ATCR - ATProto Container Registry

https://atcr.io

An OCI-compliant container registry that uses the AT Protocol for manifest storage and S3 for blob storage.

What is ATCR?

ATCR integrates container registries with the AT Protocol ecosystem. Container image manifests are stored as ATProto records in your Personal Data Server (PDS), while layers are stored in S3-compatible storage.

Image names use your ATProto identity:

atcr.io/alice.bsky.social/myapp:latest
atcr.io/did:plc:xyz123/myapp:latest

Architecture

Three components:

1. AppView - Registry API + web UI

   • Serves OCI Distribution API (Docker push/pull)
   • Resolves handles/DIDs to PDS endpoints
   • Routes manifests to user's PDS, blobs to hold services
   • Web interface for browsing/search

2. Hold Service - Storage service with embedded PDS (optional BYOS)

   • Each hold has a full ATProto PDS for access control (captain + crew records)
   • Identified by did:web (e.g., did:web:hold01.atcr.io)
   • Generates presigned URLs for S3/Storj/Minio/etc.
   • Users can deploy their own storage and control access via crew membership

3. Credential Helper - Client authentication

   • ATProto OAuth (DPoP handled transparently)
   • Automatic authentication on first push/pull

Storage model:

• Manifests → ATProto records in user's PDS (small JSON, includes holdDid reference)
• Blobs → Hold services via XRPC multipart upload (large binaries, stored in S3/etc.)
• AppView uses service tokens to communicate with holds on behalf of users

Features

• ✅ OCI-compliant - Works with Docker, containerd, podman
• ✅ Decentralized - You own your manifest data via your PDS
• ✅ ATProto OAuth - Secure authentication (DPoP-compliant)
• ✅ BYOS - Deploy your own storage service
• ✅ Web UI - Browse, search, star repositories
• ✅ Multi-backend - S3, Storj, Minio, Azure, GCS, filesystem

Quick Start

Using the Registry

1. Install credential helper:

curl -fsSL https://atcr.io/install.sh | bash

2. Configure Docker (add to ~/.docker/config.json):

{
  "credHelpers": {
    "atcr.io": "atcr"
  }
}

3. Push/pull images:

docker tag myapp:latest atcr.io/yourhandle/myapp:latest
docker push atcr.io/yourhandle/myapp:latest  # Authenticates automatically
docker pull atcr.io/yourhandle/myapp:latest

See INSTALLATION.md for detailed installation instructions.

Running Your Own AppView

Using Docker Compose:

cp .env.appview.example .env.appview
# Edit .env.appview with your configuration
docker-compose up -d

Local development:

# Build
go build -o bin/atcr-appview ./cmd/appview
go build -o bin/atcr-hold ./cmd/hold

# Configure
cp .env.appview.example .env.appview
# Edit .env.appview - set ATCR_DEFAULT_HOLD
source .env.appview

# Run
./bin/atcr-appview serve

See deploy/README.md for production deployment.

Development

Building from Source

# Build all binaries
go build -o bin/atcr-appview ./cmd/appview
go build -o bin/atcr-hold ./cmd/hold
go build -o bin/docker-credential-atcr ./cmd/credential-helper

# Run tests
go test ./...
go test -race ./...

Project Structure

cmd/
├── appview/           # Registry server + web UI
├── hold/              # Storage service (BYOS)
└── credential-helper/ # Docker credential helper

pkg/
├── appview/
│   ├── db/            # SQLite database (migrations, queries, stores)
│   ├── handlers/      # HTTP handlers (home, repo, search, auth, settings)
│   ├── jetstream/     # ATProto Jetstream consumer
│   ├── middleware/    # Auth & registry middleware
│   ├── storage/       # Storage routing (hold cache, blob proxy, repository)
│   ├── public/        # Static assets (JS, CSS, install scripts)
│   └── templates/     # HTML templates
├── atproto/           # ATProto client, records, manifest/tag stores
├── auth/
│   ├── oauth/         # OAuth client, server, refresher, storage
│   ├── token/         # JWT issuer, validator, claims
│   └── atproto/       # Session validation
└── hold/              # Hold service (authorization, storage, multipart, S3)

License

MIT

Contributing

Contributions welcome! Please open an issue or PR.