django_discovery 0.0.3

Docker service discovery for Django

This project provides a simple workflow for registering services in Django. It is highly opinionated and makes a lot of assumptions.

Goal

When developing a Django application, you often need external services such as a database, a key-value store, a message broker, etc. etc. I prefer to use Docker and Docker-Compose to have those services running when I develop my application.

django-discovery makes it easy to connect to those services, as long as you follow a specific workflow:

• Development is done on your own machine, with the services running under Docker;

• Testing is done by running both the services and the application using Docker Compose;

• The production environment provides an SRV-lookup capable DNS. Examples are:

  • Running everything under Kubernetes

  • Running everything on Docker, configured to use an SRV-capable DNS such as Consul

Requirements

django-discovery requires Python 3 and Django 1.8 because we live in modern times.

Quickstart

The following example assumes a Django application that requires a MySQL database. Add the following to your settings.py:

from discovery import services

db = services.register('my_db', 'mysql', secrets=['mysql_user', 'mysql_database', 'mysql_password'])

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': db.secrets['mysql_database'],
        'USER': db.secrets['mysql_user'],
        'PASSWORD': db.secrets['mysql_password'],
        'HOST': db.host,
        'PORT': db.port,
    }
}

DEBUG = services.debug_mode

You can now run your application on localhost with your database under docker using the following docker-compose.yml:

my_db:
    image: mysql:5.6
    ports:
        - ":3306"
    environment:
        MYSQL_ROOT_PASSWORD: supersecret
        MYSQL_DATABASE: database_name
        MYSQL_USER: database_user
        MYSQL_PASSWORD: alsosecret

You can also run your application in its entirety in docker, using for example the following docker-compose file:

database:
    image: mysql:5.6
    environment:
        MYSQL_ROOT_PASSWORD: supersecret
        MYSQL_DATABASE: database_name
        MYSQL_USER: database_user
        MYSQL_PASSWORD: alsosecret

application:
    build: .
    links:
        - database:my_db
    ports:
        - "80:8080"
    env:
        DISCOVERY_MODE: env

And still using the same settings.py, you can even run your application under Kubernetes using the following definitions:

apiVersion: v1
kind: Service
metadata:
  name: my_db
spec:
  ports:
    - protocol: tcp
      port: 3306

apiVersion: v1
kind: Endpoints
metadata:
  name: my_db
subsets:
  - addresses:
    - ip: 1.2.3.4
  - ports:
    - port: 3306

apiVersion: v1
kind: Pod
metadata:
  name: my_application
  namespace: my_namespace
spec:
  containers:
     - name: my_application
       image: my/docker-image
       volumeMounts:
         - name: db_secrets
           mountPath: /etc/secrets/my_db
           readOnly: true
  volumes:
    - name: db_secrets
      secret:
        mysql_database: some_name
        mysql_user: some_user
        mysql_password: secret_password

Full Documentation

Working on it…

License

This project is licensed under the MIT license.