JSON logging

[leonardehrenfried]

Summary

This allows users of OTP to switch to JSON-formatted logs by setting an command line parameter like this:

java -Dotp.logging.format=json -jar otp.jar --load --serve data

A (pretty-printed) example of a log message looks like this:

{
  "@timestamp": "2023-04-03T13:28:08.058026697+02:00",
  "level": "INFO",
  "logger_name": "org.opentripplanner.routing.graph.SerializedGraphObject",
  "thread_name": "main",
  "message": "Reading graph from 'tampere/graph.obj'"
}

I've also included Entur's configuration in this PR. We can discuss if this is necessary as you may have more customization needs that you don't want to upstream.

Issue

Closes #5015

Documentation

Added.

cc @derhuerst @hbruch

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.15 🎉

Comparison is base (53cecaa) 64.16% compared to head (c3b7d99) 64.32%.

Additional details and impacted files

@@              Coverage Diff              @@
##             dev-2.x    #5023      +/-   ##
=============================================
+ Coverage      64.16%   64.32%   +0.15%     
- Complexity     13723    13803      +80     
=============================================
  Files           1687     1689       +2     
  Lines          66741    66771      +30     
  Branches        7188     7189       +1     
=============================================
+ Hits           42826    42949     +123     
+ Misses         21516    21417      -99     
- Partials        2399     2405       +6     

see 63 files with indirect coverage changes

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[derhuerst]

"@timestamp": "2023-04-03T13:28:08.058026697+02:00"

Note that according to Wikipedia ISO 8601 specifies no maximum number of fractional digits, some widely used implementations limit the number of fractions:

• PostgreSQL only accepts 6 digits
• Microsoft SQL Servers datetime2() seems to accept 7 digits, while its older datetime() seems to only accept 3

I'm not sure if these limitations are worth reducing the precision of OTP's logs. On the other hand, the 9th fractional digit has limited value anyways.

[leonardehrenfried]

You're right in that nobody needs that ridiculous level of precision however, there is value in just using the default configuration (which this is) and not fiddle it.

[vpaturet]

It is probably not necessary to add the Entur configuration, we use already different versions of it, so we need to customize it anyway.
It might be a good example configuration that could be added in Logging.md, though.

[vpaturet]

Tested successfully with the Entur configuration by overriding the embedded logback configuration file with an external configuration file.

[t2gran]

Looks good to me, but I will leave the formal reviews to the assigned reviewers.