Django, Postgres, Gunicorn, Nginx with Docker (Part-1)

Updated on May 31, 2023, 10:45 a.m., by: sagar

**Prerequisites**

First, ensure the following is installed on you machine:

*   [Python](https://www.python.org/) 3.7 or higher(I've used python 3.8.9)
*   Python [pip](https://pypi.org/project/pip/)
*   [Git](https://git-scm.com/) and a [GitHub](https://github.com/) account
*   [Docker](https://www.docker.com/) and [docker-compose](https://docs.docker.com/compose/install/)

Let's jump directly to dockerization of django web application. I'm sure you have django project set-up on your system.

Docker

After installation of docker, add a _Dockerfile_ to the root directory of you project:

FROM python:3.8.9-alpine
    
    WORKDIR /app
    
    ENV PYTHONDONTWRITEBYTECODE 1
    ENV PYTHONNUNBUFFERED 1
    
    RUN pip install --upgrade pip
    COPY ./requirements.txt .
    
    RUN pip install -r requirements.txt
    
    COPY . .

Here, we used alpine-based docker image for python 3.8.9. Then we set two environmental variables:

1.  PYTHONDONTWRITEBYTECODE (which prevents writing pyc files)
2.  PYTHONUNBUFFERED (which prevents buffering stdout and stderr)

And, we updated pip version and copied _requirements.txt_ file to working directory, and installed requirements. After that we finally codpied our project to working directory(/app).

Now, create a docker-compose.yml file to the project root and add services:

version: '3.5'
    
    services:
        app:
            build: .
            command: python manage.py runserver 0.0.0.0:8000
            volumes:
                - static_data:/vol/web
            ports:
                - "8000:8000"
            restart: always
            env_file:
                - ./.env

Create .env file at the root (same directory containing docker-compose.yml) and edit as:

DEBUG=1
    SECRET_KEY=foo
    DJANGO_ALLOWED_HOSTS=localhost 127.0.0.1 [::]

Update DEBUG, ALLOWED\_HOSTS variables in _settings.py_:

DEBUG = int(os.environ.get("DEBUG", default=0))
    
    # 'DJANGO_ALLOWED_HOSTS' should be a single string of hosts with a space between each.
    # For example: 'DJANGO_ALLOWED_HOSTS=localhost 127.0.0.1 [::1]'
    ALLOWED_HOSTS = os.environ.get("DJANGO_ALLOWED_HOSTS").split(" ")

In docker-compose file, _build: ._ means it will build image from the root Dockerfile we have created before.

Now, build the image:

$ docker-compose build

Use sudo if needed.

Run the container once image is built:

$ docker-compose up -d

_\-d_ is used to run process in background.

If it this doesn't work check errors  with **_docker-compose logs -f_** command.

**Postgres**

Add new service to the _docker-compose.yml_ file, and update django database settings, with [Psycopg2](http://initd.org/psycopg/).lets add new service named as app-db:

version: '3.5'
    
    services:
        app:
            build: .
            command: python manage.py runserver 0.0.0.0:8000
            volumes:
                - static_data:/vol/web
            ports:
                - "8000:8000"
            restart: always
            env_file:
                - ./.env
            depends_on:
                - app-db
    
        app-db:
            image: postgres:12-alpine
            ports:
                - "5432:5432"
            restart: always
            volumes:
                - postgres_data:/var/lib/postgresql/data:rw
            env_file:
                - .env
    # you can also use environmental variables directly as following:
    #(remember variables for postgres should be named exactly as given below)
    #        environment:
    #            - POSTGRES_HOST_AUTH_METHOD=trust
    #            - POSTGRES_USER:sagar
    #            - POSTGRES_PASSWORD:********
    #            - POSTGRES_DB:portfolio_db
    #            - TZ:Asia/Kathmandu

We will just use the official Postgres docker image and postgres\_data is the persistent data volume within docker. It should suffice.

DEBUG=1
    DJANGO_ALLOWED_HOSTS=localhost 127.0.0.1 [::1]
    POSTGRES_HOST_AUTH_METHOD=trust
    POSTGRES_USER=sagar
    POSTGRES_PASSWORD=********
    POSTGRES_DB=portfolio_db
    POSTGRES_HOST=app-db
    POSTGRES_PORT=5432

Update the DATABASES dict in settings.py:

DATABASES = {
        'default': {
            'ENGINE': os.environ.get("DB_ENGINE", "django.db.backends.sqlite3"),
            'NAME': os.environ.get("POSTGRES_DB", os.path.join(BASE_DIR, "db.sqlite3")),
            'USER': os.environ.get("POSTGRES_USER", "default_user"),
            'PASSWORD': os.environ.get("POSTGRES_PASSWORD", "default_password"),
            'HOST': os.environ.get("POSTGRES_HOST", "localhost"),
            'PORT': os.environ.get("POSTGRES_PORT", "5432"),
    
        }
    }

Here, the database is configured based on the environment variables that we just defined. Take note of the default values. Update the Dockerfile to install the appropriate packages required for Psycopg2:

From python:3.8.9-alpine
    
    WORKDIR /app
    
    PYTHONDONTWRITEBYTECODE 1
    ENV PYTHONNUNBUFFERED 1
    
    #psycopg2 dependencies installation
    RUN apk update
    RUN apk add postgresql-dev gcc python3-dev musl-dev libc-dev linux-headers
    
    RUN pip install --upgrade pip
    COPY ./requirements.txt .
    
