docker-exporter

Appearance

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 correctly on both cgroup versions, and idles around 7 MiB of RAM. Metric names are cAdvisor-compatible, so existing Prometheus scrape configs and Grafana dashboards work without a rewrite.

The problem it solves ​

On a Raspberry Pi 5 (ARM64 + cgroup v2), cAdvisor returns zero for container_memory_working_set_bytes, so memory dashboards silently break — part of cAdvisor's broader ARM-side pain (#2523).

This is upstream-acknowledged and unfixed: cAdvisor #3469 was closed "not planned" on 2025-12-09, and it persists even after you enable memory cgroups on the Pi. Read the full cAdvisor ARM64 zero-memory bug story →

cAdvisor's footprint is also large for a single-board computer: 9–17% sustained CPU, ~80–150 MiB RAM per host, privileged mode, and six mounted host paths — because it monitors the whole host, not just Docker (full footprint benchmark →).

What you get ​

  • Correct memory working set 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 either hit the ARM64/cgroup v2 memory bug or want a tiny-footprint 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 ​