Metrics, exporters and scraping

Not running Starting usually ~20 s

Step 7 of 7 · summary · 2 min

Summary

An exporter serves current values as text: a line is a name, labels and a number, and # TYPE says whether it is a counter or a gauge.
Prometheus scrapes the targets in scrape_configs every scrape_interval by itself, adds the job and instance labels and writes up.
The scrape state is in /api/v1/targets: health and the reason in lastError; up = 0 means the target did not answer.
A new job is a block in prometheus.yml, promtool check config and systemctl reload prometheus.
The thousands of lines at the start of the lesson are time series, one per label combination, and the memory free for programs is MemAvailable.

Ubuntu 24.04