소개

• Metric collecting 

  • Push
    • Coupling metric backend system
    •  require (agent | login) per application
  • Pull
    
    • require service discovery
    • easy to update setting

• Prometheus

  • Features

    • multi-dimensional data model
    • PromQL
    • no reliance on distributed storage
    • via pull method over HTTP
    • pushing time series is support (gateway)
    • targets r discovered via service discovery or static conf

metric types

• Counter

  • cumulative metric (reset 0)
  • ex)
    • total req
    • total send/receive bytes
    • uptime

• Gauge

  • single numerical value (up & down)
  • ex)
    • cpu / memory usage
    • temperature
    • concurrent req
    • thread cnt

• Histogram

  • samples observations (샘플링을 관찰)
  • ex)
    • <basename>_bucket{le="<upper inclusive bound>"}
      • SLO to serve 95% of req within 300ms
        • http_request_duration_seconds_bucket{le="0.3"}
    • <basename>_sum
    • <basename>_count

• Summary

  • samples observations

  • ex)
    • <basename>{quantile="<Ψ>"}
    • <basename>_sum
    • <basename>_count