Kubernetes Ingress TLS Configuration Guide

The port was open, the service ready, but the connection still refused. The problem was clear: TLS configuration on the Ingress was wrong.

Ingress resources in Kubernetes control how external traffic reaches your cluster. They route HTTP and HTTPS requests to the correct backend service. When TLS is configured correctly, your Ingress can terminate HTTPS at the edge and keep traffic encrypted end-to-end. When it’s wrong, you face broken handshakes, insecure endpoints, or opaque errors that stall deployment.

To set up TLS on an Ingress resource, you define a TLS block in your manifest. This block includes the domain names and the name of the Kubernetes Secret holding your certificate and private key. The Secret must use the type kubernetes.io/tls and contain tls.crt and tls.key.

Example:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
 name: example-ingress
spec:
 tls:
 - hosts:
 - app.example.com
 secretName: example-tls
 rules:
 - host: app.example.com
 http:
 paths:
 - path: /
 pathType: Prefix
 backend:
 service:
 name: example-service
 port:
 number: 443

This configuration tells the Ingress controller to present the certificate from example-tls when handling HTTPS requests to app.example.com.

Common pitfalls include mismatched host names between your TLS block and the certificate’s Common Name or Subject Alternative Names, using an unsupported secret type, forgetting to enable HTTPS on your backend service, or omitting the TLS port from service definitions. Always check the controller logs; most will print explicit TLS errors for fast debugging.

Advanced setups may leverage cert-manager to automatically obtain and renew TLS certificates from Let’s Encrypt. In that case, cert-manager will manage the Secret resources, and your Ingress manifests only need correct tls entries and annotations for certificate issuance.

Ingress TLS configuration is not optional in modern deployments. Browsers and APIs demand HTTPS by default, and properly setting it up in Kubernetes is the quickest way to meet that requirement without rewriting applications. Audit your manifests, validate certificate details, and confirm that your Ingress controller supports the desired TLS features, including HTTP/2 and modern cipher suites.

Set it up right, and traffic flows securely from the internet to your workloads. Skip details, and your edge becomes a point of failure.

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