Securing a mapped service using a TLS certificate - Knative Serving | Serverless

Securing a service with a custom domain by using a TLS certificate

After you have configured a custom domain for a Knative service, you can use a TLS certificate to secure the mapped service. To do this, you must create a Kubernetes TLS secret, and then update the DomainMapping CR to use the TLS secret that you have created.

If you use net-istio for Ingress and enable mTLS via SMCP using security.dataPlane.mtls: true, Service Mesh deploys DestinationRules for the *.local host, which does not allow DomainMapping for OpenShift Serverless.

To work around this issue, enable mTLS by deploying PeerAuthentication instead of using security.dataPlane.mtls: true.

Prerequisites

You configured a custom domain for a Knative service and have a working DomainMapping CR.
You have a TLS certificate from your Certificate Authority provider or a self-signed certificate.
You have obtained the cert and key files from your Certificate Authority provider, or a self-signed certificate.
Install the OpenShift CLI (oc).

Procedure

Create a Kubernetes TLS secret:

$ oc create secret tls <tls_secret_name> --cert=<path_to_certificate_file> --key=<path_to_key_file>

If you are using Red Hat OpenShift Service Mesh as the ingress for your OpenShift Serverless installation, label the Kubernetes TLS secret with the following:
```
“networking.internal.knative.dev/certificate-uid": “<value>”
```
If you are using a third-party secret provider such as cert-manager, you can configure your secret manager to label the Kubernetes TLS secret automatically. Cert-manager users can use the secret template offered to automatically generate secrets with the correct label. In this case, secret filtering is done based on the key only, but this value can carry useful information such as the certificate ID that the secret contains.

The cert-manager Operator for Red Hat OpenShift is a Technology Preview feature. For more information, see the Installing the cert-manager Operator for Red Hat OpenShift documentation.

Update the DomainMapping CR to use the TLS secret that you have created:

apiVersion: serving.knative.dev/v1alpha1
kind: DomainMapping
metadata:
  name: <domain_name>
  namespace: <namespace>
spec:
  ref:
    name: <service_name>
    kind: Service
    apiVersion: serving.knative.dev/v1
# TLS block specifies the secret to be used
  tls:
    secretName: <tls_secret_name>

Verification

Verify that the DomainMapping CR status is True, and that the URL column of the output shows the mapped domain with the scheme https:

$ oc get domainmapping <domain_name>

Example output

NAME                      URL                               READY   REASON
example.com               https://example.com               True

Optional: If the service is exposed publicly, verify that it is available by running the following command:
```
$ curl https://<domain_name>
```
If the certificate is self-signed, skip verification by adding the -k flag to the curl command.