    RUN pip install -r requirements.txt
    
    COPY . .

Add Psycopg2 to _requirements.txt_. Make sure everytime you install packages, they are added to requirements.txt file. (_pip freeze > requirements.txt_)

Build the new image with two services:

$ docker-compose up -d --build

Then run the migrations:

$ docker-compose exec app python manage.py migrate --noinput

Operations to perform:
      Apply all migrations: admin, auth, blogs, contenttypes, django_summernote, portfolio, sessions, works
    Running migrations:
      Applying contenttypes.0001_initial... OK
      Applying auth.0001_initial... OK
      Applying admin.0001_initial... OK
      Applying admin.0002_logentry_remove_auto_add... OK
      Applying admin.0003_logentry_add_action_flag_choices... OK
      Applying contenttypes.0002_remove_content_type_name... OK
      Applying auth.0002_alter_permission_name_max_length... OK
      Applying auth.0003_alter_user_email_max_length... OK
      Applying auth.0004_alter_user_username_opts... OK
      Applying auth.0005_alter_user_last_login_null... OK
      Applying auth.0006_require_contenttypes_0002... OK
      Applying auth.0007_alter_validators_add_error_messages... OK
      Applying auth.0008_alter_user_username_max_length... OK
      Applying auth.0009_alter_user_last_name_max_length... OK
      Applying auth.0010_alter_group_name_max_length... OK
      Applying auth.0011_update_proxy_permissions... OK
      Applying blogs.0001_initial... OK
      Applying django_summernote.0001_initial... OK
      Applying django_summernote.0002_update-help_text... OK
      Applying portfolio.0001_initial... OK
      Applying sessions.0001_initial... OK
      Applying works.0001_initial... OK
      Applying works.0002_auto_20200325_1330... OK
      Applying works.0003_auto_20200325_1411... OK
      Applying works.0004_auto_20200325_1413... OK
      Applying works.0005_auto_20200325_1417... OK
      Applying works.0006_remove_work_image... OK
      Applying works.0007_work_image... OK

If any error, run **_docker-compose down -v_** to remove the volumes along with the containers. Then re-build and run migrations.

Ensure datavase tables are created:

$ docker-compose exec app-db psql --username=user --dbname=portfolio_db

#!/bin/sh
    
    if [ "$DATABASE" = "postgres" ]
    then
        echo "Waiting for postgres..."
    
        while ! nc -z "$POSTGRES_HOST" "$POSTGRES_PORT"; do
          sleep 0.1
        done
    
        echo "PostgreSQL started"
    fi
    
    # It's okay to run following two, flush and migrate commands on development mode(when debug mode is on) but not recommended
    # for production:
    
    # python manage.py flush --no-input
    # python manage.py migrate
    
    
    exec "$@"

Update Dockerfile with file permissions, and also add DATABASE variable to .env file.

From python:3.8.9-alpine
    
    WORKDIR /app
    
    PYTHONDONTWRITEBYTECODE 1
    ENV PYTHONNUNBUFFERED 1
    
    #psycopg2 dependencies installation
    RUN apk update
    RUN apk add postgresql-dev gcc python3-dev musl-dev libc-dev linux-headers
    
    RUN pip install --upgrade pip
    COPY ./requirements.txt .
    
    RUN pip install -r requirements.txt
    
    COPY . .
    COPY ./scripts /scripts
    
    RUN chmod +x /scripts/*
    
    RUN mkdir -p /vol/web/media
    RUN mkdir -p /vol/web/static
    
    RUN chmod -R 755 /vol/web
    
    ENTRYPOINT ["/scripts/entrypoint.sh"]

Edit .env file:

DEBUG=1
    DJANGO_ALLOWED_HOSTS=localhost 127.0.0.1 [::1]
    POSTGRES_HOST_AUTH_METHOD=trust
    POSTGRES_USER=user
    POSTGRES_PASSWORD=password
    POSTGRES_DB=portfolio_db
    POSTGRES_HOST=app-db #from docker-compose
    POSTGRES_PORT=5432
    DATABASE=postgres

Now, re-build, run and try http://localhost:8000/

Next: [Django, Postgres, Gunicorn, Nginx with Docker (Part-2)](https://budhathokisagar.com.np/blogs/5/)

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1 comment

Joseph

Great tutorial ! But not for beginner though.

June 4, 2021, 2:09 p.m.

Django, Postgres, Gunicorn, Nginx with Docker (Part-1)

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