Using Ngrok to connect to local PostgreSQL from AWS Lamba

Question

I'm trying to use node-postgres (PG) to connect to my localhost PostgreSQL database running on port 5432. To do this, I've setup ngrok to tunnel my request.

./ngrok tcp 5432

The code below works when running locally (even when tunneling using ngrok). It also works on lambda when I connect to an external database - in my case hosted by Heroku.

'use strict';

const PG = require('pg');

// These credentials work locally
var credentials = {
    user: 'MyUsername',
    host: 'tcp://0.tcp.ngrok.io',
    database: 'MyDatabase',
    password: 'MyPassword',
    port: '12829',
    ssl: true
};

const pool = new PG.Pool(credentials);

const connectionPromise = function(){
    return new Promise(function (resolve, reject) {
        pool.connect(function (err, client, done) {
            if(err) console.log(err);
            err ? reject(err) : resolve({
                client: client,
                done: done
            })
        })
    });
};


exports.handler = Handler;

function Handler(event, context, callback) {
    context.callbackWaitsForEmptyEventLoop = false;

    console.log("Calling handler in Lambda");
    return connectionPromise().then(function (conn) {
        console.log("Success");
        callback(null);
    }).catch(function (err) {
        console.log("Error");
        callback(err);
    });
};

// Uncomment this code to run locally.
// Handler(null, {}, function(){
//     console.log("Exiting");
//     process.exit();
// });

However, when I attempt to use node-postgres + Ngrok to connect to my localhost database via Lambda ...

Error: getaddrinfo ENOTFOUND tcp://0.tcp.ngrok.io tcp://0.tcp.ngrok.io:12829

Full Error Message

START RequestId: 3ac634ef-310e-41ab-b20f-14c86271b5d7 Version: $LATEST 2019-01-21T16:14:27.020Z 3ac634ef-310e-41ab-b20f-14c86271b5d7 Calling handler in Lambda 2019-01-21T16:14:27.117Z 3ac634ef-310e-41ab-b20f-14c86271b5d7 { Error: getaddrinfo ENOTFOUND tcp://0.tcp.ngrok.io tcp://0.tcp.ngrok.io:12829 at errnoException (dns.js:50:10) at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:92:26) code: 'ENOTFOUND', errno: 'ENOTFOUND', syscall: 'getaddrinfo',
hostname: 'tcp://0.tcp.ngrok.io', host: 'tcp://0.tcp.ngrok.io',
port: 12829 } 2019-01-21T16:14:27.118Z 3ac634ef-310e-41ab-b20f-14c86271b5d7 Error 2019-01-21T16:14:27.155Z 3ac634ef-310e-41ab-b20f-14c86271b5d7 {"errorMessage":"getaddrinfo ENOTFOUND tcp://0.tcp.ngrok.io tcp://0.tcp.ngrok.io:12829","errorType":"Error","stackTrace":["errnoException (dns.js:50:10)","GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:92:26)"]} END RequestId: 3ac634ef-310e-41ab-b20f-14c86271b5d7 REPORT RequestId: 3ac634ef-310e-41ab-b20f-14c86271b5d7 Duration: 136.26 ms Billed Duration: 200 ms Memory Size: 128 MB Max Memory Used: 23 MB

Is lambda blocking ngrok?

Answer 1

Remove tcp:// from ngrok hostname:

var credentials = {
    user: 'MyUsername',
    host: '0.tcp.ngrok.io',
    database: 'MyDatabase',
    password: 'MyPassword',
    port: '12829',
    ssl: true
};