This document outlines an agenda for a two-day workshop on containers and Docker. Day 1 covers virtualization theory and hands-on labs with VirtualBox. Day 2 focuses on containers theory, Docker, and hands-on Docker labs. The document explains key Docker concepts like images, the Dockerfile for building images, layers, networking, and orchestration. It provides instructions for several hands-on Docker labs including running cowsay in a container, pulling an existing image, building a custom image that runs cowsay with fortunes, and publishing the custom image to Docker Hub.

1. Containers + Docker
workshop
Davide Pelosi
Enterprise Software Advisor
davide.pelosi@dpstudio.eu

2. Agenda
Day 1
● Virtualization
○ Theory
○ VirtualBox
○ Hands-on Labs
Day 2
● Containers
○ Theory
○ Docker
○ Hands-on Labs

3. Virtual Machines VS Containers
Source for image: https://www.docker.com/what-container

4. VM and Containers used together
Source for image: https://www.docker.com/what-container
Containers Only Containers working into VMs

5. Container Image
● A container image is a lightweight, stand-alone, executable package of a
piece of software
● Includes everything needed to run it: code, runtime, system tools, system
libraries, settings
● Containers isolate software from its surroundings, for example differences
between development and staging environments
● Help reduce conflicts between teams running different software on the same
infrastructure.

6. Containers Orchestration
● Goes beyond the management of
individual containers
● Treats the entire cluster as a single
deployment target
● Automates application management
○ initial placement, scheduling, deployment,
update, health monitoring, scaling and
failover

7. Containers Orchestrator Features
● Configuration using a standard schema
○ YAML or JSON
○ Contains repositories, networking, storage
○ Different configurations for different env
● Defining Rules
○ Affinity and constraints placement rules
○ Workload rules
● Provisioning and scheduling
○ Container-provisioning API
○ Infrastructure APIs specific to the host
environment.
● Monitoring
○ Track and monitor the health of containers
and hosts
○ Relocate the containers in the event of
host failure

8. Containers Landscape

9. Docker - Command Line Interface (CLI)
➢ docker ps
○ Lists all running containers
○ shows information including their ID, name, base image name, and port forwarding
➢ docker build
○ Processes the Dockerfile and creates a new container
➢ docker pull [image name]
○ Pulls the container image from the remote repository and stores the definition locally
➢ docker run
○ Starts a container based on a local or remote (e.g. DockerHub) container definition
➢ docker push
○ Publishes a built container definition to a repository, typically DockerHub.

10. Docker - Dockerfile
● Script composed of commands
● Automatically perform actions on a base image
○ FROM ubuntu
● Main commands (instructions)
○ ADD - copies files from the host into the container's filesystem
○ CMD - executes a specific command when a container is instantiated
○ RUN - runs a command to build the image (forming another layer on top of the previous one)
○ EXPOSE - associates a port to enable networking between the running process inside the
container and the outside world (EXPOSE 8080)
○ ENTRYPOINT - sets the concrete default application that is used
○ ENV - sets the environment variables
○ VOLUME - enables access from container to a directory on the host machine

11. Docker - Image Layers
● An image references a list of RO layers
● A layer represents filesystem differences
● The Docker storage driver provides a
single unified view
● When creating a new container a new,
thin, writable layer is added on top of the
underlying stack (container layer)
● Changes to the running container are
written to this thin writable container layer

12. Docker - Networking
● When you install Docker, it creates three networks (> docker network ls)
○ Bridged (attached by default)
■ see it using ifconfig → docker0
■ containers communicate with each other by IP address
○ None (not configurable)
■ container specific
■ lacks a network interface
○ Host (not configurable)
■ adds a container on the host’s network stack
■ no isolation between the host machine and the container

13. Lab 0 - Play with cowsay and fortunes
1. Install cowsay
○ $ sudo apt-get update
○ $ sudo apt-get install cowsay
2. Run cowsay
○ $ cowsay 'hello world!!'
3. Install fortunes
○ $ sudo apt-get install fortune
4. Run fortune
○ $ fortune
5. Run a smarter cowsay
○ $ fortune -a | cowsay
Let’s play in our VM!

14. Lab 1 - Install and test docker
Now let’s make the same in a docker container!!
1. Install docker
○ $ sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
○ $ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
○ $ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial
stable"
○ $ sudo apt-get update
○ $ sudo apt-get install docker-ce
○ $ sudo groupadd docker
○ $ sudo usermod -aG docker $USER
2. Test docker working
○ $ docker run hello-world
○ $ docker run -it ubuntu bash

15. Lab 2 - Download and start an existing image
1. Look for a whalesay image
○ https://hub.docker.com/explore
○ Search for whalesay (docker/whalesay)
○ Click and read the image description
2. Download the whalesay image
○ $ docker pull docker/whalesay
3. Check that the image is present into the
local docker repository
○ $ docker images
○ The docker/whales image should be listed
4. Run the whalesay image
○ $ docker run docker/whalesay cowsay
'hello world!!'
5. Check for running images
○ $ docker ps
○ there are no running images

16. Lab 3 - Create our smarter docker image
1. Prepare the working folder
○ $ mkdir mywhale
○ $ cd mywhale
2. Create the Dockerfile
○ $ gedit Dockerfile
3. Build the docker image
○ $ docker build -t my-docker-whale .
4. Check for the new image
○ $ docker images
5. Run the custom whalesay image
○ docker run my-docker-whale
Dockerfile
#inherit from docker/whalesay image
FROM docker/whalesay:latest
#install fortunes application
RUN apt-get -y update && apt-get install -y fortunes
#run cowsay using as input the fortune output
CMD /usr/games/fortune -a | cowsay

17. Lab 4 - Make your image publicly available
1. Create an account in docker hub (https://hub.docker.com)
2. Create a tag for the new image
○ $ docker tag <image ID> <accountname>/my-docker-whale:latest
3. Login into docker hub with your user account
○ $ docker login --username=<accountname>
4. Upload the new image into your user account
○ $ docker push <accountname>/my-docker-whale
5. Remove the local image
○ $ docker rmi -f <image ID>
6. Run the new image
○ $ docker run accountname/my-docker-whale
○ Will download the image from the docker hub

18. The end!
Davide Pelosi
davide.pelosi@dpstudio.eu