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docker run basics

Learn the basic use of the docker run command.

docker run basics

It has the form docker run [options] image [command]. A command written after the image replaces the image's default start command:

docker run ubuntu echo "Merhaba"     # echo runs, the container stops
docker run ubuntu cat /etc/os-release # prints the Ubuntu version info

A container stops the moment its main process (here echo) ends. That is why long-running processes like a web server keep the container open, while one-off commands close immediately.

The image tag

An image name has the form name:tag. If no tag is given, latest is used; but latest doesn't mean "newest", it's just the default tag. For reproducibility the version should always be written:

docker run ubuntu:24.04 cat /etc/os-release
docker run python:3.12-slim python --version   # Python 3.12.x

Practice Passing a command

Write the command that runs python --version in the python:3.12-slim image and deletes the container when done.

Starter code

terminal
# buraya yaz

Expected output

Python 3.12.7

Questions and answers

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

1 What is the container's state after docker run ubuntu echo merhaba?

  • Paused
  • Stopped (Exited), because the main process ended Correct answer
  • Running
  • Removed

Explanation: A container's lifetime is tied to its main process.

2 Use a specific Ubuntu version.

Question 
docker run ubuntu____ cat /etc/os-release
Answer 
docker run ubuntu:24.04 cat /etc/os-release

Explanation: The tag is written with a colon.

3 Match.

Term Meaning
ubuntu ubuntu:latest
echo merhaba Replaces the default command
Exited Main process ended
python:3.12-slim Versioned tag

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