feat: adds support to group logs of the same http request

[simonz130]

With TraceLoggingEventEnhancer users can set the traceId of the incoming request and then all the logs that will be created on the same thread will have the traceId property set to that traceId. This allows Cloud Logging to group log entries from the same request in the UI for easier troubleshooting.

Example:

1. One time configuration (adding logging event enhancer to logs appender):

LoggingAppender cloudAppender = new LoggingAppender();
cloudAppender.addLoggingEventEnhancer("com.google.cloud.logging.logback.TraceLoggingEventEnhancer");

2. User's code (when receiving http request):

TraceLoggingEventEnhancer.setCurrentTraceId(
      "projects/" + GOOGLE_PROJECT_ID + "/traces/" + traceId);

3. Then just logging regularly:

LOGGER.info("XXX");

Then use grouping by traceId in Cloud Logging:

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #94 ☕️

[codecov]

Codecov Report

Merging #257 (899f68e) into master (5ad9f24) will increase coverage by 0.57%.
The diff coverage is 77.77%.

@@             Coverage Diff              @@
##             master     #257      +/-   ##
============================================
+ Coverage     68.05%   68.62%   +0.57%     
- Complexity       35       39       +4     
============================================
  Files             2        3       +1     
  Lines           144      153       +9     
  Branches         15       17       +2     
============================================
+ Hits             98      105       +7     
  Misses           33       33              
- Partials         13       15       +2     

Impacted Files	Coverage Δ	Complexity Δ
...oud/logging/logback/TraceLoggingEventEnhancer.java	77.77% <77.77%> (ø)	4.00 <4.00> (?)

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[chingor13]

Also, LGTM

[darewreck54]

@simonz130 / @chingor13 just to clarify, this means that I need to put

TraceLoggingEnhancer.setCurrentTraceId(
      "projects/" + GOOGLE_PROJECT_ID + "/traces/" + traceId);

in an interceptor that process every request that I get?

Thanks,
Derek

[darewreck54]

I'm still seeing the request thread TraceLoggingEnhancer trace id = null with upgrading to the 1.119.0-alpha. Perhaps i'm doing it wrong. I'm still seeing the log thread having the traceId as null while the request filter trace id being stored as mentioned in your previous thread. @simonz130

[darewreck54]

Isn't it suppose to be configured adding a label for stack driver to recognize it

   builder.addLabel("trace_id", traceId);

https://cloud.google.com/logging/docs/setup/java#flexible_environment?

[simonz130]

Hello @darewreck54, I realized that my PR description was not accurate - it didn't include instructions to add logging event appender for logback to use:

LoggingAppender cloudAppender = new LoggingAppender();
cloudAppender.addLoggingEventEnhancer("com.google.cloud.logging.logback.TraceLoggingEventEnhancer");

I just tested the code you provided earlier to illustrate what you wanted to achieve with request grouping, with the new feature introduced in this PR and it worked for me on AppEngine Flex.
We will update official documentation to include info about request logs grouping and I updated this PR's description.

[darewreck54]

@simonz130 I had another question. Is this library meant to be used service deployed in GKE? I noticed the recommended way is to pipe logs to stdout, but this approach pipes it to a file. https://cloud.google.com/solutions/best-practices-for-operating-containers#use_the_native_logging_mechanisms_of_containers

Any suggestion from that stand front?