oy-scrape-jitter

README

oy-scrape-jitter

oy-scrape-jitter queries a Prometheus server to see how regular scrapes are. Perfect scrape alignment happens when the distance between all the scrapes are exactly the same. It enables Prometheus delta-of-delta encoding to reduce significantly the size of the blocks.

Example usage

$ ./oy-scrape-jitter --prometheus.url=https://prometheus.demo.do.prometheus.io/ --log.results-only
ts=2022-04-26T12:11:34.659Z caller=main.go:117 level=info msg="overall results" aligned_targets=0 unaligned_targets=10 max_ms=25

This means that the maximum deviation seen in your scrape jobs is 25ms. You could set --scrape.timestamp-tolerance=25ms to reduce your disk usage over time, by enabling Prometheus to correct timestamps up to 25ms.

Prometheus limits

Prometheus will only apply timestamp tolerance up to 1%. If your scrape interval is 30s, you can only adjust timestamps up to 300ms. Setting a 500ms tolerance will have no effects on jobs with a scrape interval lower than 500s, even if the deviation is tiny.

Plotting the output

By using --plot.file=scrape.png, you can generate a PNG file which shows the scrape timestamps jitter with an histogram.