Regexp for an slf4j log format

Opening this as an issue to get your opinion. I was fairly confident the PR would be rejected since the format depends on the slf4 log formatter people use. But I added a regexp for a fairly used slf4j log format:

log line:

11:22:19.068 [Something Something #1] INFO  a.b.c.d.e.f.gh.KLMNO - Some words that make sense and numbers 10.2.32.84

regex:

Message pattern: ^([^\[]+)\s*(\[.*])\s*([A-Z]+)\s*\s*(\S*)\s*-(.+)$
Message start pattern: ^\d
Time format: HH:mm:ss.SSS
Time capture group: 1
Severity capture group: 3
Category capture group: 4

feel free to test it at https://regex101.com

[rala72]

I’ve found another solution for my Spring logs. It works for example for this one:

2019-05-06 15:06:19.038 DEBUG 1484 --- [main] a.a.t.s.g.backend.BackendApplication     : Running with Spring Boot v2.1.2.RELEASE, Spring v5.1.4.RELEASE

my config:

message pattern: ^([^ ]* [^ ]*)\s*([^ ]*)\s*(\d*)\s*-*\s*(\[[^]]*\])\s*([^ ]*)\s*:\s*(.*)$
message start pattern: ^\d
timeformat: yyyy-MM-dd HH:mm:ss.SSS
time capture group: 1
severity capture group: 3
category capture group: 4

I also made the default patterns for severity case insensitve by adding (?i) at the beginning of all of them and added a debug pattern: (?i)^\s*d(ebug)?\s*$ with a dark blue color. Finally I made the ing of warning optional with this pattern: (?i)^\s*w(arn(ing)?)?\s*$. It works now for messages like the following:

2019-05-06 19:48:16.804  WARN 16156 --- [http-nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.bind.MethodArgumentNotValidException: [...]

[knah]

It’s understandable that people use different log formats. This means that included formats serve more as examples, rather than something deemed universally useful, although including some common log formats is definitely nice.

Regarding your format: there is \s*\s* - probably that can be just one \s*. Additionally, it might be better to use [^\]]* instead of .* for the text in square brackets. Besides, it looks like there are two groups that have category-like functionality - the one in square brackets, and the one with what appears to be class name. Probably we need a more flexible approach for categories, given that there are multiple log format that contain more than one.

As another side note, we probably should include sample log lines with provided formats - trying to decipher the regex to get a feel for what a log format looks like is a bit too bothersome.