When to use this approach

Need to start a container right now, but the image isn’t in a registry yet? This approach is for you. We’re going to export your image as a tar file and import it into Kubernetes’ containerd

⚠️ Limitations

Consider this a temporary measure while you arrange a registry because:

• Pods will fail if the image is not loaded on the node!
• Any changes to the image require you to update it on all nodes.
• New nodes in the cluster also need the image to be imported.

Export image

Make sure you have the image available as a tar file. Here’s how to save one from a machine with Docker:

docker save repository/image --output ./image.tar

Transfer and import on each node

Copy the tar file to each node with a command like:

scp image.tar node:/tmp/

Run this command on each node to load the image into containerd:

sudo ctr -n k8s.io images import image.tar

Verify import succeeded with:

sudo ctr -n k8s.io images ls

Deploy with correct pull policy

To use this image in a Kubernetes deployment, make sure it’s set to imagePullPolicy: Never

Here’s an example deployment:

kind: Deployment
apiVersion: apps/v1
metadata:
  name: my-app
  labels:
    app: my-app

spec:
  replicas: 1
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-app
          image: xxxxx/my-app
          imagePullPolicy: Never