Volumes in Compose in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a volume in Docker Compose?

A volume is a storage area outside the container's writable layer. It keeps data safe even if the container is deleted or recreated.

beginner

How do you define a named volume in a docker-compose.yml file?

You define it under the 'volumes:' key at the bottom of the file, like this:<br>

volumes:
  mydata:

intermediate

What is the difference between a bind mount and a volume in Docker Compose?

A bind mount links a host folder directly to the container, while a volume is managed by Docker and stored in Docker's storage area.

beginner

How do you attach a volume to a service in docker-compose.yml?

Under the service, use the 'volumes:' key and specify the volume name and container path, like:<br>

volumes:
  - mydata:/app/data

beginner

Why use volumes in Docker Compose?

Volumes keep data persistent, share data between containers, and separate data from container lifecycle.

Where are Docker volumes stored by default?

A Inside the container's writable layer

B In the container's memory

C On a remote cloud server

D In Docker's managed storage area on the host

Docker volumes are stored in a special area on the host managed by Docker, separate from the container's writable layer.

How do you declare a volume for a service in docker-compose.yml?

A In the Dockerfile

B Under the service's 'volumes:' key with volume_name:container_path

C Under the 'services:' key only

D By running a docker volume create command inside the container

Volumes are declared under the service's 'volumes:' key in docker-compose.yml using the format volume_name:container_path.

What happens to data in a volume if the container is deleted?

A Data is moved to a backup folder automatically

B Data is deleted with the container

C Data remains safe in the volume

D Data is lost permanently

Volumes keep data safe even if the container is deleted or recreated.

Which of these is NOT a benefit of using volumes?

A Increasing container CPU speed

B Sharing data between containers

C Separating data from container lifecycle

D Data persistence

Volumes help with data persistence and sharing but do not affect container CPU speed.

What is a bind mount in Docker Compose?

A A direct link between a host folder and container folder

B A volume managed by Docker

C A network connection between containers

D A special type of container

A bind mount links a host folder directly to a container folder.

Explain how to define and use a volume in a docker-compose.yml file.

Think about where volumes are declared and how services use them.

Describe the benefits of using volumes in Docker Compose.

Why do we want data to live outside containers?