Part2: 2-tier-app-deployment

In today's blog, let us try to deploy the same flask app through docker-compose instead of Dockerfile.

Why are we doing this?

Well, as we had already seen in my last blog, there were n number of steps involved in deploying a 2-tier app through a docker file like creating containers for each of them separately, creating a network and then attaching a network and so on

What if I say, the same deployment can be done much more easily in less number of steps through Docker-compose?

Dive into the blog to understand more.

Let's start

First, create an EC2 Ubuntu instance on which we shall start working:

First, make sure docker and docker-compose are installed, if not they can be installed through the below shell script. You can check this blog for more information

 sudo apt update
 sudo apt-get install docker.io -y
 sudo systemctl start docker
 sudo systemctl enable docker
 sudo apt-get install docker-compose -y

 echo "Docker and docker-compose installed"

Once the docker setup is complete, we shall start writing the Docker compose file:
1. In the docker file, we will first add the version of docker-compose and the services for which we are creating the containers:
2. Next, we shall add command that will perform the following tasks :
  1. pull the image from dockerhub
  2. build a container out of it
  3. includes port no's to be bound
  4. environment variables required for both flask app and mysql db

        version: '3'  # version of docker compose that is being used
        services: # services that need to be created
          backend:
            image: sowmyabm/flask-app:latest #image that should be pulled from dockerhub
            ports:
              - "5000:5000"
            environment:
              MYSQL_HOST: mysql
              MYSQL_USER: admin
              MYSQL_PASSWORD: admin
              MYSQL_DB: myDb
          mysql:
            image: mysql:5.7
            ports:
              - "3306:3006"
            environment:
              MYSQL_ROOT_PASSWORD: admin
              MYSQL_DATABASE: myDb
              MYSQL_USER: admin
              MYSQL_PASSWORD: admin

Now, as we had already seen in the previous blog, mysql db needs table to be created.
So we shall write a sql script(message.sql) to create a table and add this script to docker's entrypoint so that this srcipt runs simultaneously when the docker conatiner is created.
```
 CREATE TABLE messages (
     id INT AUTO_INCREMENT PRIMARY KEY,
     message TEXT
 );
```
Now we shall write a command that binds the mysql script in the current folder to docker's entry point (./message.mysql:/docker-entrypoint-initdb/message.sql))

Next, we shall create a volume and attach it to mysql(mysql-data:/var/lib/mysql)

   volumes:
     - ./message.sql:/docker-entrypint-initdb.d/message.sql
     - mysql-data:/var/lib/mysql
 volumes:
   mysql-data:

So the contents of docker-compose file will be as follows:


 version: '3'  # version of docker compose that is being used
 services: # services that need to be created
   backend:
     image: sowmyabm/flask-app:latest #image that should be pulled from dockerhub
     ports:
       - "5000:5000" #ports to be bound
     environment:    # environment variables required
       MYSQL_HOST: mysql
       MYSQL_USER: admin
       MYSQL_PASSWORD: admin
       MYSQL_DB: myDb
   mysql:
     image: mysql:5.7 #image to be pulled from dockerhub
     ports:
       - "3306:3006" # ports to be bound
     environment:    # environment variables required
       MYSQL_ROOT_PASSWORD: admin
       MYSQL_DATABASE: myDb
       MYSQL_USER: admin
       MYSQL_PASSWORD: admin

     volumes: 
       - ./message.sql:/docker-entrypint-initdb.d/message.sql #attaching mysql script tp dockers entrypoint
       - mysql-data:/var/lib/mysql #mounting the container;s volume with that of laptop

 volumes:
   mysql-data:

Set the inbound rules to open port no 5000 for the incoming traffic
We have setup everything that is necessary for the application, now we shall deploy the whole application through a single command docker-compose up -d
The application is successfully containerised
We can check if teh app is successfully deplpoyed by accessing it via the web browser on our server's IP

Hence successfully deployed application through docker-compose.

Visit my next blog to understand how to make this application fault tolerant

Part2: 2-tier-app-deployment

Table of contents

Let's start

First, create an EC2 Ubuntu instance on which we shall start working: