How to Import and Export Docker Images for Migration

Import and Export via Image (docker load / docker save)

Docker provides load and save commands to import and export images as tar archives.

docker load reads an image from a tar file or STDIN. docker load --help Usage: docker load [OPTIONS] Key options: -i, --input string – read from a tar archive file instead of STDIN. -q, --quiet – suppress output.

Example importing from a file: docker load -i nginx.tar Or using a pipe: docker load < nginx.tar Both forms import the image together with its metadata and tag information.

docker save writes one or more images to a tar archive (STDOUT by default). docker save --help Usage: docker save [OPTIONS] IMAGE [IMAGE...] Key option: -o, --output string – write to a file instead of STDOUT.

Example saving to a file: docker save -o nginx.tar nginx:latest Or redirecting output: docker save > nginx.tar nginx:latest Here nginx.tar is the target file and nginx:latest is the source image (name:tag).

Import and Export via Container (docker import / docker export)

Docker also supports importing and exporting a container's filesystem.

docker import creates an image from a tarball or URL. docker import --help Usage:

docker import [OPTIONS] file|URL|- [REPOSITORY[:TAG]]

Key options: -c, --change list – apply Dockerfile instructions to the created image. -m, --message string – set a commit message for the imported image.

Example importing a tar file as an image named nginx:imp : docker import nginx-test.tar nginx:imp Or using a pipe: cat nginx-test.tar | docker import - nginx:imp docker export streams a container's filesystem as a tar archive. docker export --help Usage: docker export [OPTIONS] CONTAINER Key option: -o, --output string – write to a file instead of STDOUT.

Example exporting a container named nginx-test to nginx-test.tar : docker export -o nginx-test.tar nginx-test Here -o specifies the output file, nginx-test.tar is the target file, and nginx-test is the source container name.