dev-lambda

Provide AWS Lambda like functionality for local Node.js development purposes.

Purpose

Developing AWS lambda's isn't very hard but it would be nice to be able to serve them locally for rapidly testing changes, offline development, and intergration testing.

The System

• each lambda should be its own directory
• a parent directory contains all the lambdas to be served
• dev-lambdaprovides a simple REST API communicating in JSON
• the API can be used to list all available lambdas, simple metrics, and recent history of the output of each lambda
• the API can be used to pass event data and initiate lambdas
• the API provides a sync endpoint for each lambda for easier debugging

Getting Started

First copy the example lambda directory into the lambdas directory so we have something to see once the server is up.

Clone and Get Dependencies

git clone https://github.com/CoursePark/dev-lambda.git
cd dev-lambda
npm install

Use Example Worker

cp -r example-lambda lambdas/

Now we can kick off the server with Node.js, later we will do the same with a dockerizered version.

Straight Node.js

node lib/daemon.js

Now visit http://127.0.0.1:9961/ in your browser and you should see JSON saying something like:

{"example-lambda":{"config":{"name":"example-lambda","dirPath":"/Users/me/dev-lambda/lambdas/example-lambda","handler":"index.handler","maxMemory":128,"timeout":3}}}

So great, we can see that the example example-lambda is set up and ready. Lets run it, this is done by POSTing to http://127.0.0.1:9961/example-lambda.

using curl:

curl -X POST http://127.0.0.1:9961/example-lambda

or use something like the excellent Chrome App Postman

and should get something like, look for the Hello World!:

{"metrics":{"counts":{"total":1,"started":0,"done":1},"averageDuration":103},"history":[{"status":"done","started":"2015-11-18 04:53:46.165","updated":"2015-11-18 04:53:46.268","output":["2015-11-18 04:53:46.264: Hello World!\n","2015-11-18 04:53:46.265: event {}\n"],"completed":"2015-11-18 04:53:46.268","duration":103}],"config":{"name":"example-lambda","dirPath":"/Users/me/dev-lambda/lambdas/example-lambda","handler":"index.handler","maxMemory":128,"timeout":3}}

Now we just need the ability to pass event data into the lambda. This is accomplished by POSTing JSON as a request body and having a Content-Type: application/json header.

curl -H "Content-Type: application/json" -X POST -d '{"abc":"123"}' http://127.0.0.1:9961/sync/example-lambda

results in something like:

{"metrics":{"counts":{"total":2,"started":0,"done":2},"averageDuration":105},"history":[{"status":"done","started":"2015-11-18 05:02:39.006","updated":"2015-11-18 05:02:39.109","output":["2015-11-18 05:02:39.105: Hello World!\n","2015-11-18 05:02:39.107: event { abc: '123' }\n"],"completed":"2015-11-18 05:02:39.109","duration":103},{"status":"done","started":"2015-11-18 05:01:56.730","updated":"2015-11-18 05:01:56.837","output":["2015-11-18 05:01:56.833: Hello World!\n","2015-11-18 05:01:56.834: event {}\n"],"completed":"2015-11-18 05:01:56.837","duration":107}],"config":{"name":"example-lambda","dirPath":"/Users/me/dev-lambda/lambdas/example-lambda","handler":"index.handler","maxMemory":128,"timeout":3}}

Using Docker

docker build -t dev-lambda .

docker run -ti -p 9961:9961 -v /Users/me/my-lambdas/:/usr/src/app/lambdas dev-lambda