A Docker tool, modelled on containerd's architecture.

• Copy container images between registries with progress reporting
• Inspect image metadata without pulling image layers
• List tags for an image repository
• Supports OCI Image Spec and Docker Schema 2 wire formats
• Multi-platform manifest index support (--all or --platform)
• Reads credentials from ~/.docker/config.json automatically

dtool copy docker://ubuntu:22.04 docker://myregistry.io/ubuntu:22.04

Copy all platforms from a manifest index:

dtool copy --all docker://ubuntu:22.04 docker://myregistry.io/ubuntu:22.04

Copy a specific platform:

dtool copy --platform linux/arm64 docker://ubuntu:22.04 docker://myregistry.io/ubuntu:22.04

dtool inspect docker://ubuntu:22.04

Print raw manifest or config JSON:

dtool inspect --raw docker://ubuntu:22.04
dtool inspect --config docker://ubuntu:22.04

dtool list-tags docker://ubuntu

References use a TRANSPORT:REFERENCE notation. The docker:// transport is the only one fully implemented. When no transport prefix is given, docker:// is assumed.

docker://registry.io/image:tag
docker://registry.io/image@sha256:<digest>

Credentials are resolved in this order:

1. --src-creds USER:PASS / --dest-creds USER:PASS / --creds USER:PASS CLI flags
2. ~/.docker/config.json (the auth field or username/password fields)

Note: External credential helpers (e.g. docker-credential-desktop) are not currently supported.

dtool mirrors containerd's architecture in Rust:

• Resolver, Fetcher, and Pusher traits map to containerd's core/remotes/ interfaces
• Descriptor, Manifest, Index model OCI and Docker Schema 2 wire formats
• Platform matching follows the same rules as github.com/containerd/platforms

The registry HTTP client is implemented in Go (go/libdtool.go) using containerd's core/remotes/docker package and compiled into a static C archive (libdtool_go.a) that is linked into the Rust binary at build time.