Welcome to the comprehensive guide on deploying a two-tier Flask application using Docker! This tutorial will walk you through every step to ensure a smooth setup.

Let's get started!

Installation and Setup

1. Launch EC2 instance

2. Install Docker

  sudo apt update
  sudo apt install docker.io

3. Verify Docker installation by checking active processes:

docker ps

4. Clone the Two-Tier Flask App Repository

https://github.com/sanchit1498/two-tier-flask-app.git

Create and Edit Docker file

1. Create a Dockerfile to build the image for your Flask app:

  FROM python:3.9-slim

  WORKDIR /app

  RUN apt-get update -y \
          && apt-get upgrade -y \
          && apt-get install -y gcc default-libmysqlclient-dev pkg-config \
          && rm -rf /var/lib/apt/lists/*

  COPY requirements.txt .

  RUN pip install mysqlclient
  RUN pip install -r requirements.txt

  COPY . .

  CMD ["python","app.py"]

2. Build the Docker image for your Flask app:

  docker build . -t myflaskapp

3. List Docker images to ensure your image is created:

  docker images

4. Create a Docker network for communication between containers:

  docker network create twotier
  docker network ls
  docker network inspect twotier

5. Run MySQL Container with specified environment variables:

  docker run -d -p 3306:3306 --network=twotier -e MYSQL_DATABASE=myDb -e MYSQL_USER=admin -e MYSQL_PASSWORD=admin -e MYSQL_ROOT_PASSWORD=admin --name=mysql mysql:5.7

6. Launch the Flask app container with connections to the MySQL container:

  docker run -d -p 5000:5000 --network=twotier -e MYSQL_HOST=mysql -e MYSQL_USER=admin -e MYSQL_PASSWORD=admin -e MYSQL_DB=myDb --name=myflaskapp flaskapp:latest

7. Ensure both containers are running and connected:

docker ps
docker network inspect twotier

Push Flask App Image to Docker Hub

1. Log in to Docker Hub:

docker login
# Enter your ID & Password

2. Tag and push your image:

docker tag flaskapp:latest myflaskapp:latest
docker images
docker push your_user_name/repositry_name:latest

Access Container Shell

docker exec -it <container_id> bash

Set up the database and table

mysql -u root -p
# Enter your Password
use myDb;     # Select database
CREATE TABLE messages (
    id INT AUTO_INCREMENT PRIMARY KEY,
    message TEXT
);
#create tables in database

Verify the app is running by hitting the following URL in the browser:

URL: server_ip:5000

Docker Compose Configuration

To avoid running two separate commands for each container, you can use Docker Compose to run both simultaneously. To do this, use a text editor to create or modify the Docker Compose configuration file.

1. Install Docker Compose

apt install docker-compose

2. Create the Docker Compose configuration file:

version: '3'
services:
  backend:
    image: sanchit1498/myflaskapp:latest
    ports:
      - "5000:5000"
    environment:
       MYSQL_HOST: "mysql"
       MYSQL_USER: "admin"
       MYSQL_PASSWORD: "admin"
       MYSQL_DB: "myDb"
    depends_on:
      - mysql
  mysql:
    image: mysql:5.7
    environment:
       MYSQL_DATABASE: "myDb"
       MYSQL_USER: "admin"
       MYSQL_PASSWORD: "admin"
       MYSQL_ROOT_PASSWORD: "admin"
    ports:
      - "3306:3306"
    volumes:
      - ./message.sql:/docker-entrypoint-initdb.d/message.sql
      - mysql-data:/var/lib/mysql
volumes:
  mysql-data:

3. Launch Docker Compose:

docker-compose up -d

Conclusion

Congratulations! You've successfully set up a two-tier Flask app on Docker. Feel free to explore, modify, and share your experiences with others in the community. Happy coding!