MCR

Metacircular Container Registry -- an OCI Distribution Spec-compliant container registry for the Metacircular platform. MCR stores and serves container images with authentication delegated to MCIAS and a local policy engine for fine-grained access control. Metadata is stored in SQLite; blobs are stored as content-addressed files on the filesystem.

Quick Start

Build the binaries:

make all

This produces three binaries:

Binary	Purpose
mcrsrv	Registry server (OCI + admin REST + gRPC)
mcr-web	Web UI (htmx, communicates with mcrsrv via gRPC)
mcrctl	Admin CLI

Copy and edit the example configuration:

cp deploy/examples/mcr.toml /srv/mcr/mcr.toml
# Edit TLS paths, database path, storage paths, MCIAS URL

Run the server:

./mcrsrv server --config /srv/mcr/mcr.toml

The server starts two listeners:

Port	Protocol	Purpose
8443	TCP	HTTPS -- OCI Distribution endpoints + admin REST API
9443	TCP	gRPC admin API (TLS, MCIAS auth)

Run the web UI:

./mcr-web server --config /srv/mcr/mcr.toml

Port	Protocol	Purpose
8080	TCP	HTTP -- web UI (repository browsing, policy management)

Documentation

• ARCHITECTURE.md -- full technical specification, OCI compliance details, database schema, policy engine, and security model.
• RUNBOOK.md -- operational procedures, health checks, backup/restore, incident response, and MCP deployment.
• CLAUDE.md -- context for AI-assisted development.