dockercompose-sampleapp

A demo on how to use docker-compose to create a Web Service connected to a Redis Database.

We would use an exampled on the lines of the one used by Docker to illustrate basic Compose functionality. This is a simple Python App that sets up a simple webpage displaying the number of hits to that page and and uses Redis backend to store the number of hits to that page.

This inormation would be stored in the variable 'totalhits' in redis.

Getting Started - Installation

We have to start by installing Docker and Docker Compose on your machine.

Install Docker : Docker and Install Docker Compose : Docker Compose

After installing Docker and Docker Compose we would now get stated by cloning this project onto our docker host machine.

Cloning Git Repository

In order to get started be sure to clone this project onto your Docker Host. Create a directory on your host. Please note that the demo webservices will inherit the name from the directory you create. If you create a folder named test. Then the services will all be named test-web, test-redis, test-lb. Also, when you scale your services it will then tack on a number to the end of the service you scale.

git clone https://github.com/Jay-Wani/dockercompose-sampleapp.git

Analyze the Docker Compose file

We will be using the below docker-compose.yml file to build the ecosystem.

version: '2'
services:
  python-app:
    build: .
    ports:
     - "5000:5000"
    volumes:
     - .:/code
    depends_on:
     - redis
  redis:
    image: redis

The yaml files are highly dependent on the spaces for formatting and running the commands, please ensure that the spaces in your file are exactly as shown in the example above.

Version : This tells us about the version of docker-compose that we are using.

Services : This denotes the configuration of the service that we are building. Step 1 : We build the python-app from the Dockerfile placed in the current working directory where we are working. Step 2 : We map the port no 5000 on the localhost to the port 5000 on the container. Step 3 : We map our current working directory to the /code folder on the container Step 4 : We configure the container to talk to the redis container

redis : We setup the redis container from the redis image

Analyze the Dockerfile

We will use this Dockerfile to build the image of webservices app container.

ADD . /sampleapp
WORKDIR /sampleapp
RUN apk-install python \
    python-dev \
    py-pip &&\
    pip install -r requirements.txt
CMD ["python", "app.py"]

Compose Commands for bringing up the app.

docker-compose up -d

Command for building your own image from Dockerfile

docker build -t sampleapp .