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The hello-world container

Learn to test the install by running the first container.

What does hello-world prove?

The output of the hello-world container tells you four steps completed successfully in the background:

  1. The CLI connected to the daemon.
  2. The daemon pulled the image from Docker Hub.
  3. The daemon created a new container from the image and ran the program.
  4. The daemon streamed the output to the CLI, which sent it to the terminal.
docker run hello-world

Stopped containers pile up

hello-world stops when it finishes but isn't removed. docker ps -a also shows stopped containers; every run adds a new one. You need to use --rm or clean up with docker container prune:

$ docker ps -a
CONTAINER ID   IMAGE         STATUS                     NAMES
a1b2c3d4e5f6   hello-world   Exited (0) 5 seconds ago   jolly_tesla
$ docker container prune -f

Practice Try and clean up

Write three commands: run hello-world; list all containers (including stopped ones); clean up the stopped containers without asking for confirmation.

Starter code

terminal
# buraya yaz

Sample solution

terminal
docker run hello-world
docker ps -a
docker container prune -f

Expected output

Hello from Docker!
CONTAINER ID   IMAGE         STATUS                     NAMES
a1b2c3d4e5f6   hello-world   Exited (0) 2 seconds ago   jolly_tesla
Deleted Containers:
a1b2c3d4e5f6

Questions and answers

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

1 What is different when hello-world is run a second time?

  • The same container is reused
  • The output becomes Turkish
  • The download step is skipped because the image is local Correct answer
  • It gives an error

Explanation: Each docker run creates a new container; the image comes from the cache.

2 List stopped containers too.

Question 
docker ps ____
Answer 
docker ps -a

Explanation: -a (all) shows all containers.

3 Match.

Term Meaning
Exited (0) Finished successfully
docker ps -a All containers
container prune Removes stopped ones
jolly_tesla Automatically given name

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