Exploring the Ins and Outs of Docker Network and Volume Configuration

Hello everyone,

This is day 20 of #90DaysOfDevops challenge initiated by Shubham Londhe. In this blog, we will be covering the following tasks

• Understand docker volume and Docker network.

• Learn how to use Docker Volumes and Named Volumes to share files and directories between multiple containers.

• Create two or more containers that read and write data to the same volume using the docker run --mount command.

Introduction: Docker revolutionized containerization by providing powerful tools for isolating and deploying applications. Two fundamental concepts in Docker are volumes and networks. In this blog post, we will explore Docker volumes and networks in detail, focusing on how they enable seamless data sharing between multiple containers. Additionally, we'll demonstrate how to create containers that read and write data to the same volume using the docker run --mount command. Finally, we'll verify the consistency of data across containers using the docker exec command.

Docker Volume

Docker allows you to create something called volumes. Volumes are like separate storage areas that can be accessed by containers. They allow you to store data, like a database, outside the container, so it doesn't get deleted when the container is deleted. You can also mount from the same volume and create more containers having the same data.

1. Sharing Files and Directories Between Containers with Docker Volumes:

   Docker volumes allow for persistent data storage and sharing between containers. Named volumes provide a convenient way to manage and access data. Here's how to use Docker Volumes and Named Volumes to share files and directories between multiple containers:

Here's an example of how to create multiple containers that read and write data to the same volume using the docker run --mount command:

Step 1: Create a Named Volume:

Step 2: Run the First Container and Mount the Named Volume:

This command creates the first container named "container1" and mounts the named volume "myvolume" to the target path "/path/in/container1" inside the container.

Step 3: Run the Second Container and Mount the Same Named Volume:

This command creates the second container named "container2" and mounts the same named volume "myvolume" to the target path "/path/in/container2" inside the container.

Now, both "container1" and "container2" can read from and write to the shared volume "myvolume" at their respective mount paths ("/path/in/container1" and "/path/in/container2").

With bind mounts, changes made to the host directory will be reflected in both containers.

These commands will allow you to create a named volume or bind mount and mount/bind it to multiple containers for sharing files and directories.

1. Creating Containers that Share Data with the Same Volume:

   To demonstrate how to create multiple containers that read and write data to the same volume, we can use the docker run --mount command:

   • step 1. Create the Named Volume:

     

   • step 2. Run the First Container and Mount the Named Volume:

     

   • step 3. Run the Second Container and Mount the Same Named Volume:

     

     By sharing the named volume between the containers, they can read from and write to the shared volume, ensuring data consistency across the containers.

By running appropriate commands using docker exec, you can verify that the data within the mounted volumes is consistent across all containers.

Conclusion:

Docker volumes and networks are crucial components for effective containerization. They provide mechanisms for sharing data and enabling communication between containers. By utilizing Docker Volumes and Named Volumes, you can easily share files and directories between multiple containers. Additionally, by creating containers that read and write data to the same volume using the docker run --mount command, you can ensure data consistency across containers. Finally, by using the docker exec command, you can conveniently verify the shared data within each container. Understanding these concepts empowers developers to build scalable and interconnected containerized applications with ease.