docker-webhook

Simple python application to listen for GitHub webhook events and run scripts in response to push events. This is mostly useful as a part of a larger project that needs to reload itself on deploy events. The behavior of this image can be altered through the use of environment variables, the full list of which are included in a table below. The suggested way of using this image is through a docker-compose.yml setup. To illustrate this, read through the following scenario and code bits:

Let us imagine I have an application running with an nginx frontend and some kind of backend. I want this application to redeploy itself when it receives a push event from GitHub on either the branch master or release-1.0. To do so, I would first add configuration to the application's docker-compose.yml file similar to the following:

version: '2.1'
services:
    frontend:
        // blah blah blah...
    main_app:
        // blah blah blah...
    webhook:
        restart: unless-stopped
        image: staticfloat/docker-webhook
        volumes:
            # Mount this code into /code
            - ./:/code
            # Mount the docker socket
            - /var/run/docker.sock:/var/run/docker.sock
        environment:
            - WEBHOOK_SECRET=${WEBHOOK_SECRET}
            - WEBHOOK_HOOKS_DIR=/code/hooks
            - WEBHOOK_BRANCH_LIST=master
        expose:
            - 8000

This creates a webhook service that will listen for incoming webhook events on (docker-internal) port 8000. Note that I have left the WEBHOOK_SECRET as a variable even in the docker-compose.yml. This is because I have found it handy to encrypt these values in a separate .env file with git-crypt.

To route webhook events to the webhook image, I will add this snippet to my frontend nginx config:

    location /_webhook {
        proxy_pass http://webhook:8000/;
    }

Finally, within my application code, I will create a directory hooks and place executable files such as bash shell scripts that will run within there. In this case, I will put a deploy.sh file within that directory:

#!/bin/bash

cd /code
docker-compose build --pull && docker-compose up --build --remove-orphans -d

Commands such as bash, make, python and docker-compose are available within the staticfloat/docker-webhook image, but if you need something more complex than that, you will likely need to add them.

Significant environment variables:

Variable	Required	Effect
WEBHOOK_SECRET	YES	Defines the secret used for github hook verification
WEBHOOK_HOOKS_DIR	NO	Directory where hooks are stored, defaults to /app/hooks
WEBHOOK_BRANCH_LIST	NO	Comma-separated list of branches, defaults to master

Misc. information

There is also a /logs endpoint that will show the stdout and stderr of the last execution.