Auto-reloading of code changes with Django development in Docker with Gunicorn

Question

I'm using a Docker container for Django development, and the container runs Gunicorn with Nginx. I'd like code changes to auto-load, but the only way I can get them to load is by rebuilding with docker-compose (docker-compose build). The problem with "build" is that it re-runs all my pip installs.

I'm using the Gunicorn --reload flag, which is apparently supposed to do what I want. Here are my Docker config files:

## Dockerfile: FROM python:3.4.3 RUN mkdir /code WORKDIR /code ADD . /code/ RUN pip install -r /code/requirements/docker.txt  ## docker-compose.yml: web:   restart: always   build: .   expose:     - "8000"   links:     - postgres:postgres   volumes:     - /usr/src/app/static   env_file: .env   command: /usr/local/bin/gunicorn myapp.wsgi:application -w 2 -b :8000 --reload  nginx:   restart: always   build: ./config/nginx   ports:     - "80:80"   volumes:     - /www/static   volumes_from:     - web   links:     - web:web  postgres:   restart: always   image: postgres:latest   volumes:     - /var/lib/postgresql   ports:     - "5432:5432" 

I've tried some of the other Docker commands (docker-compose restart, docker-compose up), but the code won't refresh.

What am I missing?

Answer 1

Thanks to kikicarbonell, I looked into having a volume for my code, and after looking at the Docker Compose recommended Django setup, I added volumes: - .:/code to my web container in docker-compose.yml, and now any code changes I make automatically apply.

## docker-compose.yml: web:   restart: always   build: .   expose:     - "8000"   links:     - postgres:postgres   volumes:     - /usr/src/app/static     - .:/code   env_file: .env   command: /usr/local/bin/gunicorn myapp.wsgi:application -w 2 -b :8000 --reload 

Update: for a thorough example of using Gunicorn and Django with Docker, checkout this example project from Rackspace, which also shows how to use docker-machine to launch the setup on remote servers like Rackspace Cloud.

Caveat: currently, this method does not work when your code is stored locally and the docker host is remote (e.g., on a cloud provider like Digital Ocean or Rackspace). This also applies to virtual machines if your local file system is not mounted on the VM. Note that there are separate volume drivers (e.g., flocker), and there might be something out there to address this need. For now, the "fix" is to rsync/scp your files up to a directory on the remote docker host. Then, the --reload flag will auto-reload gunicorn after any scp/rsync. Update: If pushing code to remote docker host, I find it far easier to just rebuild the docker container (e.g., docker-compose build web && docker-compose up -d). This can be slower though than the rsync approach if your src folder is large.