🛳️Day 23 in DevOps: Understanding Docker Volume and Network

✨ Docker Volume :

Docker volumes are like special storage areas managed by Docker for your containers. They're better than using regular folders from your computer because:

1. 🛡️ Easy to Backup and Move: Volumes make it easy to save or move data.

2. 🔧 Simple to Manage: Docker gives you easy commands to control volumes.

3. 🌍 Works on Any System: Volumes work on both Linux and Windows.

4. 🔒 Safe Sharing: You can safely share data between multiple containers.

5. ✨ Extra Features: You can do cool things like store data on other computers or encrypt it.

6. 📂 Start with Data: You can start a volume with some data already in it.

7. 🚀 Better Performance: Volumes work faster than regular folders, especially on Mac and Windows.

Think of volumes as a special storage area managed by Docker, making it easy and safe to handle your container data.

✨ Docker Network :

Docker helps you run applications in isolated environments called containers. To manage communication between these containers and the outside world, Docker uses different types of networks:

1. 🌉 Bridge Network:

   • Connects containers to each other and your host.

   • Containers get their own IP address.

   • They can communicate with each other but are isolated from other networks.

2. 🏠 Host Network:

   • Containers use the host’s network directly.

   • No separate IP addresses for containers.

   • Ports used by containers are the same as the host’s ports.

3. 🌐 Overlay Network:

   • Connects containers across multiple Docker hosts.

   • Useful for clusters of Docker hosts (like Docker Swarm).

4. 📡 IPvLAN Network:

   • Gives precise control over IP addresses.

   • Useful for connecting containers to existing networks.

5. 🔌 Macvlan Network:

   • Makes containers appear as physical devices on your network.

   • Each container gets its own MAC address.

✅Task-1: Create a Multi-Container Docker-Compose File

📝 Steps:

1. Create a docker-compose.yml file with the following content:

    version: '3.8'
   
    services:
      web:
        image: nginx:latest
        ports:
          - "80:80"
   
      db:
        image: mysql:latest
        environment:
          MYSQL_ROOT_PASSWORD: example
          MYSQL_DATABASE: sample_db
        volumes:
          - db_data:/var/lib/mysql
   
    volumes:
      db_data:
   

2. Run the following commands:

   • 🚀 Start containers: docker-compose up -d

   • 🔍 Scale web service to 3 instances: docker-compose scale web=3

   • 📋 Check container status: docker-compose ps

   • 📄 View logs for web service: docker-compose logs web

   • 🛑 Stop and remove containers: docker-compose down

✅Task-2: Use Docker Volumes to Share Data Between Containers

📝 Steps:

1. 📦 Create a named volume:

    docker volume create my_shared_volume
   

2. 🐳 Run two containers with the shared volume:

    docker run -d --name container1 --mount source=my_shared_volume,target=/shared_volume alpine tail -f /dev/null
    docker run -d --name container2 --mount source=my_shared_volume,target=/shared_volume alpine tail -f /dev/null
   

3. ✍️ Write data from one container and check it from another:

    docker exec container1 sh -c "echo 'Hello from container1' > /shared_volume/data.txt"
    docker exec container2 cat /shared_volume/data.txt
   

   You should see "Hello from container1" when you check from the second container.

4. 📜 List all volumes and remove the shared volume:

    docker volume ls
    docker volume rm my_shared_volume
   

In summary, Docker volumes are great for sharing data between containers, making it easy to manage and keep your data safe.

Happy Learning! 😊