DevOps(Day-19) : Docker for DevOps

SPEED1X

TABLE OF CONTENTS

• Docker-Volume

• Docker-Network

• Task - 1

• Task-2

Docker-Volume

Docker allows mounting the filesystems as a volume to the containers. These volumes preserve all the data of the container and the data is persisted even if the container is deleted.

The default path is /var/lib/docker/volumes/ on Linux.

A volume can be mounted to multiple containers and it lies even if all containers are down. It can be removed only manually by the user.

1. Creating a Docker Volume

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     $docker volume create [volume_name]
   

2. Listing a Docker Volume

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     $docker volume list
   

3. Mounting a volume.

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     docker run --mount source=[volume_name],destination=[path_in_container] [docker_image]
   

4. Removing a Volume.

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     $docker volume rm [volume_name]
   

5. Deleting all volumes at once.

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     $docker volume prune
   

Docker-Network

With Docker-Compose we create multiple containers, in that process, a space is created by Docker where those containers can communicate with each other and the host system. That space is known as Docker Network.

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$docker network COMMAND

The COMMAND can be connected, create, disconnect, inspect, ls, prune, and rm.

Task - 1

Create a multi-container docker-compose file which will bring UP and bring DOWN containers in a single shot.

• Use the docker-compose up command with the -d flag to start a multi-container application in detached mode.

  

• Use the docker-compose scale command to increase or decrease the number of replicas for a specific service. You can also add replicas in deployment file for auto-scaling.

  

  

• Use the docker-compose ps command to view the status of all containers, and docker-compose logs to view the logs of a specific service.

  

• Use the docker-compose down command to stop and remove all containers, networks, and volumes associated with the application

  

Task-2

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

  

  Use the below command to create a volume.

  $ docker volume create --name django-volume-final --opt device=/home/ubuntu/devops/volume/django-volume --opt o=bind --opt type=none django-volume-final

  

  

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

  $ docker run -d --name django-notes-app -p 3000:3000 --mount source=django-volume-final,target=/app django-app:v1

  

  

• Verify that the data is the same in all containers by using the docker exec command to run commands inside each container.

  $ docker exec -it django-notes-app-V2 /bin/sh

  

• Use the docker volume ls command to list all volumes and docker volume rm command to remove the volume when you're done.

  

  

Thanks for reading my article. Have a nice day.

WRITTEN BY Biswaraj Sahoo --AWS Community Builder | DevOps Engineer | Docker | Linux | Jenkins | AWS | Git | Terraform | Docker | kubernetes

Empowering communities via open source and education. Connect with me over linktree: linktr.ee/biswaraj333