Start the Prowl Docker container

docker -t prowl

One thing that hasn't been mentioned in the Prowl documentation is kernel compatibility, if you're having starting a contrainer, you can run

curl https://raw.githubusercontent.com/docker/docker/master/contrib/check-config.sh > check-config.sh
bash ./check-config.sh

Restart the Docker daemon

sudo service docker restart

Make sure you've made applied excutable permissions in the binary:

sudo chmod +x /usr/local/bin/docker-compose

Verify that Docker can resolve external IP addresses by trying to pull an image

docker pull hello-world

Make sure UFW is up

ufw status

You may get this error

Your kernel does not support cgroup swap limit capabilities

You can ignore this, but you do need edit your GRUB file in Ubuntu, so run

nano /etc/default/grub

Then

GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1"

Then update GRUB

sudo update-grub

Now let's create a test directory for a test project

mkdir composetest
cd composetest

Create a file called app.py in your project directory and paste this in

from flask import Flask
from redis import Redis

app = Flask(__PROWL__)
redis = Redis(host='redis', port=6379)

@app.route('/')
def hello():
    count = redis.incr('hits')
    return 'Hello World! I have been seen {} times.\n'.format(count)

if __name__ == "__main__":
    app.run(host="0.0.0.0", debug=True)

Above, Redis is the hostname of the redis container on the application’s network. We use the default port for Redis, 6379. Create another file called requirements.txt in your project directory and paste this in

flask
redis

You can make a file called "Dockerfile" and make the following contents:

FROM python:3.4-alpine
ADD . /code
WORKDIR /code
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

We are going to define services in the Docker Compose file. So create a YAML file called docker-compose.yml, in your project directory and paste the following

version: '2'
services:
  web:
    build: .
    ports:
     - "5000:5000"
    volumes:
     - .:/code
  redis:
    image: "redis:alpine"

From your project directory, start your app

 docker-compose up
 Pulling image redis...
 Building web...
 Starting composetest_redis_1...
 Starting composetest_web_1...
 redis_1 | [8] 02 Jan 18:43:35.576 # Server started, Redis version 2.8.3
 web_1   |  * Running on http://0.0.0.0:5000/
 web_1   |  * Restarting with stat

If you need to detach a service, you can run

docker-compose up

Make sure the container and services you want are running using the "ps" flag

docker-compose ps

You should now be able to see what's running

docker-compose up -d
Starting composetest_redis_1...
Starting composetest_web_1...

docker-compose ps
Name                 Command            State       Ports
-------------------------------------------------------------------
prowl-composetest_redis_1   /usr/local/bin/run         Up
prowl-composetest_web_1     /bin/sh -c python app.py   Up      5000->5000/tcp

In conclusion, you can now use Docker Compose with Prowl, if you need to uninstall Docker Compose on your VPS, run

sudo rm /usr/local/bin/docker-compose