## What
Add an optional Prometheus `/metrics` HTTP endpoint to `act_runner` so operators can observe runner health, polling behavior, job outcomes, and RPC latency without scraping logs.
New surface:
- `internal/pkg/metrics/metrics.go` — metric definitions, custom `Registry`, static Go/process collectors, label constants, `ResultToStatusLabel` helper.
- `internal/pkg/metrics/server.go` — hardened `http.Server` serving `/metrics` and `/healthz` with Slowloris-safe timeouts (`ReadHeaderTimeout` 5s, `ReadTimeout`/`WriteTimeout` 10s, `IdleTimeout` 60s) and a 5s graceful shutdown.
- `daemon.go` wires it up behind `cfg.Metrics.Enabled` (disabled by default).
- `poller.go` / `reporter.go` / `runner.go` instrument their existing hot paths with counters/histograms/gauges — no behavior change.
Metrics exported (namespace `act_runner_`):
| Subsystem | Metric | Type | Labels |
|---|---|---|---|
| — | `info` | Gauge | `version`, `name` |
| — | `capacity`, `uptime_seconds` | Gauge | — |
| `poll` | `fetch_total`, `client_errors_total` | Counter | `result` / `method` |
| `poll` | `fetch_duration_seconds`, `backoff_seconds` | Histogram / Gauge | — |
| `job` | `total` | Counter | `status` |
| `job` | `duration_seconds`, `running`, `capacity_utilization_ratio` | Histogram / GaugeFunc | — |
| `report` | `log_total`, `state_total` | Counter | `result` |
| `report` | `log_duration_seconds`, `state_duration_seconds` | Histogram | — |
| `report` | `log_buffer_rows` | Gauge | — |
| — | `go_*`, `process_*` | standard collectors | — |
All label values are predefined constants — **no high-cardinality labels** (no task IDs, repo URLs, branches, tokens, or secrets) so scraping is safe and bounded.
## Why
Teams self-hosting Gitea + `act_runner` at scale need to answer basic SRE questions that are currently invisible:
- How often are RPCs failing? Which RPC? (`act_runner_client_errors_total`)
- Are runners saturated? (`act_runner_job_capacity_utilization_ratio`, `act_runner_job_running`)
- How long do jobs take? (`act_runner_job_duration_seconds`)
- Is polling backing off? (`act_runner_poll_backoff_seconds`, `act_runner_poll_fetch_total{result=\"error\"}`)
- Are log/state reports slow? (`act_runner_report_{log,state}_duration_seconds`)
- Is the log buffer draining? (`act_runner_report_log_buffer_rows`)
Today operators have to grep logs. This PR makes all of the above first-class metrics so they can feed dashboards and alerts (`rate(act_runner_client_errors_total[5m]) > 0.1`, capacity saturation alerts, etc.).
The endpoint is **disabled by default** and binds to `127.0.0.1:9101` when enabled, so it's opt-in and safe for existing deployments.
## How
### Config
```yaml
metrics:
enabled: false # opt-in
addr: 127.0.0.1:9101 # change to 0.0.0.0:9101 only behind a reverse proxy
```
`config.example.yaml` documents both fields plus a security note about binding externally without auth.
### Wiring
1. `daemon.go` calls `metrics.Init()` (guarded by `sync.Once`), sets `act_runner_info`, `act_runner_capacity`, registers uptime + running-jobs GaugeFuncs, then starts the server goroutine with the daemon context — it shuts down cleanly on `ctx.Done()`.
2. `poller.fetchTask` observes RPC latency / result / error counters. `DeadlineExceeded` (long-poll idle) is treated as an empty result and **not** observed into the histogram so the 5s timeout doesn't swamp the buckets.
3. `poller.pollOnce` reports `poll_backoff_seconds` using the pre-jitter base interval (the true backoff level), and only when it changes — prevents noisy no-op gauge updates at the `FetchIntervalMax` plateau.
4. `reporter.ReportLog` / `ReportState` record duration histograms and success/error counters; `log_buffer_rows` is updated only when the value changes, guarded by the already-held `clientM`.
