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Quickstart Guide: Compose and Django
This Quick-start Guide will demonstrate how to use Compose to set up and run a simple Django/PostgreSQL app. Before starting, you'll need to have Compose installed.
Define the project
Start by setting up the three files you'll need to build the app. First, since
your app is going to run inside a Docker container containing all of its
dependencies, you'll need to define exactly what needs to be included in the
container. This is done using a file called Dockerfile. To begin with, the
Dockerfile consists of:
FROM python:2.7
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
ADD requirements.txt /code/
RUN pip install -r requirements.txt
ADD . /code/
This Dockerfile will define an image that is used to build a container that includes your application and has Python installed alongside all of your Python dependencies. For more information on how to write Dockerfiles, see the Docker user guide and the Dockerfile reference.
Second, you'll define your Python dependencies in a file called
requirements.txt:
Django
psycopg2
Finally, this is all tied together with a file called docker-compose.yml. It
describes the services that comprise your app (here, a web server and database),
which Docker images they use, how they link together, what volumes will be
mounted inside the containers, and what ports they expose.
db:
image: postgres
web:
build: .
command: python manage.py runserver 0.0.0.0:8000
volumes:
- .:/code
ports:
- "8000:8000"
links:
- db
See the docker-compose.yml reference for more information on how
this file works.
Build the project
You can now start a Django project with docker-compose run:
$ docker-compose run web django-admin.py startproject composeexample .
First, Compose will build an image for the web service using the Dockerfile.
It will then run django-admin.py startproject composeexample . inside a
container built using that image.
This will generate a Django app inside the current directory:
$ ls
Dockerfile docker-compose.yml composeexample manage.py requirements.txt
Connect the database
Now you need to set up the database connection. Replace the DATABASES = ...
definition in composeexample/settings.py to read:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'postgres',
'USER': 'postgres',
'HOST': 'db',
'PORT': 5432,
}
}
These settings are determined by the postgres Docker image specified in the Dockerfile.
Then, run docker-compose up:
Recreating myapp_db_1...
Recreating myapp_web_1...
Attaching to myapp_db_1, myapp_web_1
myapp_db_1 |
myapp_db_1 | PostgreSQL stand-alone backend 9.1.11
myapp_db_1 | 2014-01-27 12:17:03 UTC LOG: database system is ready to accept connections
myapp_db_1 | 2014-01-27 12:17:03 UTC LOG: autovacuum launcher started
myapp_web_1 | Validating models...
myapp_web_1 |
myapp_web_1 | 0 errors found
myapp_web_1 | January 27, 2014 - 12:12:40
myapp_web_1 | Django version 1.6.1, using settings 'composeexample.settings'
myapp_web_1 | Starting development server at http://0.0.0.0:8000/
myapp_web_1 | Quit the server with CONTROL-C.
Your Django app should nw be running at port 8000 on your Docker daemon. If you are using a Docker Machine VM, you can use the docker-machine ip MACHINE_NAME to get the IP address.
You can also run management commands with Docker. To set up your database, for
example, run docker-compose up and in another terminal run:
$ docker-compose run web python manage.py syncdb