A simple server for controlling GPIO pins on embedded devices

This is a tiny webserver designed to receive webhooks that control microcontrollers running gpio-webhook.

Configuration

The server can be configured via the following environment variables:

DEBUG - if set, extra output will be logged / generated. this will leak secrets to stdout
LISTEN_PORT - the TCP port to serve the app on. Default is 7200.
WEBHOOK_CONFIG_FILE - location of the webhook config. Defaults to ./webhooks.yaml.

The webhooks configuration file should be an array of entries with the following keys:

name - A human-readable name that explains the webhook's purpose.
path - The webhook will be served by the app at this path. Treat this as a secret value.
num_switches - the number of data points / indexes expected with each POST.
momentary_switches - an array of any indexes that refer to 'momentary' switches.
The value of these indexes will be reset to 0 after the next GET request to the webhook.

Build the server with:

make build

And run with:

./gpio-webhook-server

A dockerfile is also included, along with a sample docker-compose.yml demonstrating how the server might be run in a containerized environment.

Note that you SHOULD always run this service behind a TLS-encrypted proxy. Using plain http WILL expose your secrets.

To read the current webhook data, simply send a GET to the webhook URL, with the key parameter appropriately set. Example:

curl -x GET "https://example.com/WEBHOOK_PATH

To write data, send a POST to the same URL, with a json-formatted body in the following format:

[value0, value1, value2, ...]

Use a more robust secret than "the URL is hidden behind TLS." Maybe client-side x509 certs.