I am getting an error when using websocket.

[jclab-joseph]

serverless.yaml:

plugins:
  - serverless-plugin-typescript
  - serverless-apigw-binary
  - serverless-offline

functions:
  api:
    handler: src/index.handler
    events:
      - http:
          path: /{proxy+}
          method: any
      - websocket:
          route: $connect
          #routeResponseSelectionExpression: $default # optional, setting this enables callbacks on websocket requests for two-way communication
      - websocket:
          route: $disconnect

  TypeError: Cannot read property 'replace' of undefined
      at getPathWithQueryStringParams (D:\project\node_modules\@vendia\serverless-express\src\event-sources\utils.js:13:20)
      at getRequestValuesFromEvent (D:\project\node_modules\@vendia\serverless-express\src\event-sources\utils.js:29:10)
      at Object.getRequestValuesFromApiGatewayEvent [as getRequest] (D:\project\node_modules\@vendia\serverless-express\src\event-sources\aws\api-gateway-v
1.js:3:60)
      at forwardRequestToNodeServer (D:\project\node_modules\@vendia\serverless-express\src\transport.js:147:37)
      at D:\project\node_modules\@vendia\serverless-express\src\configure.js:73:9
      at new Promise (<anonymous>)
      at proxy (D:\project\node_modules\@vendia\serverless-express\src\configure.js:60:12)
      at handler (D:\project\node_modules\@vendia\serverless-express\src\configure.js:99:12)
      at D:\project\.build\src\index.js:59:12
      at Generator.next (<anonymous>)
      at fulfilled (D:\project\.build\src\index.js:5:58)
      at processTicksAndRejections (internal/process/task_queues.js:93:5)

event & context:

{
  event: {
    headers: {
      Host: '127.0.0.1:3001',
      Connection: 'Upgrade',
      Pragma: 'no-cache',
      'Cache-Control': 'no-cache',
      'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36',
      Upgrade: 'websocket',
      Origin: 'http://127.0.0.1:3000',
      'Sec-WebSocket-Version': '13',
      'Accept-Encoding': 'gzip, deflate, br',
      'Accept-Language': 'ko-KR,ko;q=0.9',
      'Sec-WebSocket-Key': '4R8Snu0qu8Hyp8X4CfBxjA==',
      'Sec-WebSocket-Extensions': 'permessage-deflate; client_max_window_bits'
    },
    isBase64Encoded: false,
    multiValueHeaders: {
      Host: [Array],
      Connection: [Array],
      Pragma: [Array],
      'Cache-Control': [Array],
      'User-Agent': [Array],
      Upgrade: [Array],
      Origin: [Array],
      'Sec-WebSocket-Version': [Array],
      'Accept-Encoding': [Array],
      'Accept-Language': [Array],
      Cookie: [Array],
      'Sec-WebSocket-Key': [Array],
      'Sec-WebSocket-Extensions': [Array]
    },
    requestContext: {
      apiId: 'private',
      connectedAt: 1636205815771,
      connectionId: 'ckvnup3h600006gvw5xz82fey',
      domainName: 'localhost',
      eventType: 'CONNECT',
      extendedRequestId: 'ckvnup3h700016gvw4571bpes',
      identity: [Object],
      messageDirection: 'IN',
      messageId: 'ckvnup3h700026gvwb7ep3kv8',
      requestId: 'ckvnup3h700036gvw1jtv3z4y',
      requestTime: '06/Nov/2021:22:36:55 +0900',
      requestTimeEpoch: 1636205815771,
      routeKey: '$connect',
      stage: 'local'
    }
  },
  context: {
    awsRequestId: 'ckvnup3hb00046gvwf3qa4bl3',
    callbackWaitsForEmptyEventLoop: true,
    clientContext: null,
    functionName: 'blog-post-dev-api',
    functionVersion: '$LATEST',
    identity: undefined,
    invokedFunctionArn: 'offline_invokedFunctionArn_for_blog-post-dev-api',
    logGroupName: 'offline_logGroupName_for_blog-post-dev-api',
    logStreamName: 'offline_logStreamName_for_blog-post-dev-api',
    memoryLimitInMB: '1024',
    getRemainingTimeInMillis: [Function: getRemainingTimeInMillis],
    done: [Function: done],
    fail: [Function: fail],
    succeed: [Function: succeed]
  }
}

Is there any way to use websockets?

[H4ad]

It seems that vendia/serverless-express does not support websockets as an event source, only REST and HTTP API in Api Gateway.

But you can create an event source to parse your event, like DynamoDB example. Read the code from api-gateway-v1 because your event is being recognized as a event from api gateway v1.

You can get more ideas on how to implement it by looking at this AWS SNS implementation.

[tylerzey]

I was able to get around it by modifying the event in place.

Not ideal, but it works for my use case.

const apiGatewayGraphQLHandler: APIGatewayProxyHandler = async (event, context, callback) => {
  // eslint-disable-next-line no-console
  console.log(event);

  if (!event.body) {
    return buildErrorWSResponse('Body required');
  }

  const parsedBody = JSON.parse(event.body);

  if (parsedBody.type === 'connection_init') {
    return await handleWSEventRequest(event);
  }

  event.body = JSON.stringify(parsedBody?.payload ? parsedBody?.payload : parsedBody);

  return serverlessExpressInstance(event, context);
};