then verify what's logged in the log file.

Grep for verify_log_message to find tests that already do this.

We can use the command DEBUG LOG message to write to the log. The server needs to be started with --enable-debug-command yes but that's enabled in the tests already.

[jbergstroem]

@zuiderkwast long time since last update -- apologies; life came in-between. I've done the changes you requested (refactor, add tests). Will make it ready for review. Finally – if there is places that lacks documentation, feel free to point me to them. Thanks for any feedback!

[zuiderkwast]

LGTM

@valkey-io/core-team When we decided to add the logfmt format in #1022 (comment), it appears we also already agreed to add the JSON log format. Please comment if you don't agree.

[enjoy-binbin]

LGTM.

[zuiderkwast]

Thanks Johan!