Skopeo: Pull vs Save

Concepts

Note: Skopeo has no separate pull command; only copy. skopeo copy both fetches and writes the image to a destination.

hpn pull vs hpn save with Skopeo

hpn pull --runtime skopeo

Command executed:

skopeo copy --preserve-digests [--all] docker://image dir:/tmp/skopeo-pull-*

Behavior:

• Destination format: dir: (OCI layout)
• Destination path: /tmp/skopeo-pull-* (temporary directory)
• Cleanup: Directory is removed when the function returns
• Purpose: Verify the image can be pulled; no persistent storage
• Result: Image is written to a temp dir, then that dir is deleted; you cannot inspect it later

hpn save --runtime skopeo

Command executed:

skopeo copy --preserve-digests [--all] docker://image docker-archive:./images/nginx.tar

Behavior:

• Destination format: docker-archive: (tar file)
• Destination path: User-specified (e.g. ./images/nginx.tar)
• Persistence: Files are kept; not deleted
• Purpose: Download and save the image as a tar
• Result: Image is stored as a tar file; you can inspect and reuse it

Comparison

Operation	Destination format	Location	Persistent	Inspectable
hpn pull	dir:	Temp directory	No	No
hpn save	docker-archive:	User path	Yes	Yes

Why does hpn pull not keep the image?

1. Consistency with other runtimes: Docker/Podman "pull" stores in the local daemon; Skopeo has no daemon.
2. Pull = "can we fetch it?": Pull is intended to verify the image is reachable, not to persist it.
3. Use Save to persist: To keep the image, use hpn save.

Usage

Only verify images are pullable

hpn pull --runtime skopeo -f images.txt
# Images are downloaded to a temp dir and then removed.

Download and save as tar

hpn save --runtime skopeo -f images.txt --path ./images
# Inspect: skopeo inspect docker-archive:./images/nginx.tar

Save as directory format (dir:)

Option 1: Use skopeo directly

skopeo copy --preserve-digests --all docker://nginx:latest dir:./images/nginx-latest
skopeo inspect dir:./images/nginx-latest

Option 2: Save with hpn then convert

hpn save --runtime skopeo -f images.txt --path ./images
skopeo copy docker-archive:./images/nginx.tar dir:./images/nginx-latest

Summary

1. Skopeo has no standalone "pull"; only copy, which both fetches and writes.
2. hpn pull: Uses dir: to a temp directory, then deletes it (verification only).
3. hpn save: Uses docker-archive: to the path you specify (persistent).
4. To keep images when using Skopeo, use hpn save, not hpn pull.

See Also

• Skopeo: Images - Inspecting and cleaning Skopeo images
• Examples - Real-world usage