Summary - Volumes

Combine create, mount and remove to set up persistent data.

Summary: volumes

In this group:

The writable layer is temporary; persistent data is kept in a volume or bind mount.
Docker manages named volumes; they're created on first use and stay when the container is removed.
A bind mount mounts a host path; it's used in development for code and configuration files.
-v is the short form, --mount the explicit form; :ro/readonly is read-only.
docker volume ls/inspect/rm/prune manage them; backups are made by taking a tar with a temporary container.

docker run -d -v pgdata:/var/lib/postgresql/data postgres:16
docker run -d -v "$PWD/site":/usr/share/nginx/html:ro nginx

Exercise Data and code

Write two commands: start a container named db from mysql:8 in the background with MYSQL_ROOT_PASSWORD=gizli, mounting the mysqldata volume at /var/lib/mysql; start a container named web from php:8.3-apache in the background mapping 8080 to 80 and mounting the current folder ("$PWD") at /var/www/html.

Show example solution

docker run -d --name db -e MYSQL_ROOT_PASSWORD=gizli -v mysqldata:/var/lib/mysql mysql:8
docker run -d --name web -p 8080:80 -v "$PWD":/var/www/html php:8.3-apache

Test yourself

What is the difference between -v ./veri:/data and -v veri:/data?
- The second is temporary
- The first is a bind mount, the second a named volume
- They are the same
- The first is read-only
Show answer

The first is a bind mount, the second a named volume — If the source is a path it's a bind mount, if it's a plain name it's a volume.

Clean up unused volumes.

docker volume ____ -f

Show answer

docker volume prune -f

Match.

named volume

Production data
bind mount

Development code
:ro

No writing
volume prune

Cleanup

Next lesson: The -e flag

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