Simple Voting Application 🗳️

"Five Docker Containers! Perfectly Balanced, As All Things Should Be!" - DevOps Thanos

A great sample application for docker & docker compose demonstration!

Indeed, this is a distributed application running across multiple Docker containers.

🏗️ 0. Installation and Setup

Make sure the port numbers below as allowed in your host machine for this application:
- 8080
- 8081
Install Git:

yum install -y git

Install Docker:

yum install -y docker

Start Docker:

service docker start

Git clone this repository:

git clone https://github.com/TomHuynhSG/simple-voting-application.git

Change current directory inside it:

cd simple-voting-application

🐳 1. Docker Step by Step

Change current directory to vote directory which contains the voting website:

cd vote

Checkout the Dockerfile of that voting website:

cat Dockerfile

Build a Docker image of voting application:

docker build . -t voting-app

Check if the new voting-app is there:

docker images

Run a Docker container from the Redis image of DockerHub:

docker run -d --name=redis redis

Run a Docker container from the voting app image ➜ The voting website is now live via port 8080:

docker run -d -p 8080:80 --link redis:redis voting-app

Run a Docker container from the Postgres image of DockerHub:

docker run -d --name=db -e POSTGRES_PASSWORD=postgres postgres:9.4

Change current directory to worker-app directory:

cd ../worker

Build a Docker image of worker app:

docker build . -t worker-app

Run a Docker container from the worker app image:

docker run -d --link redis:redis --link db:db worker-app

Change current directory to result directory which contains the result website:

cd ../result

Build a Docker image of result app:

docker build . -t result-app

Run a Docker container from the result app image ➜ The result website is now live via port 8081:

docker run -d -p 8081:80 --link db:db result-app

🐳 2. Docker Compose

Instead of running these above Docker commands one by one. We can use docker compose which allow us to define and run multi-container Docker applications at once.

First, let's stop and remove all containers so we can start from scratch:

docker kill $(docker ps -q)
docker rm $(docker ps -a -q)

Install Docker compose:

sudo curl -L https://github.com/docker/compose/releases/latest/download/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

Check the version of docker compose:

docker-compose version

Create a "docker-compose.yml" file as following:

version: "3"
services:
 redis:
   image: redis
 
 db:
  image: postgres:9.4
  environment:
   POSTGRES_PASSWORD: "postgres"
 
 vote:
   image: voting-app
   ports:
     - 8080:80
   links:
     - redis
 
 worker:
   image: worker-app
   links:
     - db
     - redis
 
 result:
   image: result-app
   ports:
     - 8081:80
   links:
     - db

Run the docker compose file:

docker-compose up

Check if the website is up and running via port 8080 (voting website) and 8081 (result website).

🌟 Screenshots

Voting page:
Result page:

⚙️ Architecture

A front-end web app (Flask) in Python which lets you vote between two options.
A Redis queue which collects new votes.
A .NET Core 3.1, Java worker which consumes votes and stores them in Postgres databased container.
A Postgres database.
A Node.js webapp which shows the results of the voting in real time.

💡 Reference

Modified and simplified based on the official Docker sample voting app (https://github.com/dockersamples/example-voting-app)

🏆 Author

Huynh Nguyen Minh Thong (Tom Huynh) - tomhuynhsg@gmail.com

TomHuynhSG/Simple-Voting-Application-Docker