rbannist / containersonazure_simpledocker_arcadia

A simple intro to Docker

Step 1 - Install Docker:

This has been completed in advance. Access your 'Docker' VM using Guacamole.

Images key:

Line Colour	What is it showing?
Purple	The path of your access to various machines
Black	Console commands and locations
Dark Blue	Docker control plane
Green	Docker actions/events
Red	Standard 'Data Plane' comms
Yellow	Network (logical)

Docker-specific key:

Character	Item
"i:"	Image
"c:"	Container (from image)
"l:"	Writeable union filesystem layer atop image

Step 2 - Run a container using the 'Hello World' image:

sudo docker run hello-world

Note the "Unable to find image 'hello-world:latest' locally" and the subsequent "Pulling" message.

Step 3 - Pull down an image from Docker Hub before running a container:

sudo docker pull ubuntu:latest

Step 4 - Run a container based on the image pulled down in Step 3 and attach:

sudo docker run -it ubuntu:latest /bin/bash

Step 5 - Exit the container and clear up:

exit

or

'Ctrl+d'

sudo docker ps -a

sudo docker rm <idofcontainercopiedfromlastoutput>

Step 6 - Run another container based on the image pulled down in Step 3, attach to it, install Nginx, test the service, and exit:

On your 'Docker VM':

ifconfig -a

Note down the IP address on 'Eth0'.

sudo docker run -it -p 80:80 --net=host ubuntu /bin/bash

On the container:

apt-get update

apt-get install nano -y

apt-get install nginx -y

nano /var/www/html/index.nginx-debian.html

Edit the html file in any way you see fit

'Ctrl+o', 'Ctrl+x' to save and exit nano

Start nginx:

/etc/init.d/nginx start

On your 'Mgmt VM' (Windows), browse to:

http://<dockervmipadress>

You should see an Nginx welcome page with your edits.

Step 7 - Build a new image based on the addition of a new layer that was added in Step 6 atop the original 'Ubuntu' image:

Back on the 'Docker VM':

sudo docker ps -a

Create a new image based on the ubuntu image + the changes made:

sudo docker commit <idofcontainerlistedinthelastoutput> <yourfirstname>/nginx

Remove the container that we used to build a new image:

sudo docker rm <idofcontainerlistedinthelastoutput>

Run a new container based on the image created above and start the nginx service in the background:

sudo docker run -d -p 80:80 --net=host <yourfirstname>/nginx nginx -g 'daemon off;'

See the '-d' switch which runs the container in the background (i.e. you'll remain at the prompt provided by your 'Docker VM' after seeing an ID printed to screen which is the new container's ID).

On 'Mgmt VM', browse to:

http://<dockervmipadress>

You should see the page that you edited again.

Note. The new image is currently only stored locally as it's not been pushed to a registry such as Docker Hub or Azure Container Registry. This would mean a lack of 'portability'.

Clear up:

sudo docker ps

sudo docker stop <idofcontainerlistedinthelastoutput>

sudo docker rm <idofcontainerlistedinthelastoutput>

Step 8 - Inspect the layers of our image:

sudo docker history <yourfirstname>/nginx

See the /bin/bash layer at the top that's added ~96.5MB.

Step 9 - Declaratively template the process that we've just run through using a 'Dockerfile':

On your 'Docker VM':

sudo mkdir nginxdockerfile

cd nginxdockerfile

sudo nano Dockerfile

Type in:

FROM ubuntu 

RUN apt-get update

RUN apt-get install -y nginx

RUN echo "\ndaemon off;" >> /etc/nginx/nginx.conf

CMD ["nginx"]

EXPOSE 80

'Ctrl+o', 'Ctrl+x' to save and exit.

Perform a build using the Dockerfile just created:

sudo docker build -t <yourfirstname>/nginx2 .

Run a container using the new image:

sudo docker run -d -p 80:80 --net=host <yourfirstname>/nginx2

Test on 'Mgmt VM' by browsing to:

http://<dockervmipadress>

Step 10 - Declaratively template a multi-container template using Docker Compose

Richard to demonstrate.