Infra as Code for AWS IoT Greengrass

Greengo: a tool, and a starter boilerplate project to bring up (and clean-up!) AWS Greengrass setup for play and profit. If you followed the GreenGrass Getting Started Guide, here you find it automated, as code.

Describe your Greengrass group in group.yaml, write Lambda functions and device clients, provision Greengrass Core in Vagrant VM, deploy, and clean up.

Inspired by aws-iot-elf (Extremely Low Friction) and aws-greengrass-group-setup.

Pre-requisits

A computer with Linux/MacOS, Python, git (dah!)
Vagrant with VirtualBox
AWS CLI installed and configured. Consider using named profiles.

Set it Up

Install greengo from PyPI:

$ pip install greengo

Manually [*] download GreenGrassCore binary and place it in the ./downloads directory. Sign in to the AWS Management Console, navigate to the AWS IoT console, and download the AWS Greengrass Core Software from [Software section](https://us-west-2.console.aws.amazon.com/iotv2/home?region=us-west-2#/ software/greengrass). Yeah, manual sucks... I will automate it later. Or, submit your PR!

Play

Create GreenGrass Group definition in AWS

Fancy yourself with the group definitions in group.yaml, and run greengo:
```
$ greengo create
```
When runs with no errors, it creates all greengrass group artefacts on AWS and places certificates and config.json for GreenGrass Core in ./certs and ./config for Vagrant to use in provisioning on next step.
Provision VM with GreenGrass Core with Vagrant
```
$ vagrant up
```
Deploy Greengrass Group to the Core on the VM.
```
$ greengo deploy
```
Check that everything works - see the "Check" section below.
Profit !

Work on it: create, change or remove Lambda functions, subscriptions, resources, and then update Greengrass.
```
$ greengo update
```
Apply your changes by deploying it again:
```
$ greengo deploy
```
Clean-up when done playing.

Remove the group definitions on AWS:
```
$ greengo remove
```
Ditch the Vagrant VM:
```
$ vagrant destroy
```

For any of the above commands you may specify a different yaml file using

$ greengo --config_file <name>.yaml <command>

where <name> is the name of your yaml and <command> is whatever you wish to run

NOTE: If you want to create a new group but keep the Greengrass Core in the same Vagrant VM, you must update it with newly generated certificates and config.json file before deploying the group, and also reset deployment by getting the deployments/group/group.json back to virgin.

To do it: login to the Greengrass Vagrant VM and run /vagrant/scripts/update_ggc.sh on the Vagrant VM.

Details

Check the deployment

How to be sure ~~everything~~ something works? Follow this:

Create greengrass group in AWS IoT: greengo create.
Prepare GGC on the VM: update certificates, reset group.json, restart the greengrassd.
Deploy with greengo deploy. Check:
- Check the deployment status, should be 'Success'
Explore Greengrass Core on your vagrant VM.
- Login to Vagrant VM. You should nkow Vagrant but for the off case: vagrant ssh.
- Check the GGC logs runtime.log and python_runtime.log under /greengrass/ggc/var/log/system. Runtime log should have a line about starting your lambda, or an error why the funtion is not started. In many cases (like not enough memory for Lambda), the deployment is 'Success' but the function fails to start. The errors can only be seen in the runtime.log. If the function starts successfully, runtime.log will contain a message like
```
[2018-03-31T08:48:40.57Z][INFO]-Starting worker arn:aws:lambda:us-west-2:0000000000:function:GreengrassHelloWorld:12
```
- Find and check your own Lambda log under /greengrass/ggc/var/log/system.
- Check the greengrassd process: ps aux | grep greengrassd. Depending on deployment you might have several processes.
In AWS console, check the MQTT topic with IoT MQTT Test page:
```
REGION=`aws configure get region`; open https://$REGION.console.aws.amazon.com/iot/home?region=$REGION#/test
```
Subscribe to the topic (e.g., hello/world), see the messages sent by the Greengrass Lambda function.

When something goes wrong

At this time greengo is just a prototype, a work-in-progress. Therefore it's not if but when somethings throws out, leaving the setup in half-deployed, and you gotta pick up the pieces. Remember:

You are still not worse off doing this manually: you at least have all the ARN and Id of all resources to clean-up.
DON'T DELETE .gg/gg_state.json file: it contains references to everything you need to delete. Copy it somewhere and use the Id and Arn of created resources to clean up the pieces.
Do what it takes to roll forward - if you're close to successful deployment, or roll-back - to clean things up and start from scratch.

Please pay forward: PR a patch to whatever broke for you to prevent it from happening again.

Development

Clone the project, set up your environment, install dependencies and setup greengo CLI in dev mode:

$ git clone https://github.com/dzimine/greengo.git
$ cd greengo
$ virtualenv venv

$ . venv/bin/activate
$ pip install -r requirements.txt
$ pip install -e .

Run the unit tests:

pytest -s