[Documentation] Clarification about using locally built images

For feature requests, describe what you’d like to add or change At the present time it’s not clear how to use locally built images (by nerdctl build) in k8s manifests. There is a phrase on main RD site The container images you build can be run by Kubernetes immediately without the need for a registry and no more info about that

To Reproduce

1. build image nerdctl build -t local/my-app:latest .
2. Deploy simple manifest:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: my-app-deployment
     labels:
       app: my-app
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: my-app
     template:
       metadata:
         labels:
           app: my-app
       spec:
         containers:
           - name: my-app
             image: local/my-app:latest
   

   by command:

   kubectl apply -f my-app.yaml
   

3. Get events

   kubectl get events
   

   See error something like this:

   Failed to pull image "local/my-app:latest": rpc error: code = Unknown desc = failed to pull and unpack image "docker.io/local /my-app:latest": failed to resolve reference "docker.io/local/my-app:latest": pull access denied, repository does not exist or may require authorization: server message: insufficient_scope: authorization failed
   

Setup (please complete the following information):

• OS: MacOS Monterey
• Rancher Desktop version: 0.6.1
• Kubernetes version: 1.21.6

[taylorza]

In addition to creating the image in the k8s.io namespace you should also set the imagePullPolicy to Never

[AkihiroSuda]

Please provide definitive steps to use locally built images with nerdctl in K8s manifests.

# nerdctl --namespace k8s.io build -t foo /some-dockerfile-directory
# kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: foo
spec:
  containers:
    - name: foo
      image: foo
      imagePullPolicy: Never
EOF