Returns error 400 if lambda outputs anything to stdout

[enolan]

This is a Bug Report

Description

If a lambda function writes anything to stdout, the JSON parser here will fail and a 400 status code will be returned. It should only attempt to parse the last line of stdout as a JSON object, not all of it. In the Node container console.log is intercepted so this only occurs in non-js projects or if you're doing logging that writes to stdout directly.

To reproduce:

• mkdir foo && sls create -t aws-nodejs && npm init
• Hit enter a bunch of times
• npm install --save-dev serverless-plugin-simulate request
• Replace serverless.yml with this:

service: aws-nodejs
provider:
  name: aws
  runtime: nodejs6.10
functions:
  hello:
    handler: handler.hello
    events:
      - http:
          path: hello
          method: get
plugins:
  - serverless-plugin-simulate

• Replace handler.js with this

'use strict';

module.exports.hello = (event, context, callback) => {
  const response = {
    statusCode: 200,
    body: JSON.stringify({
      message: 'Go Serverless v1.0! Your function executed successfully!',
      input: event,
    }),
  };

  process.stdout.write('oh no');
  callback(null, response);
};

• sls simulate apigateway
• in another terminal: curl http://localhost:3000/hello

You should see this in the first terminal:

Serverless: [GET /hello] => λ:hello
Serverless: Invoke URL: http://localhost:3000
Serverless: Creating event
Serverless: Invoking hello
Serverless: Invoking function handler.hello
WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
START RequestId: 4b732836-5d9b-117d-df61-40353e82ede0 Version: $LATEST
oh no
END RequestId: 4b732836-5d9b-117d-df61-40353e82ede0
REPORT RequestId: 4b732836-5d9b-117d-df61-40353e82ede0	Duration: 2.70 ms	Billed Duration: 100 ms	Memory Size: 1024 MB	Max Memory Used: 28 MB	

{"statusCode":200,"body":"{\"message\":\"Go Serverless v1.0! Your function executed successfully!\",\"input\":{\"path\":\"/hello\",\"headers\":{\"host\":\"localhost:3000\",\"user-agent\":\"curl/7.55.1\",\"accept\":\"*/*\"},\"pathParameters\":{},\"requestContext\":{\"accountId\":\"localContext_accountId\",\"resourceId\":\"localContext_resourceId\",\"stage\":\"dev\",\"requestId\":\"localContext_requestId_9738752882301769\",\"identity\":{\"cognitoIdentityPoolId\":\"localContext_cognitoIdentityPoolId\",\"accountId\":\"localContext_accountId\",\"cognitoIdentityId\":\"localContext_cognitoIdentityId\",\"caller\":\"localContext_caller\",\"apiKey\":\"localContext_apiKey\",\"sourceIp\":\"::ffff:127.0.0.1\",\"cognitoAuthenticationType\":\"localContext_cognitoAuthenticationType\",\"cognitoAuthenticationProvider\":\"localContext_cognitoAuthenticationProvider\",\"userArn\":\"localContext_userArn\",\"userAgent\":\"curl/7.55.1\",\"user\":\"localContext_user\"}},\"resource\":\"localContext_resource\",\"httpMethod\":\"GET\",\"queryStringParameters\":{},\"body\":\"{}\",\"stageVariables\":{}}}"}
Serverless: {}
Serverless: Creating error response
GET /hello 400 881.250 ms - 38

And this from curl {"message":"Error executing function"}.

Expected behavior is return a 200 status code. That's what happens on AWS.

lib/invoke/local.js appears to be a copy of index.js from docker-lambda. Or maybe the other way around. This bug is fixed there, in lambci/docker-lambda#17. This plugin should depend on the docker-lambda npm package.

Additional Data

• Serverless Framework Version you're using: 1.26.0
• Serverless Docker Plugin Version you're using: 0.0.17 and HEAD
• Operating System: Ubuntu Linux
• Stack Trace: See above
• Provider Error messages: See above

[enolan]

I have no idea why I thought those two files were the same actually. Working on this now.