Transfer Container Images

Rancher Desktop provides dockerd and containerd as container engine options to manage containers. There are occasions when you might want to transfer the images from one container engine environment to the other. Or you may have migrated to Rancher Desktop from a different container management application and might want to bring the local images from the previous application environment to the Rancher Desktop environment. This guide provides steps to transfer images using the save and load commands.

Steps

1. Save image(s) from the source environment to a tar archive.

  • nerdctl

  • docker

  • Save a single image

  1. nerdctl save -o local-image.tar image:tag
  • Save multiple images
  1. nerdctl save -o local-images.tar image1:tag1 image2:tag2
  • Save all images in a namespace

Below two commands use jq for JSON parsing. The long command performs the below steps:

  • The nerdctl -n k8s.io image ls sub command gets the list of all images present in the k8s.io namespace, hence doesn’t include images from any other namespace, default for instance.
  • The jq sub command filters and formats the images list from the previous step.
    • The select(.Repository!=\"<none>\") part of the command skips those images with repository having a value of <none>.
    • The if (.Tag=="<none>") then .Repository else (.Repository+":"+.Tag) end') part of the command formats the name of the images to be just the <Repository> or <Repository>:<Tag> depending on whether a image tag has a value of <none> or not.

  • Finally the nerdctl -n k8s.io save -o all-local-images-in-namespace.tar part of the command saves the filtered and formatted images list from the previous two steps into a tar file.

  • Bash

  • PowerShell
  1. nerdctl -n k8s.io save -o all-local-images-in-namespace.tar $(nerdctl -n k8s.io image ls --format '{{json .}}' | jq -r 'select(.Repository!="<none>") | if (.Tag=="<none>") then .Repository else (.Repository+":"+.Tag) end')
  1. nerdctl -n k8s.io save -o all-local-images-in-namespace.tar $(nerdctl -n k8s.io image ls --format '{{json .}}' | jq -r 'select(.Repository!=\"<none>\") | if (.Tag==\"<none>\") then .Repository else (.Repository+\":\"+.Tag) end')
  • Save a single image
  1. docker save -o local-image.tar image:tag
  • Save multiple images
  1. docker save -o local-images.tar image1:tag1 image2:tag2
  • Save all local images

Below two commands use jq for JSON parsing. The long command performs the below steps:

  • The docker image ls sub command gets the list of all local images.
  • The jq sub command filters and formats the images list from the previous step.
    • The select(.Repository!=\"<none>\") part of the command skips those images with repository having a value of <none>.
    • The if (.Tag=="<none>") then .Repository else (.Repository+":"+.Tag) end') part of the command formats the name of the images to be just the <Repository> or <Repository>:<Tag> depending on whether a image tag has a value of <none> or not.

  • Finally the docker save -o all-local-images-in-namespace.tar part of the command saves the filtered and formatted images list from the previous two steps into a tar file.

  • Bash

  • PowerShell
  1. docker save -o all-local-images-in-namespace.tar $(docker image ls --format '{{json .}}' | jq -r 'select(.Repository!="<none>") | if (.Tag=="<none>") then .Repository else (.Repository+":"+.Tag) end')
  1. docker save -o all-local-images-in-namespace.tar $(docker image ls --format '{{json .}}' | jq -r 'select(.Repository!=\"<none>\") | if (.Tag==\"<none>\") then .Repository else (.Repository+\":\"+.Tag) end')

2. Load images from the saved tar archive in the target environment.

  • nerdctl
  • docker
  1. nerdctl load < local-images.tar
  1. docker load < local-images.tar