[CPL-20711] add http server transport option

Author: oshchyhol

src/env.ts

@@ -13,6 +13,7 @@ export const {
   APP_VERSION,
   TRANSPORT,
   AUTHORIZATION_SERVER_HOST,
+  PORT,
 } = parseEnv(process.env, {
     COUPLER_API_HOST: z.string().url().default('https://app.coupler.io'),
     COUPLER_ACCESS_TOKEN: z.string().trim().min(1),
@@ -21,5 +22,6 @@ export const {
     NODE_ENV: z.enum(ENVS).default('development'),
     APP_VERSION: z.string().trim().min(1),
     TRANSPORT: z.enum(TRANSPORTS).default('stdio'),
-    AUTHORIZATION_SERVER_HOST: z.string().url().default('https://auth.coupler.io')
+    AUTHORIZATION_SERVER_HOST: z.string().url().default('https://auth.coupler.io'),
+    PORT: z.number().default(3001)
   })

src/index.ts

@@ -1,18 +1,11 @@
-import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
-import { server } from '@/server'
-import { logger } from '@/logger'
+import { TRANSPORT } from '@/env'
+import { stdioServer } from '@/server/transports/stdio'
+import { httpServer } from '@/server/transports/http'
 
 const main = () => {
-  const transport = new StdioServerTransport()
-  server.connect(transport)
-    .then(() => {
-      logger.info('Coupler.io MCP Server started')
-      server.sendLoggingMessage({ level: 'info', data: 'Coupler.io MCP Server started' })
-    })
-    .catch((e) => {
-      logger.error('Fatal error: ', e)
-      process.exit(1)
-    })
+  const server = TRANSPORT === 'stdio' ? stdioServer : httpServer
+
+  server.start()
 }
 
 main()

src/server/transports/http/index.ts

@@ -0,0 +1,24 @@
+import express from 'express'
+
+import { PORT } from '@/env'
+import { loggingMiddleware, logger } from '@/server/logging'
+import { router as mcpRouter } from '@/server/transports/http/routes/mcp'
+import { router as oauthRouter } from '@/server/transports/http/routes/oauth'
+
+const app = express()
+
+app.disable('x-powered-by')
+
+app.use(express.json())
+app.use(loggingMiddleware)
+
+app.use('/mcp', mcpRouter)
+app.use('/oauth', oauthRouter)
+
+export const httpServer = {
+  start() {
+    app.listen(PORT, () => {
+      logger.info(`Coupler.io MCP Server listening on port ${PORT}`)
+    })
+  }
+}

src/server/transports/http/middleware/authorize.ts

@@ -0,0 +1,12 @@
+import type { Request, Response, NextFunction } from 'express'
+
+export const authorize = (req: Request, res: Response, next: NextFunction): void => {
+  const token = req.header('Authorization')?.split(/\s+/)[1]
+
+  if (!token) {
+    res.status(401).json({ message: 'Unauthorized' })
+    return
+  }
+
+  next()
+}

src/server/transports/http/routes/mcp/index.ts

@@ -0,0 +1,54 @@
+import { Router } from 'express'
+import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js'
+
+import { server } from '@/server/index'
+import { logger } from '@/server/logging'
+import { authorize } from '@/server/transports/http/middleware/authorize'
+
+const methodNotAllowedResponse = {
+  jsonrpc: '2.0',
+  error: {
+    code: -32000,
+    message: 'Method not allowed.'
+  },
+}
+
+const router = Router()
+
+router.use(authorize)
+
+router.post('/', async (req, res) => {
+  try {
+    const transport: StreamableHTTPServerTransport = new StreamableHTTPServerTransport({
+      sessionIdGenerator: undefined,
+    })
+
+    res.on('close', () => {
+      transport.close()
+      server.close()
+    })
+
+    await server.connect(transport)
+    await transport.handleRequest(req, res, req.body)
+  } catch (error) {
+    logger.error('Error handling MCP request:', error)
+    if (!res.headersSent) {
+      res.status(500).json({
+        jsonrpc: '2.0',
+        error: {
+          code: -32603,
+          message: 'Internal server error',
+        },
+        id: null,
+      })
+    }
+  }
+})
+
+router.use((req, res) => {
+  if (req.method != 'POST') {
+    res.status(405).json(methodNotAllowedResponse)
+  }
+})
+
+export { router }

src/server/transports/http/routes/oauth/index.ts

@@ -0,0 +1,16 @@
+import { AUTHORIZATION_SERVER_HOST } from '@/env'
+import { Router } from 'express'
+
+const router = Router()
+
+const body = {
+  registration_endpoint: `${AUTHORIZATION_SERVER_HOST}/oauth2/applications`,
+  token_endpoint: `${AUTHORIZATION_SERVER_HOST}/oauth2/token`,
+  authorization_endpoint: `${AUTHORIZATION_SERVER_HOST}/oauth2/authorize`
+}
+
+router.get('/.well-known/oauth-authorization-server', (_req, res) => {
+  res.json(body)
+})
+
+export { router }

src/server/transports/stdio/index.ts

@@ -0,0 +1,20 @@
+import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
+import { server } from '@/server/index'
+import { logger } from '@/server/logging'
+
+export const stdioServer = {
+  start() {
+    const transport = new StdioServerTransport()
+    server.connect(transport)
+      .then(() => {
+        logger.info('Coupler.io MCP Server started')
+        server.sendLoggingMessage({ level: 'info', data: 'Coupler.io MCP Server started' })
+      })
+      .catch((e) => {
+        logger.error('Fatal error: ', e)
+        process.exit(1)
+      })
+  }
+}
+
+