use logstash-logback-encoder (JSON logging)

[hohwille]

For logging eiPaaS is using ELK and today I learned that they have standardized the log-format and require apps to follow this. This technically means they use this standard OSS encoder for logback which produces JSON log lines instead of regular text patterns:
https://github.com/logstash/logstash-logback-encoder
@amarinso stated:

I would vote for having a single log file, json formatted and tools (or tips or techniques ) to split it if required or filter/prettyprint. We should be pushing for systems where log aggregators are the new normal. Let's make modern techniques, principles and patterns our default blueprint.

@maihacke stated:

I totally agree. Having a central log-collection is normal today and e.g. a security requirement in German public sector projects. So we should go with the JSON-Format per default.
I do so and have a special log-config for development where it is deactivated.

[amarinso]

We should test if the JSON output formatting adds any noticeable performance penalty for an app, so in that case we can even go for async appenders. I read out of curiosity that in logstash they are using LMAX disruptor for enqueing the messages... nice!

[hohwille]

merged PR #36 hence done.

[hohwille]

We should test if the JSON output formatting adds any noticeable performance penalty for an app, so in that case we can even go for async appenders. I read out of curiosity that in logstash they are using LMAX disruptor for enqueing the messages... nice!

I do not see a real issue with the log messages we are producing. In production regular mode will most probably even to raise the loglevel to INFO.
However, your knowledge/observation about async appenders sounds very interesting. Please feel invited to add a link or some example config to the documentation:
https://github.com/devonfw-wiki/devon4j/wiki/guide-logging