docker-exporter

A tiny Prometheus exporter for Docker container metrics, written in Rust for ARM64 homelabs running cgroup v2 — and the fix for cAdvisor's zero-memory bug on Raspberry Pi 5.

📖 Full documentation: docker-exporter.tech

cAdvisor reports zero for container_memory_working_set_bytes on Raspberry Pi 5 (ARM64 + cgroup v2) — a known, upstream-unfixed bug. docker-exporter reads the Docker stats API directly, computes the working set correctly on both cgroup versions, talks to the socket read-only, runs non-root, and idles around 7 MiB of RAM. Metric names are cAdvisor-compatible, so existing Grafana dashboards work unchanged.

Quick start

docker run -d \
  --name docker-exporter \
  -v /var/run/docker.sock:/var/run/docker.sock:ro \
  -p 9713:9713 \
  --restart unless-stopped \
  ghcr.io/dlepaux/docker-exporter:latest

Then scrape http://localhost:9713/metrics. Image is published for linux/amd64 and linux/arm64.

Why docker-exporter

• Correct memory working set on cgroup v1 and v2 (usage − inactive_file on v2, usage − cache on v1) — the number cAdvisor zeroes on ARM64.
• ~9 MB image, ~7 MiB RAM, < 1% CPU — a single static binary on distroless.
• Read-only Docker socket, non-root (UID 65532), no privileged mode.
• On-demand collection — no background loop; 5 s per-container timeout.
• Per-container CPU, memory, network, block I/O, state, health, and lifecycle metrics.
• Glob-aware container exclusion via EXCLUDE_CONTAINERS.

Documentation

Everything lives at docker-exporter.tech:

• Installation · Configuration · Metrics reference
• Prometheus & Grafana · Architecture · Troubleshooting
• Why cAdvisor breaks on Raspberry Pi 5 · docker-exporter vs cAdvisor

Development

cargo build           # debug build
cargo test            # unit + integration tests (some need a local Docker daemon)
cargo clippy          # lints
cargo fmt             # format (CI enforces `cargo fmt --check`)
cargo build --release # release binary

Tests that need a Docker daemon skip themselves when the socket isn't reachable, so cargo test is safe to run anywhere.

Security

Found a vulnerability? Follow the disclosure policy in SECURITY.md — please do not open a public issue.

License

MIT