app.run(host="0.0.0.0", port=8000, debug=True)
    ```

3.  Create a file called `requirements.txt` and paste these two lines in:

    ```none
    flask
    redis
    ```

4.  Create a file called `Dockerfile` and paste this in:

    ```dockerfile
    # syntax=docker/dockerfile:1
    FROM python:3.4-alpine
    ADD . /code
    WORKDIR /code
    RUN pip install -r requirements.txt
    CMD ["python", "app.py"]
    ```

5.  Create a file called `compose.yaml` and paste this in:

    ```yaml
      services:
        web:
          image: 127.0.0.1:5000/stackdemo
          build: .
          ports:
            - "8000:8000"
        redis:
          image: redis:alpine
    ```

    The image for the web app is built using the Dockerfile defined
    above. It's also tagged with `127.0.0.1:5000` - the address of the registry
    created earlier. This is important when distributing the app to the
    swarm.


## Test the app with Compose

1.  Start the app with `docker compose up`. This builds the web app image,
    pulls the Redis image if you don't already have it, and creates two
    containers.

    You see a warning about the Engine being in swarm mode. This is because
    Compose doesn't take advantage of swarm mode, and deploys everything to a
    single node. You can safely ignore this.

    ```console
    $ docker compose up -d

    WARNING: The Docker Engine you're using is running in swarm mode.

    Compose does not use swarm mode to deploy services to multiple nodes in
    a swarm. All containers are scheduled on the current node.

    To deploy your application across the swarm, use `docker stack deploy`.

    Creating network "stackdemo_default" with the default driver
    Building web
    ...(build output)...
    Creating stackdemo_redis_1
    Creating stackdemo_web_1
    ```

2.  Check that the app is running with `docker compose ps`:

    ```console
    $ docker compose ps

          Name                     Command               State           Ports
    -----------------------------------------------------------------------------------
    stackdemo_redis_1   docker-entrypoint.sh redis ...   Up      6379/tcp
    stackdemo_web_1     python app.py                    Up      0.0.0.0:8000->8000/tcp
    ```

    You can test the app with `curl`:

    ```console
    $ curl http://localhost:8000
    Hello World! I have been seen 1 times.

    $ curl http://localhost:8000
    Hello World! I have been seen 2 times.

    $ curl http://localhost:8000
    Hello World! I have been seen 3 times.
    ```

3.  Bring the app down:

    ```console
    $ docker compose down --volumes

    Stopping stackdemo_web_1 ... done
    Stopping stackdemo_redis_1 ... done
    Removing stackdemo_web_1 ... done
    Removing stackdemo_redis_1 ... done
    Removing network stackdemo_default