Introduction to Docker

A hands-on introduction to using Docker. By the end of the workshop you should be able to run Docker containers, build Docker images interactively, and use a Dockerfile to create a Docker image with code.

It covers working with Docker images and containers. It does not cover Docker installation, although if you can create an Ubuntu VM there is a script below that will install the required software.

Security Tools

We don't look into security in this workshop, and there are some shortcuts that we take that are acceptable for sample code that won't work for a serious deployment.

If you want some tools to tidy up and secure your containers better, here are a few to consider:

• Anchore Grype- demo
• Aqua Security Trivy- demo
• Checkov by Bridgecrew- demo

There is a demonstration of identifying the Spring4Shell vulnerability using Trivy and Grype as well. There is a longer discussion with more Kubernetes and container security tools as a meetup and similar slides.

Prerequisites

To participate, you need to have a workstation with Docker installed and available.

Windows

On Windows, having Docker Desktop installed with the Windows Subsystem for Linux will suffice. Ubuntu is the preferred operating system.

The commands are written out for a bash or similar shell. If you use PowerShell, you'll need to change how some of the commands are written.

• The line continuation character in PowerShell is a backtick (`) instead of a backslash (\).
• The current directory is ${pwd} instead of ${PWD}.
• The user's home directory is $HOME instead of ${HOME}.

So in Lesson 3, for example,

docker run -it --rm --volume ${PWD}:/usr/src/maven --volume ${HOME}/.m2:/root/.m2 \
    --workdir /usr/src/maven maven:3.8.6-eclipse-temurin-17 mvn clean package

in PowerShell becomes

docker run -it --rm --volume ${pwd}:/usr/src/maven --volume $HOME/.m2:/root/.m2 `
    --workdir /usr/src/maven maven:3.8.6-eclipse-temurin-17 mvn clean package

AWS Cloud9

In the cloud, using an AWS Cloud9 instance is the easiest environment to prepare. A default, free-tier t2.micro (1 GiB RAM + 1 vCPU) instance with 10GiB of storage will suffice for the first 4 lessons. You'll need at least a t3.medium or t3a.medium (4 GiB RAM + 2 vCPU) instance with 16GiB of storage for Lesson 5 to handle all the images and containers that run in that lesson.

Once you start a Cloud9 instance and connect, follow the Resize an Amazon EBS volume used by an environment instructions to bump the storage to at least 16 GiB.

Then, install the Compose CLI plugin for Docker.

$ DOCKER_CONFIG=${DOCKER_CONFIG:-$HOME/.docker}
$ mkdir -p ${DOCKER_CONFIG}/cli-plugins
$ curl -SL https://github.com/docker/compose/releases/download/v2.14.0/docker-compose-linux-x86_64 -o ${DOCKER_CONFIG}/cli-plugins/docker-compose
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100 42.8M  100 42.8M    0     0  9600k      0  0:00:04  0:00:04 --:--:--  9.8M
$ chmod +x ${DOCKER_CONFIG}/cli-plugins/docker-compose
$ docker compose version
Docker Compose version v2.14.0

Finally, open TCP ports 80, 8080, and 4444 for external traffic. In the Cloud9 IDE, click on the circle with you first initial in the upper-right hand corner of the screen and choose Manage EC2 Instance.

Click on the instance ID (e.g., i-006e1ded29b3af4c2), then the Security tab, and then on the security groups link (e.g., sg-02dca994b48a154a3). Then, on the Inbound rules tab, select the Edit inbound rules button. Add a rule for each of the 3 ports (80, 8080, 4444) from Anywhere- IPv4 and click Save rules.

Finally, back on the Cloud9 terminal, find your public IP address.

$ curl http://169.254.169.254/latest/meta-data/public-ipv4
18.224.95.18

AWS EC2 Ubuntu

If you want to use your own cloud image, set up an instance in AWS with a current Ubuntu AMI and then copy the install-docker.sh script to the system and run it as root (e.g., sudo bash ./install-docker.sh). On AWS, a t2.micro (1 GiB RAM + 1 vCPU) or similar is probably enough for the Docker lessons. The comments in the script explain the networking/security group requirements.

To complete the Docker Compose lesson (Lesson 5), you'll need the Compose CLI plugin for Docker installed. The install-docker.sh script handles that. The cloud instance will need to be at least a t3.medium or t3a.medium (4 GiB RAM + 2 vCPU) instance with 16 GiB of storage to handle all the images and containers that run in that lesson.

Final check

Check that you are ready by running docker from the command line.

$ docker --version
Docker version 20.10.17, build 100c701

The exact version and build number are not critical to this workshop.

If the command works and you get a response similar to above, you are ready to proceed with Lesson 1- Our First Containers.

Good luck!