Local Development with Docker

stefan foulis

docker-compose up - and we’re running!

What is docker? What are the benefits?

• (sort of) like a VM (lxc) but much more efficient
• great tools for building and sharing app envs
• dev/prod parity
• image is like a template - snapshot of VM
• container - an instance of an image - running app
• registry - store/share images

Basic Docker Concerts

• docker push/pull
• hub.docker.com has various images ready to go - redis, django, postgres
• images would in layers
  • debian 8
  • python 3.4
  • django (python 3)
  • mysite v1
• docker file

FROM django:python3-onbuild
RUN apt-get ...
RUN mkdir
WORKDIR ...
COPY localfs to docker

Create docker-ised django project

docker build -t mydjangoimage
docker run ... django-admin.py startproject mysite .
docker run ... python manage.py runserver 0.0.0.0:8000

django-compose

• cmd line tool that runs yaml file describing stack

yaml example

web:
  build: .
  volumes:
   - .:/usr/src/app
  ports:
  links:
    # to other images below
  env:
    # set environment variables

postgres:
  ...

redis:
  ...

• run commands in container - including bash
• need to rebuild occasionally - new dependencies
• pdb is hard - docker-compose run - then get an interactive console
• or docker exec ... /bin/bash - then run ps ...

nice urls with proxy

• docker - nginx proxy - reverse proxy for docker, nice magic for real URLs
• ssh termination ...
• much faster than vagrant
• can mount directories from outside the container into the container, eg for postgres data store