Docker Registry Distribution

The Distribution project (formerly Docker Distribution or Docker Registry v2) is the toolkit to pack, ship, store, and deliver container images and other content, providing the reference implementation of the OCI Distribution Specification. Originally developed by Docker Inc. in 2014, donated to the CNCF in 2021, and graduated as a CNCF project, the Distribution project powers Docker Hub, GitHub Container Registry, GitLab Registry, and countless private registries. Key features include: OCI Distribution Spec compliance (reference implementation of the Open Container Initiative Distribution Specification, ensuring interoperability with all OCI-compatible container runtimes including containerd, CRI-O, and Docker), registry server (HTTP server handling pull, push, manifest, blob, tag, and catalog operations with content-addressable storage using SHA-256 digests), storage drivers (filesystem, in-memory, Amazon S3, Microsoft Azure, Google Cloud Storage, OpenStack Swift, and Alibaba OSS), authentication (token-based authentication with Bearer token, OAuth2, and integration with Docker Hub, Auth0, Keycloak, and custom auth services), garbage collection (mark-and-sweep garbage collection to remove unreferenced blobs and manifests), content discovery (catalog API for listing repositories and tag listing API for available image tags), manifest formats (support for OCI Image Manifest, Docker Image Manifest V2 Schema 2, and Schema 1 for backwards compatibility), webhooks (notification system sending HTTP POST events on push, pull, and manifest operations), read-only mode (maintenance mode preventing writes while allowing reads), TLS and HTTP (configurable HTTPS with certificate management), and middleware (extensible middleware for cloud storage, redirects, and custom authentication).