checkId: check.telemetry.otlp.endpoint plugin: stellaops.doctor.observability severity: warn tags: [observability, telemetry, otlp, air-gap]

OTLP Endpoint

What It Checks

Verifies that the OTLP (OpenTelemetry Protocol) collector endpoint is reachable. The check:

• Reads the endpoint from Telemetry:OtlpEndpoint configuration.
• Sends a GET request to {endpoint}/v1/health with a 5-second timeout.
• Passes if the endpoint returns a successful HTTP response.
• Warns on non-success status codes, timeouts, or connection failures.

The check only runs when Telemetry:OtlpEndpoint is configured.

Air-Gap Behavior

When the deployment is sealed by AirGap policy, or STELLAOPS_DOCTOR_OFFLINE_PROFILE=true forces Doctor offline mode, external OTLP collector endpoints return Skip with airGapSealed=true. Loopback, link-local, RFC1918, and unique-local IPv6 collectors are still probed because observability collectors are commonly internal to sealed deployments.

If your sealed network uses a routable non-private address for an internal collector, Doctor cannot resolve policy intent through DNS without creating another probe. Prefer an RFC1918, loopback, link-local, or unique-local endpoint for this check.

Why It Matters

OTLP is the standard protocol for exporting traces, metrics, and logs to observability backends (Grafana, Jaeger, Datadog, etc.). If the collector is unreachable, telemetry data is lost, making it impossible to monitor service performance, trace request flows, or detect anomalies.

Common Causes

• OTLP collector not running
• Wrong endpoint configured
• Network connectivity issue or firewall blocking connection
• Collector health endpoint not available at /v1/health

How to Fix

Docker Compose

environment:
  Telemetry__OtlpEndpoint: "http://otel-collector:4317"

# Check if collector is running
docker ps | grep otel

# Check collector logs
docker logs otel-collector --tail 50

# Test connectivity
docker exec <platform-container> curl -v http://otel-collector:4317/v1/health

Bare Metal / systemd

# Check collector status
systemctl status otel-collector

# Test endpoint
curl -v http://localhost:4317/v1/health

# Check port binding
netstat -an | grep 4317

Edit appsettings.json:

{
  "Telemetry": {
    "OtlpEndpoint": "http://localhost:4317"
  }
}

Kubernetes / Helm

telemetry:
  otlpEndpoint: "http://otel-collector.monitoring.svc:4317"

kubectl get pods -n monitoring | grep otel
kubectl logs -n monitoring <otel-collector-pod> --tail 50

Verification

stella doctor run --check check.telemetry.otlp.endpoint

Related Checks

• check.metrics.prometheus.scrape — verifies Prometheus metrics endpoint accessibility
• check.logs.directory.writable — verifies log directory is writable