feat(runtime): support interceptor function #341 (#579)

runtimes/nodejs/src/handler/invoke-func.ts

@@ -14,15 +14,24 @@ import { handleDebugFunction } from './debug-func'
 import { parseToken } from '../support/token'
 
 const DEFAULT_FUNCTION_NAME = '__default__'
+const INTERCEPTOR_FUNCTION_NAME = '__interceptor__'
 
 /**
  * Handler of invoking cloud function
  */
 export async function handleInvokeFunction(req: IRequest, res: Response) {
+  // intercept the request, skip websocket request
+  if (false === req.method.startsWith('WebSocket')) {
+    const passed = await invokeInterceptor(req, res)
+    if (passed === false) return
+  }
+
+  // debug mode
   if (req.get('x-laf-debug-token')) {
     return await handleDebugFunction(req, res)
   }
 
+  // trigger mode
   let isTrigger = false
   if (parseToken(req.get('x-laf-trigger-token'))) {
     isTrigger = true
@@ -93,3 +102,70 @@ export async function handleInvokeFunction(req: IRequest, res: Response) {
     return res.status(500).send('Internal Server Error')
   }
 }
+
+async function invokeInterceptor(req: IRequest, res: Response) {
+  const requestId = req.requestId
+  const func_name = INTERCEPTOR_FUNCTION_NAME
+
+  // load function data from db
+  let funcData = await CloudFunction.getFunctionByName(func_name)
+  // pass if no interceptor
+  if (!funcData) {
+    return true
+  }
+
+  const func = new CloudFunction(funcData)
+
+  try {
+    // execute the func
+    const ctx: FunctionContext = {
+      query: req.query,
+      files: req.files as any,
+      body: req.body,
+      headers: req.headers,
+      method: req.method,
+      auth: req['auth'],
+      user: req.user,
+      requestId,
+      request: req,
+      response: res,
+      __function_name: func.name,
+    }
+    const result = await func.invoke(ctx)
+
+    // return false to reject request if interceptor got error
+    if (result.error) {
+      logger.error(
+        requestId,
+        `invoke function ${func_name} invoke error: `,
+        result,
+      )
+
+      res.status(400).send({
+        error: `invoke ${func_name} function got error, please check the function logs`,
+        requestId,
+      })
+
+      return false
+    }
+
+    // if response has been ended, return false to stop the request
+    if (res.writableEnded) {
+      return false
+    }
+
+    // reject request if interceptor return false
+    if (false === result.data) {
+      res.status(403).send({ error: 'Forbidden', requestId })
+      return false
+    }
+
+    // pass the request
+    return result.data
+  } catch (error) {
+    logger.error(requestId, `failed to invoke ${func_name}`, error)
+    return res
+      .status(500)
+      .send(`Internal Server Error - got error in ${func_name}`)
+  }
+}