TLS certificates are automatically renewed before expiry

An expired TLS certificate produces browser warnings that users train themselves to click through — or it breaks service entirely, causing an outage with no security justification. Manual certificate rotation fails at scale: teams forget expiry dates, renewal windows get missed during vacations, and a 90-day Let's Encrypt cert can silently expire over a long weekend. NIST 800-53 SC-17 requires certificate management controls. CWE-295 covers improper certificate validation. Automated renewal removes human failure from a process that must succeed on a strict calendar.

Deploy cert-manager in your cluster and annotate Ingress resources for automatic renewal. Install cert-manager, then configure a ClusterIssuer and annotate your Ingress in k8s/ingress.yaml:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
spec:
  tls:
    - hosts:
        - example.com
      secretName: example-tls
  rules:
    - host: example.com
      # ...

cert-manager renews certificates 30 days before expiry automatically. For cloud-managed load balancers, use ACM (AWS) or managed certificates (GKE) to delegate renewal entirely to the provider.

• ID: infrastructure-hardening.network-tls.cert-auto-renewal

• Severity: high

• What to look for: Count all TLS certificate references across Ingress manifests, Certificate resources, and cloud provider configurations. For each certificate, determine whether it is managed by an automated renewal system (cert-manager, ACM, Cloud Armor) or is manually provisioned. List all certificate sources found.

• Pass criteria: 100% of TLS certificates used by the project are automatically renewed before expiry via cert-manager, a cloud provider service (ACM, Cloud Armor), or equivalent automation. No manually managed certificates exist in production. Report the count: "X certificates found, all Y managed by automated renewal."

• Fail criteria: Any certificate is self-signed or statically provided with no renewal mechanism, or expiry dates require manual rotation.

• Skip (N/A) when: The project is in development-only or staging without production TLS.

• Detail on fail: Quote the certificate reference. Example: "Kubernetes Ingress references TLS secret 'tls-secret' with no cert-manager annotation. Certificate has no renewal mechanism." or "Manual SSL certificate in use with no automation for renewal"

• Remediation: Use cert-manager with Let's Encrypt for automatic renewal:

  apiVersion: cert-manager.io/v1
  kind: Certificate
  metadata:
    name: app-cert
  spec:
    secretName: tls-secret
    issuerRef:
      name: letsencrypt-prod
    commonName: example.com
    dnsNames:
      - example.com
      - www.example.com
  

  Or annotate your Ingress directly:

  metadata:
    annotations:
      cert-manager.io/cluster-issuer: "letsencrypt-prod"
  spec:
    tls:
      - hosts:
          - example.com
        secretName: tls-secret