Docker workshop

In front of you there is a laptop with Docker toolbox installed. Use Putty to make connection to your running docker host (docker@192.168.99.100). During the following exercises, you will learn to get along with Docker in the basic way of working, and be able to deploy small containers. If you have any questions, feel free to ask.

Link to putty: https://the.earth.li/~sgtatham/putty/latest/x86/putty.exe

Link to userguide of Docker: https://docs.docker.com/engine/userguide/containers/usingdocker/

Basics

First, learn to get started with Docker after our presentation. We are going to deploy a Busybox container on our docker environment. Busybox is a small linux environment and a sandbox to play with.

docker pull busybox

$ docker pull busybox
Using default tag: latest
latest: Pulling from library/busybox

This way, we will download the image to our docker machine so its ready for use in a container. Check if the image is correctly downloaded.

docker images

$ docker images
REPOSITORY                TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
busybox                   latest              sha256:47bcc        10 weeks ago        1.113 MB

Ok, we are fine. Now, lets try and start a container with this image, and use hello world as echo command:

docker run busybox echo "hello world"

Check your output:

$ docker run busybox echo "hello world"
hello world

Now, check the status of the containers with the docker ps command

docker ps

What do you see ? Right, nothing. Thats because the container was executed with the hello world command, and then exited. Add the "-a" flag.

docker ps -a

Should be somehow the following output:

$ docker ps -a
CONTAINER ID        IMAGE                     COMMAND                CREATED             STATUS                     PORTS               NAMES
901765e0ec64        busybox                   "echo 'hello world'"   2 minutes ago       Exited (0) 2 minutes ago                       backstabbing_liskov

This verifies that the container has been shutdown. But, we wanna do more in the container, besides and echo command. Run in it as following:

docker run -it busybox sh

With this command, we are starting a new busybox container with an interactive shell so we can do some commands. Use the "ls" command to list everything inside the root directory. You should be seeing output with folders named as "bin", "dev", etc...

Create a new file in the container called "test.txt":

vi test.txt

Press "i" to insert some text, and when you are done, press escape and type :wq. This will save the file and creates it in the root directory of the busybox container.

/ # ls
bin       etc       proc      sys       tmp       var
dev       home      root      test.txt  usr

Now, let's show you what happens when we start a container with the same image again.

docker run -it busybox sh

When you are in prompt, list all files and folders in the root directory again. What do you notice after you created test.txt last time ?

Everytime you start a new container, all changes will be gone. Unless you commit your work to a Docker image and repository, all the stuff you added to your container will be lost. The power of docker in this matter is being able to quickly deploy containers based on an image and repo you are using.

Play around a bit with the busybox container, then leave it by typing exit. You know how to basicly deploy a container now, let's go a little bit more indept.

NOTE: If you are starting a container with the logging visible, don't exit it. Just open a new Putty session to the docker container to see your container running and continue doing docker commands.

Deploying a website

Everybody knows wordpress. To show you, for example, how easy it is to deploy a new wordpress website, we will use the power of our docker host. Let's go !

Wordpress usually works with a MySQL database. This database will be deployed along with the Wordpress container. Use the following command:

docker run --name mysqlqnh -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:latest

--name = name of the container
-e = entry in the configuration of the container
-d = imagename including the latest tag of the application

You will not have the MySQL image yet, but Docker will download this one from the hub for you. When it is ready, confirm that the MySQL container is up and running:

docker ps -a

474a177f6df8        mysql:latest              "docker-entrypoint.sh"   27 minutes ago      Up 27 minutes               3306/tcp                       mysqlqnh

Your MySQL container is running. Now, let's deploy our wordpress website with the following command:

docker run --name WP-qnh -p 0.0.0.0:8890:80 --link mysqlqnh:mysql -d wordpress

--name = name of the container
-p = Ports used in- and outside the container. The last port is the application port, the first port is the runtime port. This port will be used to approach the container with, i.e., your browser.
--link = linking the wordpress container to the MySQL database
-d = image to be used

Now, check if your wordpress container is running. Go to your webbrowser and use the IP of your docker host (normally 192.168.99.100) and use the first port stated in the command before (8890)

http://192.168.99.100:8890

docker@default:~$ docker ps -a
CONTAINER ID        IMAGE                     COMMAND                  CREATED             STATUS                      PORTS                          NAMES
8c6fca021f6a        wordpress                 "/entrypoint.sh apach"   4 seconds ago       Up 2 seconds                0.0.0.0:8890->80/tcp           some-wordpress
474a177f6df8        mysql:latest              "docker-entrypoint.sh"   27 minutes ago      Up 27 minutes               3306/tcp                       mysqlqnh

If everything went correctly, the installation of Wordpress will pop up. Deploy your website to check if everything is fine.

If you are in for it, deploy another Wordpress website on an other port. You will see you will have two websites on 1 machine.

Challenge !

Try to deploy a

• Gitlab environment
• Kibana monitoring

And show us what you got from this course !