Docker survival kit

WARNING!!!!!! Straight from the Mad Scientist!!

Part 3

Let’s finish this up! One of the biggest issues I had learning Docker was when you use $ sudo docker run -i -t xod442/lamp /bin/bash to get a terminal session running on a docker image, you spawn a new container id. THE CHANGES YOU ARE MAKING DO NOT EFFECT THE ORIGINAL DOCKER IMAGE!!!! They are only relevant to the container id you are working in. Once you are finished with the changes to the container, you will need to commit them to a NEW docker image $ sudo docker commit 90934ee6cf3f xod442/new_image_name. This is a bit tricky at first but once the light bulb comes on you’ll think you’re a freaking genius!

Now lets say the docker image we created is a LAMP server. We want to run the LAMP server and have it stay up until we decide to stop it. I found this command works well. $sudo docker run -d -p 80:80 xod442/macfind /usr/sbin/apache2ctl -D FOREGROUND. In this command we are binding the local host interface to port 80 and the docker interface to port 80 as well. To test if your LAMP is up point a browser to http://dockerhost (use the IP address of your docker host)

Another way to verify that our LAMP server is up and running is to look at the docker processes. $ sudo docker ps -a will display all the containers we have ever started and what their operational state is. In the diagram below you can see that container 90934ee6cf3f is UP and running on port 80 and 5a52ff424b65 exited about an hour ago.


Have you noticed that names? Like cocky_brattain? If you don’t specify a name when running or starting a container, docker will make one up. You will notice each one is unique to your host. You can use your own names by using $ sudo docker run –name (containerName) -i -t ubuntu /bin/bash. Now when you look at the docker processes, you can easily identify your container for the others.

Finally here is a short list of commands that I use often. Copy them down and make your own docker cheat sheet.

sudo docker run –name (containerName) -i -t ubuntu /bin/bash
-Start a docker container, give it a name, pull ubuntu from dockerhub, load into container and offer the bash prompt.

exit – exits the container

sudo docker ps -a – Shows what containers are active and recently stopped. Here you can find the container ID

sudo docker start (containerId) – Starts the container

sudo docker attach lampster – attaches to the console of the container by name

sudo docker exec -i -t containerid bash – gives you bash on a running container

sudo docker rm $(sudo docker ps -a -q) -Removes all containers from your workspace (Danger Will Robinson!!)

sudo docker rmi $(sudo docker images -q) – Removes all images from work space (Danger Will Robinson!!)

sudo docker login – Allows you to login to dockerhub

sudo docker search (Keyword) – Allows you to search the dockerhub for pre-built container

sudo docker pull (owner/ImageName) – Get container from dockerhub

sudo docker commit (containerId) (owner/ImageName) – Builds a new Image from a container

sudo docker push (owner/ImageName) – Put Images on your dockerhub space

Hopefully this three part blog has stirred up some interest in diving into the world of containerization. It is by far only a limited look into this technology and I urge you to setup your own docker workstation and explore!.

Finally, there is talk from Microsoft about working with Docker and implementing containers in Windows. When this is pervasive, keep in mind that if you build a docker container on a windows platform, it will not be able to run on top of a linux docker server. Kind of goes without saying ……but there are those of you reading this now who are not so string with the force!! You know who you are!

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