Bluebird with Lambda not returning data

1
votes

We have a simple query to fetch information from our database using a serverless application deployed on nodejs. Unfortunately I am not able to get any responses from Bluebird promise - the response always timesout and I'm not sure what could be causing the issue. Below are my files:

serverless.yml:

service: myAuth0

provider:
  name: aws
  iamRoleARN: arn:aws:iam::XXXXXXXXX:role/test-role
  runtime: nodejs4.3
  stage: production
  region: us-us-1
  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "ec2:CreateNetworkInterface"
        - "ec2:DescribeNetworkInterfaces"
        - "ec2:DeleteNetworkInterface"
      Resource: "*"
  vpc:
    securityGroupIds:
      - ${self:custom.${opt:stage, self:provider.stage}.${opt:region, self:provider.region}.vpc.securitygroup}
    subnetIds:
      - ${self:custom.${opt:stage, self:provider.stage}.${opt:region, self:provider.region}.vpc.subnet1}
      - ${self:custom.${opt:stage, self:provider.stage}.${opt:region, self:provider.region}.vpc.subnet2}

custom:
  production:
    us-east-1:
      vpc:
        subnet1: subnet-11111111
        subnet2: subnet-22222222
        securitygroup: sg-33333333

functions:
  getUserRoles:
    handler: app/handler.handle
    events:
      - http:
          method: get
          path: userstest/roles

handler.js:

'use strict';

require('dotenv').config();
var Promise = require('bluebird');
var getConn = require('./dbConn');

module.exports.handle = (event, context, callback) => {
  Promise.using(getConn(), function(conn){
    return conn.query('select ert.name from emp_roles ert order by ert.name').then(function(rows){
      let roles = [];
      rows.forEach(function(row){
        roles.push(row.name);
      });
      return roles;
    }).catch(function(err){
      console.log(error);
    });
  }).then(function(roles){
    console.log("found roles: " + roles);
    callback(null, {roles: roles});
  });
};

dbConn.js:

var mysql = require('promise-mysql');
var pool = mysql.createPool({
  connectionLimit: 10,
  host     : process.env.MYSQL_HOST,
  user     : process.env.MYSQL_USER,
  password : process.env.MYSQL_PW,
  database : process.env.MYSQL_DB
});

function getConn() {
  return pool.getConnection().disposer(function(connection) {
    pool.releaseConnection(connection);
  });
}

module.exports = getConn;

I added console log entries and I can see that it completes them...however it does not return anything and I end up with a connection error. I see that the data is fetched and Lambda just sits there without returning anything for 6 seconds. Below is the latest entry from cloud watch:

18:15:01 START RequestId: 195a7218-a516-11e6-b52d-5f028bb2bdf6 Version: $LATEST 18:15:01 2016-11-07T18:15:01.820Z 195a7218-a516-11e6-b52d-5f028bb2bdf6 found roles: 9 18:15:07 END RequestId: 195a7218-a516-11e6-b52d-5f028bb2bdf6 18:15:07 REPORT RequestId: 195a7218-a516-11e6-b52d-5f028bb2bdf6 Duration: 6002.14 ms Billed Duration: 6000 ms Memory Size: 1024 MB Max Memory Used: 18 MB 18:15:07 2016-11-07T18:15:07.468Z 195a7218-a516-11e6-b52d-5f028bb2bdf6 Task timed out after 6.00 seconds

Is there something that breaks when using Bluebird with Lambda?

2
node.jslambdapromisebluebirdserverless-framework

2 Answers

1
votes

Just a note about the accepted answer: It is not recommended to release a db connection using the finally block. In case something breaks in the lifecycle of the promise chain, there is a chance finally may not be called leading to resource leaks. This is documented in bluebird docs: http://bluebirdjs.com/docs/api/resource-management.html

0
votes

Bluebird definitely works.

I think there might be a problem with ending connection using disposer. I use postgresql promise library so can't really try with mysql but I rewritten it to use disposer and I get same timeout.

Try ending connection in your finally block.

db.getConnection()
  .then(doMyQuery)
  .catch(catchErrors)
  .finally(db.disposeConnection)

EDIT: Ok, actually releasing connections is bad in lambdas, you should be ending them. mysqljs docs say:

When you are done with a connection, just call connection.release() and the connection will return to the pool, ready to be used again by someone else.

You don't really want that. That's why you get a timeout. When your promise chain ends, the connection returns to the pool and WAITS to be used again, thus lambda timeouts since it's never ending.

Use connection.end() or connection.destroy()