docker-exporter

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docker-exporter for ARM64 & Raspberry Pi 5 ​

docker-exporter is a Prometheus exporter for Docker container metrics, written in Rust and built for ARM64 homelabs running cgroup v2.

It reads the Docker stats API directly, computes the memory working set the way docker stats does on both cgroup versions, and idles around 7 MiB of RAM. Metric names are cAdvisor-compatible, so existing Prometheus scrape configs and most Grafana dashboards work without a rewrite.

The problem it solves ​

cAdvisor monitors the whole host, which is a lot of machinery for a single-board computer. It runs privileged with five host mounts and keeps walking the cgroup tree on a timer, whether anyone scrapes it or not. On a quiet Raspberry Pi 5 it used 0.87 to 1.72% of a core and 22.5 to 35.6 MiB, depending on its housekeeping interval, against docker-exporter's 0.13% and 4.2 MiB. On a busy Rock 5B+ with 37 containers it used 10.5 to 20.4% and 128 to 429 MiB, against docker-exporter's 0.67% and 5.1 MiB, for the same numbers (full footprint benchmark →).

Memory reads zero on a Raspberry Pi?

That's the Pi's boot configuration, not a bug in any exporter. The memory cgroup is disabled at boot, so docker stats, cAdvisor and docker-exporter all read zero until you add cgroup_enable=memory. How to fix it →

What you get ​

  • Memory working set as docker stats computes it, on cgroup v1 and v2 (usage − inactive_file on v2, usage − cache on v1).
  • Per-container CPU, memory, network, and block I/O, plus state, health, and lifecycle metrics.
  • A read-only Docker socket and non-root execution (UID 65532, no privileged mode).
  • On-demand collection — no background polling; each scrape fetches stats with a 5 s per-container timeout.
  • Glob-aware container exclusion via EXCLUDE_CONTAINERS.
  • /health and /ready endpoints (the image's HEALTHCHECK is already wired).

When to use it ​

docker-exporter is purpose-built for one job: per-container Docker metrics. cAdvisor monitors much more (host, processes, OOM events, hardware counters).

  • Use docker-exporter if you already run Prometheus + Grafana and want a small-footprint, unprivileged cAdvisor alternative on an SBC.
  • Keep cAdvisor if you need host/process metrics and its footprint isn't a problem.

See the full docker-exporter vs cAdvisor comparison →.

Next steps ​