detectordag

Power outage detector made with ♥ by a dag.

Introduction

This is an IoT project that uses 'dags' to monitor the power whilst you are away from home. You can read the motivation on my blog.

The 'dags' (RaspberryPi-Zero + a small UPS) report status updates to a serverless application hosted on AWS. Status updates are communicated to end-users via email, or may be checked asynchronously at detectordag.tk.

Architecture

Broadly the system divides in two:

• Edge devices
• 'the cloud'

An edge device is a RaspberryPi-Zero device paired with the UPS-Lite uninterruptable power supply and an LTE dongle for connectivity. Software is deployed via BalenaCloud, along with other fleet management tasks.

The cloud sub-system is a collection of serverless entities on AWS: including IoT Core, Lambda, API gateway, SQS. The Cloudformation designer, when supplied this project's template.yml gives this spaghetti mess:

The following list gives an overview of the subdirectories of this project:

• api/: contains a JSON REST API written in Go deployed as an AWS lambda
• consumer/: AWS Lambda written in Go for processing 'power status changed' MQTT events
• connection/: contains two further AWS IoT lambdas to debounce connection status events
• edge/: Python application to run on the Raspberry Pi
• frontend/: Vue.js frontend, deployed at detectordag.tk

Installation

This project uses a few different tools:

Mage

The project generally uses mage for project build commands, which retrospectively was a pain-in-the-arse, but oh well...

go get -u -d github.com/magefile/mage

go run bootstrap.go

AWS CLI

# Install the general AWS CLI
brew install awscli
# Install the SAM CLI
brew tap aws/tap
brew install aws-sam-cli

You will need to download credentials and save them to ~/.aws/credentials to interact with AWS.

Provisioning

Cloud resources

Most AWS resources are provisioned using the CloudFormation template.yml.

# Build the lambda functions
sam build
# Deploy to AWS
sam deploy

Provisioning 'dags'

New devices need to be provisioned on a device-by-device basis. A handy mage command is provided in order to provision a 'thing' on AWS matching a device on BalenaCloud, obtaining a build image ready to be flashed to an SD card.

# Provision a device
env DDAG_DEVICE_ID=3cf9f9b7-b7d2-46db-9e6b-5f80fdfe8aa0 \
    DDAG_DEVICE_NAME=second \
    DAG_ACCOUNT_ID=aac45d02-c97d-442c-8431-336d578fdcf7 \
    mage -v provisionDevice

Some notes:

• IoT things should be of Thing Type "detectordag" in order to ensure they have the expected attributes (e.g. account ID)
• IoT things should be a member of Thing Group "detectordag" in order to give them the correct permissions for updating their shadow