MS-12645: add file appender in logback config

[damienlibouton]

The idea is to have the possibility to log the application server in files.

Then we can use the parameter -Dlogging.file.name="/your/path/to/app.log" to expose the logs in a file when starting the fatjar.

[LotuxPunk]

Hey Damien 👋
We do not see any problem of having such a change, just that by default if we do not provide that argument, there will be log created with logging.file.name_IS_UNDEFINED as a file name, would it be possible to adapt this change to disable that logging output if the path isn't provided ?

[damienlibouton]

Hello Clément,

Thank you for your review !

To enable a conditional activation, I need to update the Logback dependency to aversion > 1.5.24 (currently 1.5.18). However, it seems there is a conflict with the Logback version in kmap, or I might be missing something... In short, I'm stuck with this solution !

I also tried activating it using a specific spring profile. To do this, I had to rename the logback.xml to logback-spring.xml to access the spring profile values. However, after renaming the file, for some reason, Logback could no longer find the configuration xml, and I couldn’t figure out why....

My other proposal is to add the Janino dependency to enable the use of if conditions in the xml configuration file.
I've pushed a commit with this proposal, and my local testing seems to work with this solution...

Let me know if this approach is acceptable to you.