Save and Load Images

Learn how to export Docker images and containers to tar archives, move them into air-gapped or restricted environments, and load or import them back into Docker without direct internet access.

Table of Contents

1. Exporting and Transferring Docker Images
2. Exporting a Container Filesystem and Importing as an Image
3. Docker CLI Reference
4. Links and References

1. Exporting and Transferring Docker Images

When you cannot pull directly from Docker Hub (for example, in a restricted environment), follow these steps:

Step-by-Step Guide

1. Pull the desired image on an internet-connected host:

   docker pull alpine:latest
   

2. Save the image into a tarball:

   docker image save alpine:latest -o alpine.tar
   

3. Transfer alpine.tar to the target system (USB drive, SCP, shared NFS, etc.).
4. Load the tarball on the restricted host:

   docker image load -i alpine.tar
   

   You should see output similar to:

   beee9f30bc1f: Loading layer [==================>]  5.862MB/5.862MB
   Loaded image: alpine:latest
   

5. Confirm the image is available locally:

   docker image ls
   

   Example output:

   REPOSITORY   TAG       IMAGE ID       CREATED        SIZE
   alpine       latest    a187dde48cd2   4 weeks ago    5.6MB
   

2. Exporting a Container Filesystem and Importing as an Image

You can snapshot a running container’s filesystem and convert it into a new Docker image:

1. Export the container to a tar archive:

   docker export <container-name> > testcontainer.tar
   

2. Import the tarball as a fresh image:

   docker image import testcontainer.tar newimage:latest
   

   Docker returns a new image ID, e.g.:

   sha256:8909b7da236bb21aa2e52e6e04dff4b7103753e4046e15457a3daf6dfa723a12
   

3. List local images to confirm the import:

   docker image ls
   

   Example output:

   REPOSITORY    TAG       IMAGE ID       CREATED         SIZE
   newimage      latest    8090b7da236b   2 minutes ago   5.6MB
   alpine        latest    a187dde48cd2   4 weeks ago     5.6MB
   

Docker CLI Reference

Links and References

• Docker Save Command
• Docker Load Command
• Docker Export and Import
• Docker CLI Overview