hapttic

What is this good for?

• You want to run some code in response to a webhook, like a github push.
• You have some code on your Raspberry Pi that you want to run from work (great in combination with ngrok).
• That's pretty much it.

How does it work?

Hapttic listens for incoming HTTP connections. When it receives a connection, it dumps all relevant data (headers, path, parameters, the body and other stuff) into a JSON object and calls a bash script with this object as its parameters.

Isn't this just a reinvention of CGI?

The basic idea is pretty similar. The main advantage of hapttic is ease of setup with a simple Docker image that lets you quickly connect a shell script to a http endpoint.

Show me an example

First, create a request handler at ~/hapttic_request_handler.sh:

echo $1

Then run the following command to spin up the docker container that runs hapttic:

docker run --rm -p 8080:8080 -v ~/hapttic_request_handler.sh:/hapttic_request_handler.sh --name hapttic jsoendermann/hapttic -file "/hapttic_request_handler.sh"

Finally, run open http://localhost:8080 to see the output of your script.

Show me a more realistic example

REQUEST=$1
SECRET_TOKEN=$(jq -r '.Header."X-My-Secret"[0]' <(echo $REQUEST))

if [[ "$SECRET_TOKEN" != "SECRET" ]]; then
  echo "Incorrect secret token"
  exit -1
fi

curl https://www.example.com/api/call/in/response/to/webhook

This request handling script can be run with curl -H "X-My-Secret: SECRET" http://localhost:8080

The jsoendermann/hapttic Dockerfile includes jq and curl, if you need any other command in your request handling script, you should create your own image.

The Request JSON object

The JSON object your request handling script gets called with is a subset of Go's http.Request. It's defined in hapttic.go as marshallableRequest. For documentation on http.Request, see the official net/http page.

SSL Support

You can add encryption by putting an nginx proxy in front of it with a docker-compose file like so:

version: '3'

volumes:
  vhost:
  html:

services:
  nginx-proxy:
    restart: always
    image: jwilder/nginx-proxy
    ports:
      - 80:80
      - 443:443
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro
      - /var/certs:/etc/nginx/certs:ro
      - vhost:/etc/nginx/vhost.d
      - html:/usr/share/nginx/html
    labels:
      - "com.github.jrcs.letsencrypt_nginx_proxy_companion.nginx_proxy=true"

  letsencrypt-nginx-proxy-companion:
    restart: always
    image: jrcs/letsencrypt-nginx-proxy-companion
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
      - /var/certs:/etc/nginx/certs:rw
      - vhost:/etc/nginx/vhost.d
      - html:/usr/share/nginx/html

  hapttic:
    restart: always
    image: jsoendermann/hapttic
    environment:
      - VIRTUAL_HOST=hapttic.your.domain.com                                # Replace this
      - LETSENCRYPT_HOST=hapttic.your.domain.com                            # Replace this
      - [email protected]                                # Replace this
    volumes:
      - /my-request-handler.sh:/hapttic_request_handler.sh                  # Replace this
    command: ["-file", "/hapttic_request_handler.sh"]
    depends_on:
      - nginx-proxy
      - letsencrypt-nginx-proxy-companion