Quick and dirty local lambda development environment.

local-lambda.js

'use strict';

// To use - edit the options below and `node local-lambda.js`

// path to your lambda entry point
var app = require('./index.js');
// the handler you wish to test (you may only have one e.g. exports.handler)
var handler = app.handler;
// simulated max duration
var duration = 30000;
// the sample/mock event you'd like to use for testing
var mockEvent = require('./mock-event.json');

// TODO: CLI mockEvent to ease testing multiple environments
// TODO: implement maximum memory usage.  i seem to remember process.memoryUsage() being unreliable https://nodejs.org/api/process.html#process_process_memoryusage

// ==========================

var end = new Date().getTime() + duration;
var context = {
  awsRequestId: 'awsr-eque-stid-fake-9184', // e_e
  getRemainingTimeInMillis: function() {
    return Math.max(0, end - new Date().getTime());
  },
  succeed: function(obj) {
    console.log('Succeeded', obj);
    process.exit();
  },
  fail: function(err) {
    console.log('Failed', err);
    process.exit(1);
  },
  done: function(err, obj) {
    if (err) {
      context.fail(err);
    }
    else {
      context.succeed(obj);
    }
  },
};

handler(mockEvent, context);

package.sh

#!/usr/bin/env bash

cd $(dirname $0)

rm -f dist.zip
rm -fr node_modules

# lambda is currently 0.10.  i recommend using nvm with 0.12 since 
# i've found aws-sdk on node v0.10 problematic when running locally (for whatever reason)
# nvm use 0.12

# don't install devDeps
npm install --production

# optional. if some deps are es6 only, you can use this to transpile to something that'll work with lambda
# babel --plugins ../../scripts/build/node_modules/babel-plugin-transform-object-set-prototype-of-to-assign --presets ../../scripts/build/node_modules/babel-preset-es2015 node_modules/wreck -d node_modules/wreck
# sometimes that es6 transpiling isn't perfect
# node transpiling-patch.js

# finally create our lamabda bundle. only include what we explicitly want
zip -r dist.zip index.js config.js package.json node_modules/ lib/

s3-put-event-example.js

// this is json but i wanted comments.  the contents here would be 
// named "mock-event.json" as described above

// this is pulled from lambda's canned testing events

{
  "Records": [
    {
      "eventVersion": "2.0",
      "eventTime": "1970-01-01T00:00:00.000Z",
      "requestParameters": {
        "sourceIPAddress": "127.0.0.1"
      },
      "s3": {
        "configurationId": "testConfigRule",
        "object": {
          "eTag": "0123456789abcdef0123456789abcdef",
          "sequencer": "0A1B2C3D4E5F678901",
          "key": "HappyFace.jpg",
          "size": 1024
        },
        "bucket": {
          "arn": "arn:aws:s3:::mybucket",
          "name": "sourcebucket",
          "ownerIdentity": {
            "principalId": "EXAMPLE"
          }
        },
        "s3SchemaVersion": "1.0"
      },
      "responseElements": {
        "x-amz-id-2": "EXAMPLE123/5678abcdefghijklambdaisawesome/mnopqrstuvwxyzABCDEFGH",
        "x-amz-request-id": "EXAMPLE123456789"
      },
      "awsRegion": "us-east-1",
      "eventName": "ObjectCreated:Put",
      "userIdentity": {
        "principalId": "EXAMPLE"
      },
      "eventSource": "aws:s3"
    }
  ]
}

transpiling-patch.js

// example of a transpiling-patch.js; used in package.sh

// wreck and dependencies are all es6 and >= node 4.0 because of it
// whether or not we agree with that decision we must deal with it

// babel transpiling works for the most part except for one line. let's just str replace

var fs = require('fs');
var path = require('path');

var target = path.join(__dirname, 'node_modules/wreck/node_modules/boom/lib/index.js');

var data = fs.readFileSync(target).toString();
var patched = data.replace('}, null)', '}, {})');
fs.writeFileSync(target, patched);