docker export / docker import#

These operate on containers and export a snapshot of the container’s current filesystem.

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# Export container snapshot
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docker export container-id > snapshot.tar
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# Import as an image
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docker import snapshot.tar new-image-name:tag

Characteristics:

• Only retains filesystem changes made from container start to export — discards history layers and metadata
• Smaller file size (single filesystem layer)
• Must specify a new image name and tag on import
• Imported images require /bin/bash or another entrypoint on start

Use case: Creating base images. For example, start a container from ubuntu, install software, then export it as a distributable base image.

docker commit#

Operates on containers, saving modifications as a new image.

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docker commit container-id new-image-name:tag

Common options:

• -a: Author information
• -m: Commit message
• -p: Pause the container during commit

Characteristics:

• Preserves the container’s writable layer plus the original image’s history layers
• An N-layer image becomes N+1 layers after commit
• Retains metadata like the entrypoint command

Use case: Quickly save changes from a debugging environment to create a reusable image.

docker save / docker load#

Operate on images, exporting the complete layer structure.

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# Save an image
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docker save -o image.tar image-name:tag
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# Load an image
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docker load -i image.tar

Characteristics:

• Preserves the full layer structure and metadata
• Larger file size than export (includes all history layers)
• load cannot rename the image, while import can assign a new name

Use case: Offline image migration. On a server without internet, pull the image on a connected machine, save it, copy the archive, then load it on the target server.

Comparison Summary#

Quick memory aid: save/load work with images, export/import work with containers, and commit is the bridge from container → image.