More flexible audit logging

[prayerslayer]

Hi there!

I'm not completely happy with the audit logging in friboo. The way it currently works is storing all successful (2xx) responses to PUT/POST/PATCH/DELETE requests, which is very unflexible and low-level.

Sometimes your audit logs involve data that's not in a HTTP body, you may want to ship it somewhere else than S3 (file, database, REST API...) and so forth.

I don't have a good idea yet how to do this in a good and simple way. Maybe one could (mis?)use timbre to have already an ecosystem for appenders available and/or easily plug custom ones?

[prayerslayer]

Okay, played around with timbre° a little. What about this:

• We reuse the exiting audit-log component
• It's a component that gives you a logging function which you just call, preferrably without string message and only clojure data
• We provide some timbre appenders out of the box, amongst others s3 (which will be the existing audit log logic)
• Which one to use (and how, such as which bucket to append into, which function to use for transforming into appropriate output...) you configure via environment
• PROFIT

What do you think? Overkill? Not needed?

There are also some follow-up questions to clarify, e.g. how this relates to friboo.log and slf4j.

° If you have another suggestion, please go ahead. I just find the existing concepts of appenders etc quite flexible and reusable.

[prayerslayer]

• Use timbre appenders for shipping
• Don't use output-fn of timbre
• Existing logging stays as-is
• Appenders can be enabled/disabled with environment variables
• Isolate appenders with ns-whitelist
• Other appenders configured outside of friboo should not log stuff from friboo

Clarify: How SLF4J Markers play in here http://www.slf4j.org/api/org/slf4j/Marker.html

Apparently Markers are not supported in tools.logging or timbre, so it's not as easy to use them.