How to recover a docker image from Kubernetes Node

When you’ve lost a Docker image from your remote repository but it’s still cached on a Kubernetes Node, you can recover it using containerd’s command-line tool, ctr. This tool is typically bundled with containerd installations.

Using ctr

ctr, often included in containerd installations, can be used in conjunction with crictl, a standalone kubernetes-sigs project. Here’s how to interact with ctr and containerd:

1. Set up the environment: To interact with ctr define this environment variable:

   export CONTAINER_RUNTIME_ENDPOINT="unix:///run/containerd/containerd.sock"

2. For basic authentication (e.g., with AWS ECR):

    ECR_REGION=us-east-1
    ECR_PASSWORD=$(aws ecr get-login-password --region $ECR_REGION)
   

3. Tagging and pushing images:

    ctr -n k8s.io image tag <IMAGE> <ECR:IMAGE:TAG>
    ctr -n k8s.io image push --user "AWS:$ECR_PASSWORD" <ECR:IMAGE:TAG>
   

   Note: The ‘k8s.io’ namespace is required for image interactions.

Other Helpful Tools

• nerdctrl: Docker-compatible CLI for containerd
• crictl: crictl provides a CLI for CRI-compatible container runtimes.

Your donations are appreciated. Thank you!