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An SSE-based MCP server that allows LLM-powered applications to interact with OCI registries. It provides tools for retrieving information about container images, listing tags, and more.

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OCI Registry MCP Server

Trust Score An MCP (Model Context Protocol) server that provides tools for querying OCI registries and image references.

Overview

This project implements an SSE-based MCP server that allows LLM-powered applications to interact with OCI registries. It provides tools for retrieving information about container images, listing tags, and more.

Features

  • Get information about OCI images
  • List tags for repositories
  • Get image manifests
  • Get image configs

MCP Tools

The server provides the following MCP tools:

get_image_info

Get information about an OCI image.

Input:

  • image_ref: The image reference (e.g., docker.io/library/alpine:latest)

Output:

  • Image information including digest, size, architecture, OS, creation date, and number of layers

list_tags

List tags for a repository.

Input:

  • repository: The repository name (e.g., docker.io/library/alpine)

Output:

  • List of tags for the repository

get_image_manifest

Get the manifest for an OCI image.

Input:

  • image_ref: The image reference (e.g., docker.io/library/alpine:latest)

Output:

  • The image manifest

get_image_config

Get the config for an OCI image.

Input:

  • image_ref: The image reference (e.g., docker.io/library/alpine:latest)

Output:

  • The image config

Development

Prerequisites

  • Go 1.21 or later
  • Access to OCI registries

Authentication

The server supports the following authentication methods for accessing private OCI registries (in order of priority):

  1. HTTP Authorization Header (Highest Priority): Include a bearer token in the HTTP request's Authorization header:

    • Authorization: Bearer <your-token>
    • This method takes precedence over all other authentication methods
    • When present, environment variables and Docker config are ignored

  2. Bearer Token Environment Variable: Set the following environment variable:

    • OCI_TOKEN: Bearer token for registry authentication

  3. Username and Password: Set the following environment variables:

    • OCI_USERNAME: Username for registry authentication
    • OCI_PASSWORD: Password for registry authentication

  4. Docker Config (Lowest Priority): If no other authentication is provided, the server will use the default Docker keychain, which reads credentials from ~/.docker/config.json.

Examples:

# HTTP Authorization header (for per-request authentication)
# This is handled automatically by the MCP client when making requests
# Example: curl -H "Authorization: Bearer mytoken" http://localhost:8080/...

# Bearer token authentication via environment variable
export OCI_TOKEN=mytoken

# Username/password authentication via environment variables
export OCI_USERNAME=myuser
export OCI_PASSWORD=mypassword

Port Configuration

The server can be configured to listen on a specific port using either:

  1. Environment Variable:

    • MCP_PORT: The port number to listen on (must be between 0 and 65535)
    • If not set or invalid, defaults to port 8080

  2. Command-line Flag:

    • -port: Overrides the environment variable setting (must be between 0 and 65535)
    • If invalid port provided it defaults to port 8080
    • Example: ./ocireg-mcp -port 9090

Testing

go test ./...

Linting

golangci-lint run