Day 19:Docker for DevOps Engineers

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 same data.

Docker Network:

Docker allows you to create virtual spaces called networks, where you can connect multiple containers (small packages that hold all the necessary files for a specific application to run) together. This way, the containers can communicate with each other and with the host machine (the computer on which the Docker is installed). When we run a container, it has its own storage space that is only accessible by that specific container. If we want to share that storage space with other containers, we can't do that.

Task-1

Create a multi-container docker-compose file which will bring UP and bring DOWN containers in a single shot ( Example - Create application and database container )

We have a docker-compose yml file from our previous articles

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 down command to stop and remove all containers, networks, and volumes associated with the application

command is : sudo docker-compose down

Task-2

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

docker volume create --name volume-data

run our container:

docker run -d -v volume-data:/data --name nginx-test nginx:latest

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

docker volume create --name first-volume-data && docker volume create --name second-volume-data

Suppose we want to mount two different volumes for our web application, but one of those paths must be read-only.

If we are using the command line, we can use the -v option:

docker run -d -p 8080:8080 -v first-volume-data:/container-path-1 -v second-volume-data:/container-path-2:ro --name web-app web-app:latest

Use the docker volume ls command to list all volumes

command : docker volume ls

Use the docker volume rm command to remove the volume when you're done

command : docker volumne rm "volume name"