Tag resolution

Knative Serving resolves image tags to a digest when you create a Revision. This helps to provide consistency for Deployments. For more information, see the documentation on Why we resolve tags in Knative.

Important

The Knative Serving controller must be configured to access the container registry to use this feature.

Custom certificates

If you are using a registry that has a self-signed certificate, you must configure the default Knative Serving controller Deployment to trust that certificate. You can configure trusting certificates by mounting your certificates into the controller Deployment, and then setting the environment variable appropriately.

Procedure

1. If you are using a custom-certs secret that contains your CA certificates, add the following spec to the default Knative Serving controller Deployment:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: controller
     namespace: knative-serving
   spec:
     template:
       spec:
         containers:
           - name: controller
             volumeMounts:
               - name: custom-certs
                 mountPath: /path/to/custom/certs
             env:
               - name: SSL_CERT_DIR
                 value: /path/to/custom/certs
         volumes:
           - name: custom-certs
             secret:
               secretName: custom-certs
   

   Knative Serving accepts the SSL_CERT_FILE and SSL_CERT_DIR environment variables.

2. Create a secret in the knative-serving namespace that points to your root CA certificate, and then save the current Knative Serving controller Deployment:

   kubectl -n knative-serving create secret generic customca --from-file=ca.crt=/root/ca.crt
   

   kubectl -n knative-serving get deploy/controller -o yaml > knative-serving-controller.yaml
   

Corporate proxy

If you are behind a corporate proxy, you must proxy the tag resolution requests between the controller and your registry.

Knative accepts the HTTP_PROXY and HTTPS_PROXY environment variables, so you can configure the controller Deployment as follows:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: controller
  namespace: knative-serving
spec:
  template:
    spec:
      containers:
        - name: controller
          env:
            - name: HTTP_PROXY
              value: http://proxy.example.com
            - name: HTTPS_PROXY
              value: https://proxy.example.com