Installing Docker
Overview
Teaching: 10 min
Exercises: 15 minQuestions
What equipment do I need?
How do I install Docker?
How do I test my installation?
What are the main Docker concepts and commands I need to know?
Objectives
Install Docker on your machine
Understand the most basic concepts about images and containers
Installing Docker is relatively straightforward, particularly because of the excellent documentation they provide. Still you want to set aside some time to do it properly and test it out.
Installing
Go to the offical Docker site and their installation instructions to install Docker for your operating system.
We see no need to go beyond the documentation they provide so we leave it up to you to follow their installation procedure.
In the episodes of this lesson that follow, we assume that Windows users have WSL2 activated with a Linux bash shell (e.g. Ubuntu) and Docker Desktop installed. All commands indicated with “bash” are expected to be typed in this Linux shell.
Note that WSL2 can take around an hour to install.
Testing
As you walk through their documentation, you will eventually come to a point where you will
run a very simple test, usually involving their hello-world
container.
You can find their documentation for this step here.
Testing their code can be summed up by the ability to run (without generating any errors) the following commands.
docker --version
docker run hello-world
Images and Containers
As it was mentioned above, there is ample documentation provided by Docker official sites. However, there are a couple of concepts that are crucial for the sake of using the container technology with CMS open data: container images and containers.
One can think of the container image as the main ingredients for preparing a dish, and the final dish as the container itself. You can prepare many dishes (containers) based on the same ingredients (container image). Images can exist without containers, whereas a container needs to run an image to exist. Therefore, containers are dependent on images and use them to construct a run-time environment and run an application.
The final dish, for us, is a container that can be thought of as an isolated machine (running on the host machine) with mostly its own operating system and the adequate software and run-time environment to process CMS open data.
Docker provides the ability to create, build and/or modify images, which can then be used to create containers. We will not use this aspect of the technology because, as you will see later, we will use an already-built and ready-to-use image in order to create our needed container.
Commands Cheatsheet
There are many Docker commands that can be executed for different tasks. However, the most useful for our purposes are the following. We will show some usage examples for some of these commands later. Feel free to explore other commands.
- Download image:
docker pull <image>
- List images:
docker image ls
- Remove images
docker image rm <image>
or
docker rmi <image>
- List containers
docker container ls -a
or
docker ps -a
The
-a
option shows all containers (default shows just those running) - Remove containers
docker container rm <container>
or
docker rm <container>
- Create and start a container based on a specific image
docker run [options] <image>
This command will be used later to create our CMS open data container.
- Stop a running container
docker stop <container>
- Attach a running (but detached) container
docker attach <container>
- Start and attach a container that was stopped
docker start -i <container>
- Copy files in or out of a container_run
docker cp <container>:<path> <local path> docker cp <local path> <container>:<path>
Key Points
For up-to-date details for installing Docker, the official documentation is the best bet.
Make sure you were able to download and run Docker’s
hello-world
example.The concepts of image and container, plus the knowledge of certain Dockers commands, is all that is needed to start using CMS open data