Webhooks

An example of how webhooks might be implemented as an integration point for a web application.

When I worked at Atlassian I headed up the effort to revamp the webhooks offering. This is a very simple example of a webhooks subsystem based on that experience. This is not a full-feature webhooks implementation. This is a quick-and-dirty spin-up to include in my portfolio of example creations when I apply for jobs.

Tech stack

• Python, Django, requests, boto3
• PostgreSQL
• ElasticMQ (In-memory message queue with an Amazon SQS-compatible interface. Runs stand-alone or embedded.)
• Docker, docker-compose

Architecture

A main web app exists and new webhooks functionality is added by creating a microservice.

Example usage

Install AWS boto3 dependency for producer script which simulates an event occuring in the main web app.

% pip3 install boto3

Start up the services.

% docker-compose up -d db mq
% docker-compose up web worker

Create a webhook definition using the API.

% http POST localhost:8000/webhooks/ url=http://10.0.2.2:7777
HTTP/1.1 200 OK
Content-Length: 78
Content-Type: application/json
Date: Mon, 28 Jun 2021 17:49:47 GMT
Referrer-Policy: same-origin
Server: WSGIServer/0.2 CPython/3.9.5
X-Content-Type-Options: nosniff
X-Frame-Options: DENY

[
    {
        "fields": {
            "url": "http://10.0.2.2:7777"
        },
        "model": "app.webhook",
        "pk": 7
    }
]

Add 10.0.2.2 as a loopback address on your Mac.

% sudo ifconfig lo0 alias 10.0.2.2

Start the simple "third-pary" webhook consumer at the same URL used when defining the webhook configuration in the microservice. This consumer will just print out the payload of any webhooks it receives.

% python3 consumer.py

Simulate an event occuring in the main web app by running the producer script.

% python3 producer.py

Note the printed messages in the consumer terminal.

{"event": "Hello webhooks world"}