Orientation and setup
Estimated reading time: 4 minutes
Update to the Docker Desktop terms
Professional use of Docker Desktop in large organizations (more than 250 employees or more than $10 million in annual revenue) requires users to have a paid Docker subscription. While the effective date of these terms is August 31, 2021, there is a grace period until January 31, 2022, for those that require a paid subscription. For more information, see the blog Docker is Updating and Extending Our Product Subscriptions.
Welcome! We are excited that you want to learn Docker.
This page contains step-by-step instructions on how to get started with Docker. In this tutorial, you’ll learn how to:
- Build and run an image as a container
- Share images using Docker Hub
- Deploy Docker applications using multiple containers with a database
- Running applications using Docker Compose
In addition, you’ll also learn about the best practices for building images, including instructions on how to scan your images for security vulnerabilities.
If you are looking for information on how to containerize an application using your favorite language, see Language-specific getting started guides.
We also recommend the video walkthrough from DockerCon 2020.
Download and install Docker
This tutorial assumes you have a current version of Docker installed on your machine. If you do not have Docker installed, choose your preferred operating system below to download Docker:
Start the tutorial
If you’ve already run the command to get started with the tutorial, congratulations! If not, open a command prompt or bash window, and run the command:
$ docker run -d -p 80:80 docker/getting-started
You’ll notice a few flags being used. Here’s some more info on them:
-d- run the container in detached mode (in the background)
-p 80:80- map port 80 of the host to port 80 in the container
docker/getting-started- the image to use
You can combine single character flags to shorten the full command. As an example, the command above could be written as:
$ docker run -dp 80:80 docker/getting-started
The Docker Dashboard
Before going too far, we want to highlight the Docker Dashboard, which gives you a quick view of the containers running on your machine. The Docker Dashboard is available for Mac and Windows. It gives you quick access to container logs, lets you get a shell inside the container, and lets you easily manage container lifecycle (stop, remove, etc.).
To access the dashboard, follow the instructions in the
Docker Desktop manual. If you open the dashboard
now, you will see this tutorial running! The container name (
jolly_bouman below) is a
randomly created name. So, you’ll most likely have a different name.
What is a container?
Now that you’ve run a container, what is a container? Simply put, a container is a sandboxed process on your machine that is isolated from all other processes on the host machine. That isolation leverages kernel namespaces and cgroups, features that have been in Linux for a long time. Docker has worked to make these capabilities approachable and easy to use. To summarize, a container:
- is a runnable instance of an image. You can create, start, stop, move, or delete a container using the DockerAPI or CLI.
- can be run on local machines, virtual machines or deployed to the cloud.
- is portable (can be run on any OS)
- Containers are isolated from each other and run their own software, binaries, and configurations.
Creating containers from scratch
If you’d like to see how containers are built from scratch, Liz Rice from Aqua Security has a fantastic talk in which she creates a container from scratch in Go. While the talk does not go into networking, using images for the filesystem, and other advanced topics, it gives a fantastic deep dive into how things are working.
What is a container image?
When running a container, it uses an isolated filesystem. This custom filesystem is provided by a container image. Since the image contains the container’s filesystem, it must contain everything needed to run an application - all dependencies, configuration, scripts, binaries, etc. The image also contains other configuration for the container, such as environment variables, a default command to run, and other metadata.
We’ll dive deeper into images later on, covering topics such as layering, best practices, and more.
If you’re familiar with
chroot, think of a container as an extended version of
chroot. The filesystem is simply coming from the image. But, a container adds additional isolation not available when simply using chroot.
Refer to the following topics for further documentation on all CLI commands used in this article:get started, setup, orientation, quickstart, intro, concepts, containers, docker desktop