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/** * MCP Serve Command * * DESIGN PATTERNS: * - Command pattern with Commander for CLI argument parsing * - Transport abstraction pattern for flexible deployment (stdio, HTTP, SSE) * - Factory pattern for creating transport handlers * - Graceful shutdown pattern with signal handling * * CODING STANDARDS: * - Use async/await for asynchronous operations * - Implement proper error handling with try-catch blocks * - Handle process signals for graceful shutdown * - Provide clear CLI options and help messages * * AVOID: * - Hardcoded configuration values (use CLI options or environment variables) * - Missing error handling for transport startup * - Not cleaning up resources on shutdown */ import { Command } from 'commander'; import { createServer } from '../server'; import { StdioTransportHandler } from '../transports/stdio'; import { HttpTransportHandler } from '../transports/http'; import { SseTransportHandler } from '../transports/sse'; import { type TransportConfig, type TransportHandler, TRANSPORT_MODE } from '../types'; import { findConfigFile } from '../utils'; /** * Valid transport types for the MCP server */ type ValidTransportType = 'stdio' | 'http' | 'sse'; /** * Type guard to validate transport type * @param type - The transport type string to validate * @returns True if the type is a valid transport type */ function isValidTransportType(type: string): type is ValidTransportType { return type === 'stdio' || type === 'http' || type === 'sse'; } /** * Options for the mcp-serve command */ interface McpServeOptions { type: string; port: number; host: string; config?: string; cache: boolean; } /** * Start MCP server with given transport handler * @param handler - The transport handler to start */ async function startServer(handler: TransportHandler): Promise<void> { await handler.start(); // Handle graceful shutdown const shutdown = async (signal: string): Promise<void> => { console.error(`\nReceived ${signal}, shutting down gracefully...`); try { await handler.stop(); process.exit(0); } catch (error) { console.error('Error during shutdown:', error); process.exit(1); } }; process.on('SIGINT', () => shutdown('SIGINT')); process.on('SIGTERM', () => shutdown('SIGTERM')); } /** * MCP Serve command */ export const mcpServeCommand = new Command('mcp-serve') .description('Start MCP server with specified transport') .option('-t, --type <type>', 'Transport type: stdio, http, or sse', 'stdio') .option( '-p, --port <port>', 'Port to listen on (http/sse only)', (val) => parseInt(val, 10), 3000, ) .option('--host <host>', 'Host to bind to (http/sse only)', 'localhost') .option('-c, --config <path>', 'Path to MCP server configuration file') .option('--no-cache', 'Disable configuration caching, always reload from config file') .action(async (options: McpServeOptions): Promise<void> => { const transportType = options.type.toLowerCase(); // Validate transport type if (!isValidTransportType(transportType)) { console.error(`Unknown transport type: '${transportType}'. Valid options: stdio, http, sse`); process.exit(1); } try { // Find config file: use provided path, or search PROJECT_PATH then cwd const configFilePath = options.config || findConfigFile() || undefined; const serverOptions = { configFilePath, noCache: options.cache === false, // Commander transforms --no-cache to cache: false }; if (transportType === 'stdio') { const server = await createServer(serverOptions); const handler = new StdioTransportHandler(server); await startServer(handler); } else if (transportType === 'http') { // For HTTP, pass the server instance directly (handler will create sessions) const server = await createServer(serverOptions); const config: TransportConfig = { mode: TRANSPORT_MODE.HTTP, port: options.port || Number(process.env.MCP_PORT) || 3000, host: options.host || process.env.MCP_HOST || 'localhost', }; const handler = new HttpTransportHandler(server, config); await startServer(handler); } else if (transportType === 'sse') { // For SSE, pass the server instance directly (handler will create sessions) const server = await createServer(serverOptions); const config: TransportConfig = { mode: TRANSPORT_MODE.SSE, port: options.port || Number(process.env.MCP_PORT) || 3000, host: options.host || process.env.MCP_HOST || 'localhost', }; const handler = new SseTransportHandler(server, config); await startServer(handler); } } catch (error) { console.error( `Failed to start MCP server with transport '${transportType}' on ${options.host}:${options.port}:`, error, ); process.exit(1); } });