Overview of the Docker workshop

This 45-minute workshop contains step-by-step instructions on how to get started with Docker. This workshop shows you how to:

• Build and run an image as a container.
• Share images using Docker Hub.
• Deploy Docker applications using multiple containers with a database.
• Run applications using Docker Compose.

Note

For a quick introduction to Docker and the benefits of containerizing your applications, see Getting started.

What is a container?

A container is a sandboxed process running on a host machine that is isolated from all other processes running on that host machine. That isolation leverages kernel namespaces and cgroups, features that have been in Linux for a long time. Docker makes 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 Docker API or CLI.
• Can be run on local machines, virtual machines, or deployed to the cloud.
• Is portable (and can be run on any OS).
• Is isolated from other containers and runs its own software, binaries, configurations, etc.

If you're familiar with chroot, then think of a container as an extended version of chroot. The filesystem comes from the image. However, a container adds additional isolation not available when using chroot.

What is an image?

A running container uses an isolated filesystem. This isolated filesystem is provided by an image, and the image must contain everything needed to run an application - all dependencies, configurations, scripts, binaries, etc. The image also contains other configurations for the container, such as environment variables, a default command to run, and other metadata.

Next steps

In this section, you learned about containers and images.

Next, you'll containerize a simple application and get hands-on with the concepts.