Prometheus Scrape and Metrics

Scrape

Relabel

• [Prometheus] Service Discovery & Relabel@小信豬的原始部落

Metrics

Counter

A counter starts at 0, and is incremented. At each scrape Prometheus takes a sample of this state.

what happens when the process restarts and the counter is reset to 0?
rate() will automatically handle this. Any time a counter appears to decrease it’ll be treated as though there was a reset to 0 right after the first data point.

Query

• rate()
  • returns per second values,
  • rate(counter[5s]) is (v5 - v1) / (t5 - t1)
• increase()
  • returns the total across the time period.
  • increase(counter[5s]) is exactly rate(counter[5s]) * 5
• irate()
  • only looks at the last two samples
  • useful for high precision graphs over short time frames.
  • irate(counter[5s]) is (v5 - v4) / (t5 - t4)
• offset
  • counter - counter offest 5s
  • it can’t handle reset situation
• resets()
  • how often the counter resets
  • useful for debugging.

Reference

• How does a Prometheus Counter work?@Robust Perception
• Do I understand Prometheus’s rate vs increase functions correctly?@stackoverflow

Useful Query Example

• https://github.com/infinityworks/prometheus-example-queries/blob/master/README.md