Collect Cert-Manager Metrics with OpenTelemetry

Overview

cert-manager is a Kubernetes add-on that manages TLS certificate issuance and renewal. It exposes Prometheus metrics on port 9402 across three components: the controller, the webhook, and the cainjector.

Prerequisites

• cert-manager v1.x installed in your Kubernetes cluster with Prometheus metrics enabled
• OpenTelemetry Collector Contrib deployed in-cluster with access to the cert-manager namespace
• An instance of SigNoz (either Cloud or Self-Hosted)

Setup

Install cert-manager in your cluster and configure the OpenTelemetry Collector to scrape cert-manager Prometheus metrics.

Step 1: Install cert-manager with Prometheus metrics enabled

If cert-manager isn't installed, add the Jetstack Helm repository and install it:

helm repo add jetstack https://charts.jetstack.io --force-update

helm install cert-manager jetstack/cert-manager \
  --namespace cert-manager \
  --create-namespace \
  --set crds.enabled=true \
  --set prometheus.enabled=true

prometheus.enabled=true enables /metrics on port 9402 for all three components. This is the default in the Helm chart, but set it explicitly to ensure it hasn't been overridden. If cert-manager is already installed, upgrade with the same flag.

Verify the endpoints are reachable:

kubectl port-forward -n cert-manager svc/cert-manager 9402:9402 &
curl -s http://localhost:9402/metrics | grep certmanager_certificate_ready_status

Step 2: Add the Prometheus scrape config to your OTel Collector

Append this snippet to your existing OTel Collector config, adding prometheus alongside existing receivers:

receivers:
  prometheus:
    config:
      scrape_configs:
        # cert-manager controller
        - job_name: cert-manager
          scrape_interval: 30s
          static_configs:
            - targets:
                - cert-manager.cert-manager.svc.cluster.local:9402

        # cert-manager webhook
        - job_name: cert-manager-webhook
          scrape_interval: 30s
          static_configs:
            - targets:
                - cert-manager-webhook.cert-manager.svc.cluster.local:9402

        # cert-manager cainjector
        - job_name: cert-manager-cainjector
          scrape_interval: 30s
          static_configs:
            - targets:
                - cert-manager-cainjector.cert-manager.svc.cluster.local:9402

The targets use in-cluster DNS. If your OTel Collector runs in a different namespace, adjust the hostnames to match (<service>.<namespace>.svc.cluster.local).

Then enable the prometheus receiver in your metrics pipeline:

service:
  pipelines:
    metrics:
      receivers: [otlp, prometheus] # add prometheus alongside existing receivers
      processors: [batch]
      exporters: [otlp]

Step 3: Configure the exporter

If you don't have an OTLP exporter yet, add this block.

exporters:
  otlp:
    endpoint: 'ingest.<region>.signoz.cloud:443'
    tls:
      insecure: false
    headers:
      'signoz-ingestion-key': '<your-ingestion-key>'

Verify these values:

• <region>: Your SigNoz Cloud region.
• <your-ingestion-key>: Your SigNoz ingestion key.

Step 4: Restart the OTel Collector

Apply the updated config and restart the collector:

# Kubernetes Helm example — replace <collector-namespace> with your OTel Collector namespace
helm upgrade otel-collector open-telemetry/opentelemetry-collector \
  --namespace <collector-namespace> \
  -f otel-collector-values.yaml

Or restart the pod directly if the config is mounted via a ConfigMap:

kubectl rollout restart deployment -n <collector-namespace> otel-collector

Validate

After restarting the collector, go to SigNoz → Metrics Explorer and search for certmanager_.

Metrics appear within ~60 seconds:

Next steps

• Cert-Manager Dashboard: import the pre-built SigNoz dashboard for certificate and controller visibility
• Metric-based alerts: set up alerts for certificate expiry or issuer failures

Get Help

If you need help with the steps in this topic, please reach out to us on SigNoz Community Slack.

If you are a SigNoz Cloud user, please use in product chat support located at the bottom right corner of your SigNoz instance or contact us at cloud-support@signoz.io.