Docker Desktop 4.21: Support for new Wasm runtimes, Docker Init support for Rust, Docker Scout Dashboard enhancements | Docker

Docker Desktop 4.21 is now available and includes Docker Init support for Rust, new Wasm runtimes support, enhancements to Docker Scout dashboards, Builds view (Beta), performance and filesystem enhancements to Docker Desktop on macOS, and more. Docker Desktop in 4.21 also uses substantially less memory, allowing developers to run more applications simultaneously on their machines without relying on swap. 

Added support for new Wasm runtimes

Docker Desktop 4.21 now has added support for the following Wasm runtimes: Slight, Spin, and Wasmtime. These runtimes can be downloaded on demand when the containerd image store is enabled. The following steps outline the process:

1. In Docker Desktop, navigate to the settings by clicking the gear icon.
2. Select the Features in development tab.
3. Check the boxes for Use containerd for pulling and storing images and Enable Wasm.
4. Select Apply & restart.
5. When prompted for Wasm Runtimes Installation, select Install.
6. After installation, these runtimes can be used to run Wasm workloads locally with the corresponding flags, for example:
   --runtime=io.containerd.spin.v1 --platform=wasi/wasm32

Docker Init (Beta) added support for Rust 

In the 4.21 release, we’ve added Rust server support to Docker Init. Docker Init is a CLI command in beta that simplifies the process of adding Docker to a project. (Learn more about Docker Init in our blog post: Docker Init: Initialize Dockerfiles and Compose files with a single CLI command.)

You can try Docker Init with Rust by updating to the latest version of Docker Desktop and typing docker init in the command line while inside a target project folder. 

The Docker team is working on adding more languages and frameworks for this command, including Java and .Net. Let us know if you want us to support a specific language or framework. We welcome feedback as we continue to develop and improve Docker Init (Beta).

Docker Scout dashboard enhancements 

The Docker Scout Dashboard helps you share the analysis of images in an organization with your team. Developers can now see an overview of their security status across all their images from both Docker Hub and Artifactory (more registry integrations coming soon) and get remediation advice at their fingertips. Docker Scout analysis helps team members in roles such as security, compliance, and operations to know what vulnerabilities and issues they need to focus on.

Visit the Docker Scout vulnerability dashboard to get end-to-end observability into your supply chain. 

Docker Buildx v0.11

Docker Buildx component has been updated to a new version, enabling many new features. For example, you can now load multi-platform images into the Docker image store when containerd image store is enabled.

The buildx bake command now supports matrix builds, allowing defining multiple configurations of the same build target that can all be built together.

There are also multiple new experimental commands for better debugging support for your builds. Read more from the release changelog. 

Builds (Beta)

Docker Desktop 4.21 includes our Builds view beta release. Builds view gives you visibility into the active builds currently running on your system and enables analysis and debugging of your completed builds.

All builds started with docker build or docker buildx build commands will automatically appear in the Builds view. From there, you can inspect all the properties of a build invocation, including timing information, build cache usage, Dockerfile source, etc. Builds view also provides you full access to all of the logs and properties of individual build steps.

If you are working with multiple Buildx builder instances (for example, running builds inside a Docker container or Kubernetes cluster), Builds view include a new Builders settings view to make it even easier to manage additional builders or set default builder instances.

Builds view is currently in beta as we are continuing to improve them. To enable them, go to Settings > Features in development > Turn on Builds view.

Faster startup and file sharing for macOS 

Launching Docker Desktop on Apple Silicon Macs is at least 25% quicker in 4.21 compared to previous Docker Desktop versions. Previously the start time would scale linearly with the amount of memory allocated to Docker, which meant that users with higher-spec Macs would experience slower startup. This bug has been fixed and now Docker starts in four seconds on Apple Silicon. 

Docker Desktop 4.21 uses VirtioFS by default on macOS 12.5+, which provides substantial performance gains when sharing host files with containers (for example, via docker run -v). The time taken to build the Redis engine drops from seven minutes on Docker Desktop 4.20 to only two minutes on Docker Desktop 4.21, for example.

Conclusion

Upgrade now to explore what’s new in the 4.21 release of Docker Desktop. Do you have feedback? Leave feedback on our public GitHub roadmap and let us know what else you’d like to see.

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