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Basics

⬅️ Back to Docker overview

Run the first container

docker run hello-world

Let's try the example which Docker Desktop suggests.

docker run --detach --publish 8001:80 docker/getting-started

Visit http://localhost:8001 to view the getting-started page.

  • 💡 The first port is the host port, the second the container port.
  • 💡 You don't need to write the URL Docker Desktop already provides the link via GUI via Container/Apps.

Run a Nginx web server and discover it

Let's start a Nginx container.

docker run --name hello_world --publish 8002:80 --detach nginx

Visit http://localhost:8002 to view the default nginx page.

  • 💡 The option -d is short for --detach, which means you just run the container and then detach from it. Essentially, you the run container in the background. Default is the attach mode.
  • 💡 Instenad of using --detach you can use the short version -d and -p instead of --publish.

List containers

docker ps

💡 If you don't use a name for your container an ID will be created.

List all containers including exited container.

docker ps -a

Want to automatically remove the container when it exits. Use the rm flag.

docker run --rm -p 8003:80 -d nginx

💡 Possible States of a Docker Container: Running, Restarting, Exited, Paused and Dead. Show stats: The docker stats command returns a live data stream for running containers.

docker stats hello_world

Docker top to display the running processes of a container.

docker top hello_world

Show Logs and follow the log output

docker logs -f hello_world

Stop the container

docker stop hello_world

💡 A stopped container is in the state exited.

Exercise

  • 📝Run your first "Hello World" container.
  • 📝Can you find the container in your Docker Desktop GUI and stop it there?

Start the container

docker start hello_world

Rename the container

docker container rename hello_world hello_world_neu

Remove the container

docker rm hello_world_neu

💡Only stopped container can be removed.

If you don't want to stop it before ...

docker rm -f hello_world_neu

To delete all running and stopped containers on the host.

docker rm -f $(docker ps -aq)

Exercise

  • 📝Start three different Nginx containers. Did you have any challenges and how did you solve them?
  • 📝Start a docker container, open Nginx in the browser and follow the logs via command line. Then reload the page.
  • 📝Run a container with Wordpress. The appropriate image can be found here. https://hub.docker.com/_/wordpress

CLI - docker

  • Restructured in 2017. https://www.docker.com/blog/whats-new-in-docker-1-13/
  • Using an object is more structured but not necessary
  • docker <object> <command> <options>
  • Container is the object for docker run. Other objects are fore example image, network or volume.
  • The CLI support tab completion. For instance write docker i and press the tab key. All possible option should be displayed.

These two commands have the same result.

docker run hello-world
docker container run hello-world

Show the status of client and daemon components

docker version

Show the engine version only

docker --version

More information about the docker host, e.g. numbers of containers

docker system info

If you need help

docker 
docker run --help
docker container --help
docker container run --help

Exercise

  • 📝 Use Docker help to figure out how to list all images.
  • 📝 Figure out how to get the last three log entries of a container.

Container which automatically restart

If you reboot your system, your running container will not be alive. Unless you use --restart always.

docker run -d --restart always -p 8005:80 --name my_server nginx
docker container update --restart unless-stopped my_server
docker container inspect my_server

Run a command inside the container

Start a container and execute a command.

docker run ubuntu cat /etc/*release*
docker run -it ubuntu

💡 The option -it is short for --interactive + --tty. When you docker run with this command it takes you straight inside the container.

Run a command in an existing container.

docker exec -it my_server cat /etc/*release*
# terminal into the docker container
docker exec -it my_server bash

Exercise

  • 📝 The Docker Desktop provides the CLI option. Can you find it?