Deploy a Django App with Docker

In a previous post I deployed a Flask app with Docker. This time around I wanted to see if it was any different to host a Django app. It turns out that it wasn’t that much different.

Installation

First, install the Docker using their installation instructions for you platform. I am on a mac, so I installed the DMG from their site, and then from the command line ran,

brew install docker

The Docker daemon doesn’t start automatically after downloading it, so you need to find it, and double-click on it to start it up. Once it’s running, you can execute docker commands from the command line.

Setup

Create and cd into a directory called example/.

mkdir example
cd example

Start a Virtual Environment on your Host

Creating a virtual environment for your application will help you install and import only what is needed for your application. Once it is time to deploy, just freeze your requirements into a requirements.txt document, and you’ll have a snapshot of what your application needs in order to run.

If you’re using Python3, from the example/ directory you can say,

python3 -m venv venv
source venv/bin/activate

Now you should see a venv/ directory inside your example/ directory. Now install Django by saying,

python -m pip install django

Once that is done, create a requirements document,

pip freeze > requirements.txt

This should create requirements.txt at the root of the example/ directory.

Creating a Simple Django App

I used Django’s startproject command to get started. This creates a directory for your project called app/, with another directory inside that is also called app/. The outer app/ directory isn’t used anywhere internally, so you can name it whatever you like.

django-admin startproject app

Create a Dockerfile

I created a Dockerfile to install the requirements, copy the application over, and start the server. Note, I am currently in a directory called “example”. My Dockerfile is in the root of that directory. The app/ directory, containing my Flask app, app.py, is also in the “example” directory, beside the Dockerfile.

# ~/example/Dockerfile

FROM python:3.7.0-alpine3.8

WORKDIR /usr/src/app
COPY requirements.txt ./
RUN pip install -r requirements.txt
COPY app/* ./

EXPOSE 8000
CMD ["python", "manage.py", "runserver", "0.0.0.0:8000"]

Build and Run Docker

Now, we should be able to build an image by saying:

docker build -t hello-world

And then we should be able to run that image in a container by saying:

docker run -p 8000:8000 hello-world

Now, if we visit localhost:8000 we should see the default Django splash page.

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