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287 lines
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287 lines
10 KiB
Markdown
# Quickstart: Compose and Django
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This quick-start guide demonstrates how to use Docker Compose to set up and run a simple Django/PostgreSQL app. Before starting,
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[install Compose](https://docs.docker.com/compose/install/).
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## Define the project components
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For this project, you need to create a Dockerfile, a Python dependencies file,
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and a `docker-compose.yml` file. (You can use either a `.yml` or `.yaml` extension for this file.)
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1. Create an empty project directory.
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You can name the directory something easy for you to remember. This directory is the context for your application image. The directory should only contain resources to build that image.
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2. Create a new file called `Dockerfile` in your project directory.
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The Dockerfile defines an application's image content via one or more build
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commands that configure that image. Once built, you can run the image in a
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container. For more information on `Dockerfile`, see the [Docker user guide](https://docs.docker.com/get-started/)
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and the [Dockerfile reference](https://docs.docker.com/engine/reference/builder/).
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3. Add the following content to the `Dockerfile`.
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```dockerfile
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# syntax=docker/dockerfile:1
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FROM python:3
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ENV PYTHONDONTWRITEBYTECODE=1
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ENV PYTHONUNBUFFERED=1
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WORKDIR /code
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COPY requirements.txt /code/
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RUN pip install -r requirements.txt
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COPY . /code/
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```
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This `Dockerfile` starts with a [Python 3 parent image](https://hub.docker.com/r/library/python/tags/3/).
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The parent image is modified by adding a new `code` directory. The parent image is further modified
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by installing the Python requirements defined in the `requirements.txt` file.
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4. Save and close the `Dockerfile`.
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5. Create a `requirements.txt` in your project directory.
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This file is used by the `RUN pip install -r requirements.txt` command in your `Dockerfile`.
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6. Add the required software in the file.
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```python
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Django>=3.0,<4.0
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psycopg2>=2.8
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```
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7. Save and close the `requirements.txt` file.
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8. Create a file called `docker-compose.yml` in your project directory.
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The `docker-compose.yml` file describes the services that make your app. In
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this example those services are a web server and database. The compose file
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also describes which Docker images these services use, how they link
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together, any volumes they might need to be mounted inside the containers.
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Finally, the `docker-compose.yml` file describes which ports these services
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expose. See the [`docker-compose.yml` reference](https://docs.docker.com/compose/compose-file/) for more
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information on how this file works.
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9. Add the following configuration to the file.
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```yaml
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services:
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db:
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image: postgres
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volumes:
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- ./data/db:/var/lib/postgresql/data
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environment:
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- POSTGRES_DB=postgres
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- POSTGRES_USER=postgres
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- POSTGRES_PASSWORD=postgres
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web:
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build: .
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command: python manage.py runserver 0.0.0.0:8000
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volumes:
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- .:/code
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ports:
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- "8000:8000"
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environment:
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- POSTGRES_NAME=postgres
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- POSTGRES_USER=postgres
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- POSTGRES_PASSWORD=postgres
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depends_on:
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- db
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```
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This file defines two services: The `db` service and the `web` service.
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> Note:
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>
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> This uses the build in development server to run your application
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> on port 8000. Do not use this in a production environment. For more
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> information, see [Django documentation](https://docs.djangoproject.com/en/3.1/intro/tutorial01/#the-development-server){: target="_blank" rel="noopener" class="_”}.
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10. Save and close the `docker-compose.yml` file.
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## Create a Django project
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In this step, you create a Django starter project by building the image from the build context defined in the previous procedure.
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1. Change to the root of your project directory.
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2. Create the Django project by running the [docker compose run](https://docs.docker.com/engine/reference/commandline/compose_run/)
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command as follows.
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```console
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sudo docker compose run web django-admin startproject composeexample .
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```
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This instructs Compose to run `django-admin startproject composeexample`
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in a container, using the `web` service's image and configuration. Because
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the `web` image doesn't exist yet, Compose builds it from the current
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directory, as specified by the `build: .` line in `docker-compose.yml`.
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Once the `web` service image is built, Compose runs it and executes the
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`django-admin startproject` command in the container. This command
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instructs Django to create a set of files and directories representing a
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Django project.
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3. After the `docker compose` command completes, list the contents of your project.
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```console
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$ ls -l
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drwxr-xr-x 2 root root composeexample
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drwxr-xr-x 3 root root data
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-rw-rw-r-- 1 user user docker-compose.yml
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-rw-rw-r-- 1 user user Dockerfile
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-rwxr-xr-x 1 root root manage.py
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-rw-rw-r-- 1 user user requirements.txt
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```
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If you are running Docker on Linux, the files `django-admin` created are
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owned by root. This happens because the container runs as the root user.
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Change the ownership of the new files.
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Do not change the permission of the data folder where Postgres has its file, otherwise Postgres will not be able to start due to permission issues.
