Docker example

app.py

from flask import Flask
from redis import Redis, RedisError
import os
import socket

redis = Redis(host='redis', db=0, socket_connect_timeout=2, socket_timeout=2)
app = Flask(__name__)

@app.route('/')
def hello():
  try:
    visits = redis.incr("cnt")
  except RedisError:
    visits = "<i>Redis Error</i>"

  html = "<h3>Hello {name}!</h3>  <b>Hostname: {hostname}</b><br/>  Visits: <i>{visits}</i>"
  return html.format(name=os.getenv("NAME", "world"), hostname=socket.gethostname(), visits=visits)

if __name__=='__main__':
  app.run(host='0.0.0.0', port=80)

docker-compose.yml

version: "3"
services:
  web:
    build: .
#    image: friendlyhello   #Create image as   docker build -t friendlyhello .
    ports:
      - "4000:80"
    links:
      - redis
  redis:
    image: redis
    volumes:
      - "/Users/mabit/Documents/Nitin/NitinSandbox/dockery/pything01/data:/data"
    command: redis-server --appendonly yes

docker-compose.yml.bak

version: "3"
services:
  web:
    image: friendlyhello
    deploy:
      replicas: 1
      restart_policy:
        condition: on-failure
      resources:
        limits:
          cpus: "0.5"
          memory: 50M
    ports:
      - "4000:80"
    networks:
      - webnet
  redis:
    image: redis
    ports:
      - "6379:6379"
    volumes:
      - "/Users/mabit/Documents/Nitin/NitinSandbox/dockery/pything01/data:/data"
    deploy:
      placement:
        constraints: [node.role==manager]
    command: redis-server --appendonly yes
    networks:
      - webnet
networks:
  webnet:

Dockerfile

FROM python:2.7-slim
WORKDIR /app
ADD . /app
RUN pip install --trusted-host pypi.python.org -r requirements.txt
EXPOSE 80
ENV NAME World
CMD [ "python", "app.py" ]

requirements.txt

Flask
Redis