5. `runner.Run` observes `job_duration_seconds` and increments `job_total` by outcome via `metrics.ResultToStatusLabel`.
### Safety / security review
- All timeouts set; Slowloris-safe.
- Custom `prometheus.NewRegistry()` — no global registration side-effects.
- No sensitive data in labels (reviewed every instrumentation site).
- Single new dependency: `github.com/prometheus/client_golang v1.23.2`.
- Endpoint is unauthenticated by design and documented as such; default localhost bind mitigates exposure. Operators exposing externally should front it with a reverse proxy.
## Verification
### Unit tests
\`\`\`bash
go build ./...
go vet ./...
go test ./...
\`\`\`
### Manual smoke test
1. Enable metrics in `config.yaml`:
\`\`\`yaml
metrics:
enabled: true
addr: 127.0.0.1:9101
\`\`\`
2. Start the runner against a Gitea instance: \`./act_runner daemon\`.
3. Scrape the endpoint:
\`\`\`bash
curl -s http://127.0.0.1:9101/metrics | grep '^act_runner_'
curl -s http://127.0.0.1:9101/healthz # → ok
\`\`\`
4. Confirm the static series appear immediately: \`act_runner_info\`, \`act_runner_capacity\`, \`act_runner_uptime_seconds\`, \`act_runner_job_running\`, \`act_runner_job_capacity_utilization_ratio\`.
5. Trigger a workflow and confirm counters increment: \`act_runner_poll_fetch_total{result=\"task\"}\`, \`act_runner_job_total{status=\"success\"}\`, \`act_runner_report_log_total{result=\"success\"}\`.
6. Leave the runner idle and confirm \`act_runner_poll_backoff_seconds\` settles (and does **not** churn on every poll).
7. Ctrl-C and confirm a clean \"metrics server shutdown\" log line (no port-in-use error on restart within 5s).
### Prometheus integration
Add to \`prometheus.yml\`:
\`\`\`yaml
scrape_configs:
- job_name: act_runner
static_configs:
- targets: ['127.0.0.1:9101']
\`\`\`
Sample alert to try:
\`\`\`
sum(rate(act_runner_client_errors_total[5m])) by (method) > 0.1
\`\`\`
## Out of scope (follow-ups)
- TLS and auth on the metrics endpoint (mitigated today by localhost default; add when operators need external scraping).
- Per-task labels (intentionally avoided for cardinality safety).
---
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/820
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Co-committed-by: Bo-Yi Wu <appleboy.tw@gmail.com>
- Removed `deadcode`, `structcheck`, and `varcheck` linters from `.golangci.yml`
- Fixed a typo in a comment in `daemon.go`
- Renamed `defaultActionsUrl` to `defaultActionsURL` in `exec.go`
- Removed unnecessary else clause in `exec.go` and `runner.go`
- Simplified variable initialization in `exec.go`
- Changed function name from `getHttpClient` to `getHTTPClient` in `http.go`
- Removed unnecessary else clause in `labels_test.go`
Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/289
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Co-committed-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Follow #242, #244Fixes#258
Users could use `docker_host` configuration to specify which docker daemon will be used by act_runner.
- If `docker_host` is **empty**, act_runner will find an available docker host automatically.
- If `docker_host` is **"-"**, act_runner will find an available docker host automatically, but the docker host won't be mounted to the job containers and service containers.
- If `docker_host` is **not empty or "-"**, the specified docker host will be used. An error will be returned if it doesn't work.
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/260
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-committed-by: Zettat123 <zettat123@gmail.com>
- Import "path", "runtime", "strconv", and "strings" packages in daemon.go
- Move "Starting runner daemon" log message to a different location
- Refactor log formatter initialization and add debug level caller information
- Split Config struct into separate Log, Runner, Cache, and Container structs with comments in config.go
Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/225
Reviewed-by: Jason Song <i@wolfogre.com>
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Co-committed-by: Bo-Yi Wu <appleboy.tw@gmail.com>
