Add metrics and related endpoints

[stevespringett]

Add metrics and related endpoints similar to what DropWizard or SpringBoot provides.

• /auditevents - should return the contents of dependency-track-audit.log
• /env - should return all environment variables and Java system properties
• /health - should return various high-level health info
• /logfile - should return the contents of dependency-track.log
• /metrics - should return details metrics to measure system performance

Alpine should contain an AbstractMetricsResource with implementations of the above endpoints. Each application that is built on Alpine would simply extend AbstractMetricsResource so that the app can specify what permissions are necessary for each.

NOTE: It may be possible to simply include Dropwizard Metrics for /health and /metrics capabilities as the module seems to be standalone with minimal dependencies.

[sandeep-chekuri]

Do we have any timelines on when this feature would be available in Alpine and eventually in dependency track?

[stevespringett]

No timeline. It's not currently being worked on or planned. Too much other things in DT being worked on at the moment.

[davidkarlsen]

I can highly recommend micrometer for metrics. It's very nice and versatile. And use prometheus dataformat as standard, as it is the de-facto standard.