Docker quick start notes
- Update *: Blog updated to use latest way to install docker.
After reading about docker and containers, I thought let's try them out. Here are my notes. Obviously all of them are taken from Internet. Maybe this collection here will help someone start with docker faster than spending time searching all over the internet.
It assumes your base OS is Ubuntu 14.04 Trusty Tahr (when was the last time you saw the codename spelled ‘Trusty Tahr’ and not ‘Trusty’? :) ).
Ensure kernel version is more than 3.10
uname -r
Install docker
curl -sSL https://get.docker.com/ | sh
See docker version
sudo docker version
Pull an Ubuntu Trusty docker image
sudo docker pull ubuntu:14.04
Alternatively, you can search for a docker image ‘tutorial’ in docker's repository
sudo docker search tutorial
And them pull a docker image ‘tutorial’ by user ‘learn’
sudo docker pull learn/tutorial
List all docker images present in the system
sudo docker images
Run a docker image, and execute command ‘echo “hello world”’ in the docker container created out of that image
sudo docker run ubuntu:14.04 echo "hello world"
Container information is stored in /var/lib/docker
If you run the above command multiple times, it will create a new container each time.
To know the ID of the last container, run
sudo docker ps -l
To list all the running containers
sudo docker ps
Note that the above command will not show the container we last run, because the container which we ran last time terminated just after it finished executing echo command.
Create a new docker image by name <yourname>/echo by ‘committing’ the last
container which you ran
sudo docker commit <container ID> <yourname>/echo
Now running sudo docker images will list you two images instead of one
Now you can run this new docker container like this:
sudo docker run <yourname>/echo ls -alrth
If we installed something, or created a file in the old container, it will be visible now in this container too.
Get more information about a docker image or a running container:
sudo docker inspect <yourname>/echo
To push docker image to docker repository
sudo docker push <yourname>/echo
To download ubuntu Trusty base image if not present locally, and open a shell session into it
sudo docker run -t -i ubuntu:14.04 /bin/bash
-i i.e. –interactive=false, keeps STDIN open even if not attached
-t i.e. –tty=false allocates a pseudo tty
Don't worry what these mean. If you add these options, you'll see that
you already get logged in into the container shell, and the container
only dies off once you exit from that session (usually by writing exit
or pressing CTRL + D.
To remove an image:
sudo docker rmi learn/tutorial
Things not covered in this tutorial:
- Create your own custom docker images and share with other people: https://docs.docker.com/userguide/dockerimages/
Cheers!