Day 19 Task: Exploring Docker Volume and Network Concepts

This is #90DaysofDevops challenge under the guidance of Shubham Londhe sir.

• Welcome back to our DevOps journey! Today, we'll dive deeper into Docker Volume and Docker Network concepts, enhancing your proficiency with Docker-compose.yml. Let's explore each task with practical examples and easy-to-understand commands.

Understanding Docker Volume

• Docker volumes provide separate storage areas accessible by containers, enabling us to store critical data outside the container's scope. Let's explore our docker-compose.yml file with an illustrative example:

version: '3'

services:
  web:
    image: supriya279/quiz-app-new1:latest
    ports:
      - "5000:5000"  # Map container port 5000 to host port 5001 for the first container
      - "6007:7000"  # Map container port 6001 to host port 5002 for the second container
      - "6005:6000"  # Map container port 6002 to host port 5003 for the third container
    restart: always
    environment:
      - FLASK_APP=app.py
      - FLASK_ENV=development
    volumes:
      - webvolume:/data
  db:
    image: mysql:latest
    ports:
      - "3306:3306"
    environment:
      - "MYSQL_ROOT_PASSWORD=test@123"

volumes:
  webvolume:

In this docker-compose.yml file:

• We define two services: web for our web application and db for the database.

• The web service exposes port 5000, allowing access to the application.

• The db service exposes port 3306 for database connectivity.

• Both services are configured with specific environment variables for smooth operation.

Exploring Docker Network

• Docker empowers you to create virtual networks, enabling seamless communication between containers and with the host machine. Containers running within the same network can effortlessly exchange information and resources, fostering a cohesive and interconnected environment. Unlike containers' isolated storage spaces, Docker networks provide a shared space for containers to interact and collaborate.

Task-1: Creating a Multi-Container Docker-Compose File

Let's follow these steps:

• Launch the multi-container application in detached mode:

    docker-compose up -d
  

  

• Scale the services as needed:

    docker-compose scale web=3
  

  

• This command scales the web service to have three replicas. You can adjust the number as per your requirements for load balancing or redundancy.

• Monitor container statuses:

    docker-compose ps
  

  

• View logs for a specific service:

    docker-compose logs <service_name>
  

  

• Stop and remove all containers:

    docker-compose down
  

  

Task-2: Harnessing Docker Volumes and Named Volumes

Here's how to accomplish this task:

1. Create containers interacting with a shared volume:

    docker run --mount source=myvolume,target=/data myimage
   

   

2. Verify data consistency across containers:

    docker exec <container_id> ls /data
   

   

3. List all volumes:

    docker volume ls
   

   

4. Remove the volume:

    docker volume rm <volume_name>
   

   

• Mastering these Docker concepts equips you with powerful tools to manage containerized environments effectively. Stay tuned for more insights and practical tips in our future sessions!

Thanks for reading! 💚 Happy reading!