At DockerCon 2022, Docker announced a way for developers to tap into Docker Desktop and extend its functionality using a new Extension SDK. Additionally, Docker Desktop is finally landing on Linux, providing the same experience available on macOS and Windows.
Packaged as containers, extensions aim to allow developers to integrate 3rd party tools in Docker Desktop and simplify their workflows. A number of extensions are already available in a newly launched marketplace which aims to highlight notable extensions. For example, RedHat developed an extension to deploy Docker images to OpenShift. Another extension, developed by VMware, makes it possible deploy to a VMware Tanzu Community Edition based Kubernetes cluster.
Security is an area where extensions also seem to fit very well, with several vendors, including Snyk, Anchore, JFrog and others, offering vulnerability scanners and analyzers. Extensions are not limited to just deployment and security, though. A Disk Usage extension built by Docker provides a way to analyze and manage disk usage, while Log Explorer enables viewing and searching logs across containers.
Since extensions are just containers, they can be distributed and installed just like any other image, so neither the Marketplace nor Docker Hub are strictly required.
To make it easier for developers to create extensions, Docker has introduced a specific SDK and provided a number of tutorials. You can create extensions that have a UI as well as backend extensions.
Along with extensions, Docker has announced the availability of Docker Desktop for Linux. While Docker Desktop is required to run Docker Engine on macOS and Windows, it is not strictly so on Linux, since Docker Engine sits directly on its kernel. For macOS and Windows, Docker Desktop includes in fact a lightweight Linux virtual machine enabling the engine to run. It is interesting to note that Docker is following the same approach on Linux as on other OSes by running the Docker engine inside a VM. In private conversation with InfoQ, Docker sources explained that this is aimed to standardise user experience across OSes.
Docker lists several reasons why you would want to use Docker Desktop on Linux, including out-of-the-box seamless support for Kubernetes integration and ease of management through its UI. With the introduction of Extensions, this counts too as a possible reason for using Docker Desktop for Linux. In spite of these benefits, developers wishing to do so can continue to use Docker Engine on Linux.
Docker Desktop for Linux is generally available on several distributions, including Debian, Fedora, Ubuntu, and Arch. Docker Extensions on the contrary, are still considered in beta. You can try them out using Docker Desktop 4.8.0+.
NOTE: This article was amended on May 15th to include the mention that Docker Desktop for Linux runs on top of a VM.