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```console
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sudo chown -R $USER:$USER composeexample manage.py
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```
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If you are running Docker on Mac or Windows, you should already
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have ownership of all files, including those generated by
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`django-admin`. List the files just to verify this.
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```console
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$ ls -l
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total 32
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-rw-r--r-- 1 user staff 145 Feb 13 23:00 Dockerfile
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drwxr-xr-x 6 user staff 204 Feb 13 23:07 composeexample
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-rw-r--r-- 1 user staff 159 Feb 13 23:02 docker-compose.yml
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-rwxr-xr-x 1 user staff 257 Feb 13 23:07 manage.py
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-rw-r--r-- 1 user staff 16 Feb 13 23:01 requirements.txt
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```
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### Connect the database
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In this section, you set up the database connection for Django.
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1. In your project directory, edit the `composeexample/settings.py` file.
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2. Replace the `DATABASES = ...` with the following:
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```python
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# settings.py
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import os
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[...]
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DATABASES = {
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'default': {
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'ENGINE': 'django.db.backends.postgresql',
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'NAME': os.environ.get('POSTGRES_NAME'),
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'USER': os.environ.get('POSTGRES_USER'),
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'PASSWORD': os.environ.get('POSTGRES_PASSWORD'),
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'HOST': 'db',
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'PORT': 5432,
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}
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}
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```
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These settings are determined by the
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[postgres](https://hub.docker.com/_/postgres) Docker image
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specified in `docker-compose.yml`.
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3. Save and close the file.
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4. Run the [docker compose up](https://docs.docker.com/engine/reference/commandline/compose_up/) command from the top level directory for your project.
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```console
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$ docker compose up
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djangosample_db_1 is up-to-date
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Creating djangosample_web_1 ...
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Creating djangosample_web_1 ... done
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Attaching to djangosample_db_1, djangosample_web_1
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db_1 | The files belonging to this database system will be owned by user "postgres".
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db_1 | This user must also own the server process.
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db_1 |
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db_1 | The database cluster will be initialized with locale "en_US.utf8".
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db_1 | The default database encoding has accordingly been set to "UTF8".
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db_1 | The default text search configuration will be set to "english".
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<...>
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web_1 | July 30, 2020 - 18:35:38
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web_1 | Django version 3.0.8, using settings 'composeexample.settings'
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web_1 | Starting development server at http://0.0.0.0:8000/
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web_1 | Quit the server with CONTROL-C.
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```
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At this point, your Django app should be running at port `8000` on
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your Docker host. On Docker Desktop for Mac and Docker Desktop for Windows, go
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to `http://localhost:8000` on a web browser to see the Django
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welcome page.
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> Note:
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>
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> On certain platforms (Windows 10), you might need to edit `ALLOWED_HOSTS`
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> inside `settings.py` and add your Docker host name or IP address to the list.
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> For demo purposes, you can set the value to:
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>
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> ```python
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> ALLOWED_HOSTS = ['*']
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> ```
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>
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> This value is **not** safe for production usage. Refer to the
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> [Django documentation](https://docs.djangoproject.com/en/1.11/ref/settings/#allowed-hosts) for more information.
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5. List running containers.
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In another terminal window, list the running Docker processes with the `docker ps` or `docker container ls` command.
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```console
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$ docker ps
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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def85eff5f51 django_web "python3 manage.py..." 10 minutes ago Up 9 minutes 0.0.0.0:8000->8000/tcp django_web_1
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678ce61c79cc postgres "docker-entrypoint..." 20 minutes ago Up 9 minutes 5432/tcp django_db_1
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```
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6. Shut down services and clean up by using either of these methods:
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* Stop the application by typing `Ctrl-C` in the same shell in where you
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started it:
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```console
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Gracefully stopping... (press Ctrl+C again to force)
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Killing test_web_1 ... done
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Killing test_db_1 ... done
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```
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* Or, for a more elegant shutdown, switch to a different shell, and run
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[docker compose down](https://docs.docker.com/engine/reference/commandline/compose_down/) from the top level of your
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Django sample project directory.
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```console
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$ docker compose down
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Stopping django_web_1 ... done
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Stopping django_db_1 ... done
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Removing django_web_1 ... done
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Removing django_web_run_1 ... done
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Removing django_db_1 ... done
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Removing network django_default
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```
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Once you've shut down the app, you can safely remove the Django project directory (for example, `rm -rf django`).
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## More Compose documentation
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* [Docker Compose overview](https://docs.docker.com/compose/)
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* [Install Docker Compose](https://docs.docker.com/compose/install/)
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* [Getting Started with Docker Compose](https://docs.docker.com/compose/gettingstarted/)
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* [Docker Compose Command line reference](https://docs.docker.com/compose/reference/)
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* [Compose file reference](https://docs.docker.com/compose/compose-file/)
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* [Awesome Compose Django sample application](../../django/README.md)
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