GitHub App MCP gateway

This is a local stdio MCP gateway for the official github-mcp-server. It adds a required, nullable scope argument to every proxied GitHub tool, resolves the GitHub App installation through GitHub's API, and starts one downstream server per active installation. Downstream servers are stopped when the client session closes.

Configure

Copy config.example.yaml to config.yaml. The YAML file deliberately contains only gateway-owned settings: the GitHub MCP executable, the GitHub App private-key path and the default installation used for explicit scope: null.

Set appId in the YAML configuration. Every environment variable supplied by the MCP client is forwarded to each github-mcp-server child, except values owned by the gateway. The gateway deliberately overrides only:

• GITHUB_APP_ID, selected from YAML;

• GITHUB_APP_INSTALLATION_ID, selected from scope;

• GITHUB_APP_PRIVATE_KEY_PATH, selected from YAML;

• GITHUB_APP_PRIVATE_KEY, removed so the configured key path is authoritative.

All gateway command-line arguments after -- are forwarded unchanged to the GitHub MCP server. The gateway adds stdio when it is not already present.

Related MCP server: @brycepelletier/github-app-mcp

Build and register

npm install
npm run build

Example client configuration:

{
  "command": "node",
  "args": [
    "/path/to/github-app-mcp-gateway/dist/index.js",
    "--config", "/path/to/github-app-mcp-gateway/config.yaml",
    "--",
    "--toolsets", "repos,issues,pull_requests"
  ],
  "env": {
    "GITHUB_HOST": "https://github.com",
    "GITHUB_API_URL": "https://api.github.com",
    "GITHUB_LOCKDOWN_MODE": "0"
  }
}

The scope argument is required, but candidate scopes are deliberately not enumerated in the tool definition. Pass a repository (owner/repo), organization, or user name and the gateway will query GitHub for this App's installation ID; use null only for an operation intentionally allowed through the configured default installation. For repository and organization tools, the gateway rejects a scope that does not match the original owner/repo/org arguments.