---
checkId: check.observability.metrics
plugin: stellaops.doctor.observability
severity: warn
tags: [observability, metrics, prometheus]
---
# Metrics Collection

## What It Checks
Inspects `Metrics:*`, `Prometheus:*`, and `OpenTelemetry:Metrics:*` settings. When a metrics port is configured and an `IHttpClientFactory` is available, the check probes `http://localhost:<port><path>`.

The check returns info when metrics are disabled or absent, and warns when the configured endpoint cannot be reached.

## Why It Matters
Metrics are the primary input for alerting, SLO tracking, and capacity planning. Missing or unreachable endpoints remove the fastest signal operators have.

## Common Causes
- Metrics were never enabled in the deployment configuration
- The metrics path or port does not match the listener exposed by the service
- A sidecar or reverse proxy blocks local probing

## How to Fix

### Docker Compose
```yaml
services:
  doctor-web:
    environment:
      Metrics__Enabled: "true"
      Metrics__Path: /metrics
      Metrics__Port: 8080
```

Probe the endpoint from inside the container:

```bash
docker compose -f devops/compose/docker-compose.stella-ops.yml exec doctor-web curl -fsS http://localhost:8080/metrics
```

### Bare Metal / systemd
Bind the metrics port explicitly if the service does not share the main HTTP listener.

### Kubernetes / Helm
Align the `ServiceMonitor` or Prometheus scrape config with the same path and port the app exposes.

## Verification
```bash
stella doctor --check check.observability.metrics
```

## Related Checks
- `check.observability.otel` - OpenTelemetry metrics often share the same collector path
- `check.observability.alerting` - metrics are usually the source for alert rules