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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

Practice 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.

Starter code

terminal
# buraya yaz

Sample solution

terminal
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

Expected output

708192a3b4c5
8192a3b4c5d6

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 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 Correct answer
  • They are the same
  • The first is read-only

Explanation: If the source is a path it's a bind mount, if it's a plain name it's a volume.

2 Clean up unused volumes.

Question 
docker volume ____ -f
Answer 
docker volume prune -f

Explanation: prune deletes unused ones; -f doesn't ask.

3 Match.

Term Meaning
named volume Production data
bind mount Development code
:ro No writing
volume prune Cleanup

All lessons in Beginner

1 What is Docker?

  1. What is Docker?
  2. Containers and virtual machines
  3. Images and containers
  4. Docker architecture
  5. Use cases
  6. Summary - What is Docker

2 Installation and first commands

  1. Installing Docker
  2. docker version
  3. docker info
  4. The hello-world container
  5. Docker Desktop
  6. Summary - Installation

3 First container

  1. docker run basics
  2. Running in the background
  3. docker ps
  4. docker stop and rm
  5. docker logs
  6. Summary - First container

4 Dockerfile basics

  1. What is a Dockerfile?
  2. The FROM instruction
  3. The RUN instruction
  4. COPY and ADD
  5. CMD and ENTRYPOINT
  6. Summary - Dockerfile

5 Build and images

  1. docker build
  2. Tagging images
  3. Build context
  4. Layers and cache
  5. .dockerignore
  6. Summary - Build

6 docker run options

  1. Interactive mode
  2. Naming containers
  3. Restart policy
  4. Working directory
  5. Switching users
  6. Summary - docker run

7 Image management

  1. docker images
  2. docker rmi
  3. docker pull
  4. docker push
  5. docker tag
  6. Summary - Image management

8 Port mapping

  1. The port concept
  2. The -p flag
  3. Multiple ports
  4. Random ports
  5. IP binding
  6. Summary - Port mapping

9 Volumes and data

  1. Data persistence
  2. Named volumes
  3. The -v flag
  4. Bind mounts
  5. Volume management
  6. Summary - Volumes

10 Environment variables

  1. The -e flag
  2. The ENV instruction
  3. The ARG instruction
  4. env-file
  5. The WORKDIR instruction
  6. Summary - Environment

11 Project: docker-compose

  1. Compose design
  2. Service definition
  3. Database service
  4. Volume and network
  5. Putting it together - compose

12 Docker Hub and registry

  1. What is Docker Hub?
  2. docker login
  3. Searching images
  4. Official images
  5. Private registry
  6. Summary - Registry

13 Network basics

  1. Network drivers
  2. docker network ls
  3. Bridge network
  4. Container connectivity
  5. Publishing ports
  6. Summary - Network

14 Beginner final

  1. Challenge - Dockerfile
  2. Challenge - Build and run
  3. Challenge - Volume
  4. Challenge - Compose
  5. Challenge - Beginner project