Email MCP

#!/usr/bin/env node /** * index.ts * * Run MCP stdio servers over SSE, convert between stdio, SSE, WS. * * Usage: * # stdio→SSE * npx -y supergateway --stdio "npx -y @modelcontextprotocol/server-filesystem /" \ * --port 8000 --baseUrl http://localhost:8000 --ssePath /sse --messagePath /message * * # SSE→stdio * npx -y supergateway --sse "https://mcp-server-ab71a6b2-cd55-49d0-adba-562bc85956e3.supermachine.app" * * # stdio→WS * npx -y supergateway --stdio "npx -y @modelcontextprotocol/server-filesystem /" --outputTransport ws */ import yargs from 'yargs' import { hideBin } from 'yargs/helpers' import { stdioToSse } from './gateways/stdioToSse.js' import { sseToStdio } from './gateways/sseToStdio.js' import { stdioToWs } from './gateways/stdioToWs.js' import { headers } from './lib/headers.js' import { corsOrigin } from './lib/corsOrigin.js' import { getLogger } from './lib/getLogger.js' async function main() { const argv = yargs(hideBin(process.argv)) .option('stdio', { type: 'string', description: 'Command to run an MCP server over Stdio', }) .option('sse', { type: 'string', description: 'SSE URL to connect to', }) .option('outputTransport', { type: 'string', choices: ['stdio', 'sse', 'ws'], default: () => { const args = hideBin(process.argv) if (args.includes('--stdio')) return 'sse' if (args.includes('--sse')) return 'stdio' return undefined }, description: 'Transport for output. Default is "sse" when using --stdio and "stdio" when using --sse.', }) .option('port', { type: 'number', default: 8000, description: '(stdio→SSE, stdio→WS) Port for output MCP server', }) .option('baseUrl', { type: 'string', default: '', description: '(stdio→SSE) Base URL for output MCP server', }) .option('ssePath', { type: 'string', default: '/sse', description: '(stdio→SSE) Path for SSE subscriptions', }) .option('messagePath', { type: 'string', default: '/message', description: '(stdio→SSE, stdio→WS) Path for messages', }) .option('logLevel', { choices: ['debug', 'info', 'none'] as const, default: 'info', description: 'Logging level', }) .option('cors', { type: 'array', description: 'Enable CORS. Use --cors with no values to allow all origins, or supply one or more allowed origins (e.g. --cors "http://example.com" or --cors "/example\\.com$/" for regex matching).', }) .option('healthEndpoint', { type: 'array', default: [], description: 'One or more endpoints returning "ok", e.g. --healthEndpoint /healthz --healthEndpoint /readyz', }) .option('header', { type: 'array', default: [], description: 'Headers to be added to the request headers, e.g. --header "x-user-id: 123"', }) .option('oauth2Bearer', { type: 'string', description: 'Authorization header to be added, e.g. --oauth2Bearer "some-access-token" adds "Authorization: Bearer some-access-token"', }) .help() .parseSync() const hasStdio = Boolean(argv.stdio) const hasSse = Boolean(argv.sse) const logger = getLogger({ logLevel: argv.logLevel, outputTransport: argv.outputTransport as string, }) if (hasStdio && hasSse) { logger.error('Error: Specify only one of --stdio or --sse, not all') process.exit(1) } else if (!hasStdio && !hasSse) { logger.error('Error: You must specify one of --stdio or --sse') process.exit(1) } logger.info('Starting...') logger.info( 'Supergateway is supported by Supermachine (hosted MCPs) - https://supermachine.ai', ) logger.info(` - outputTransport: ${argv.outputTransport}`) try { if (hasStdio) { if (argv.outputTransport === 'sse') { await stdioToSse({ stdioCmd: argv.stdio!, port: argv.port, baseUrl: argv.baseUrl, ssePath: argv.ssePath, messagePath: argv.messagePath, logger, corsOrigin: corsOrigin({ argv }), healthEndpoints: argv.healthEndpoint as string[], headers: headers({ argv, logger, }), }) } else if (argv.outputTransport === 'ws') { await stdioToWs({ stdioCmd: argv.stdio!, port: argv.port, messagePath: argv.messagePath, logger, corsOrigin: corsOrigin({ argv }), healthEndpoints: argv.healthEndpoint as string[], }) } else { logger.error(`Error: stdio→${argv.outputTransport} not supported`) process.exit(1) } } else if (hasSse) { if (argv.outputTransport === 'stdio') { await sseToStdio({ sseUrl: argv.sse!, logger, headers: headers({ argv, logger, }), }) } else { logger.error(`Error: sse→${argv.outputTransport} not supported`) process.exit(1) } } else { logger.error('Error: Invalid input transport') process.exit(1) } } catch (err) { logger.error('Fatal error:', err) process.exit(1) } } main()