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docker info

Learn to get system status with docker info.

docker info

docker info shows the daemon's detailed state: how many containers are running or stopped, how many images there are, the storage driver (usually overlay2), the Docker root directory, and the amount of CPU and memory.

$ docker info
Containers: 3
 Running: 1
 Paused: 0
 Stopped: 2
Images: 5
Storage Driver: overlay2
Docker Root Dir: /var/lib/docker

Disk usage

Docker takes up a lot of space over time. docker system df shows the space used by images, containers, volumes and the build cache; docker system prune cleans up the unused ones:

$ docker system df
TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
Images          5         2         1.2GB     800MB (66%)
Containers      3         1         20MB      15MB (75%)
$ docker system prune     # removes stopped containers, unused networks and dangling images

Practice State and cleanup

Write three commands: show the daemon information, show the disk usage, then clean up the unused items without asking for confirmation (-f).

Starter code

terminal
# buraya yaz

Sample solution

terminal
docker info
docker system df
docker system prune -f

Expected output

Containers: 3
 Running: 1
Total reclaimed space: 815MB

Questions and answers

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

1 Where are image and container layers stored by default on Linux?

  • /etc/docker
  • /home/docker
  • /tmp
  • /var/lib/docker Correct answer

Explanation: "Docker Root Dir" in the docker info output shows this path.

2 Show Docker's disk usage.

Question 
docker system ____
Answer 
docker system df

Explanation: docker system df gives a summary by type.

3 Match.

Term Meaning
docker info Daemon state
docker system df Disk usage
docker system prune Removes unused items
overlay2 Storage driver

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