Set up a prometheus endpoint for collecting metrics

[fricklerhandwerk]

Collect data about the system in order to measure resource consumption and inform actions to keep it sustainable:

• number of CVEs
• number of derivations
• number of evaluations
• evaluation latency (how long does it take to evaluate a channel)
• number of GitHub events processed
• number of issues
• disk space consumption per table
• query latencies
• response times for every view