Microsoft Ships WSL Containers 1.0 Without Compose Support

Microsoft made WSL containers generally available on Sept. 29 in WSL 3.0.1, giving Windows a built-in command, wslc.exe, for building and running Linux containers without installing a separate engine. It does not yet read a compose.yaml file, which is the part of most real container workflows that holds the project together.

Logan Iyer, Microsoft's corporate vice president for Windows Platform and Developer, announced the release on the Windows Developer Blog. "Linux containers are central to modern development, from cloud-native applications to AI workloads," the post says. The WSL 3.0.1 release page on GitHub dates the build to the same day and removes the preview label from the feature.

What installing it involves

The install step is wsl --update, according to heise, which also reports that WSL 3.0.1 can be taken from GitHub directly. Nothing else needs to be set up before wslc.exe runs. A built-in alias, container.exe, exists for people who already type container commands from memory.

The Microsoft post does not say which Windows versions are supported, and it does not say whether the commands match Docker's flag for flag. A team planning a rollout has to test that rather than read it.

What the preview had and the 1.0 build adds

The post lists the commands that arrived between the public preview and general availability. Most of them are the plumbing a developer reaches for on the second day of using a tool.

Command or option	What it does
wslc container restart	Restarts a container
wslc container cp	Copies files in and out
wslc system info	Reports the state of the container environment
wslc events	Streams container events live
wslc network connect / disconnect	Attaches and detaches a container from a network

Health checks, a --mount option, configurable storage paths and a --stop-timeout flag also shipped. Microsoft said file access from Linux to Windows folders is up to 2x faster, though the post does not name the baseline or the workload it measured.

heise puts the speedup down to virtiofs, a file-sharing protocol it describes as about twice as fast as the 9P protocol WSL 2 has used to reach Windows files. Each container session also gets its own virtual hard disk holding its images, containers, networks and volumes, heise reported.

The Compose gap

Most projects that run more than one container describe them in a single Compose file. wslc cannot read one today. Microsoft's roadmap in the post puts wslc compose first, with the goal of running existing compose.yaml files unchanged. heise calls Compose "the most requested feature" and says no date has been given.

Until it arrives, a team moving from Docker Desktop keeps Docker for anything multi-container, or rewrites each service as a separate wslc run command. The second option is a sticking point for a project with a dozen services, because every dependency and startup order has to be restated by hand.

What IT departments get

Microsoft added two Intune settings: "Allow WSL containers access" turns the feature on or off, and "WSL containers registry allow list" limits image pulls to approved registries. The Microsoft Defender for Endpoint plugin now reports process, file and network activity from inside WSL containers.

A new network mode called consomme sends traffic out of the VM as the signed-in user, according to heise, which should help on machines behind a VPN or a strict firewall.

Microsoft did not give a date for wslc compose. The post says only that it is the top priority.

Elsewhere on the developer-tools desk, Nvidia shipped an agent sandbox, covered in Nvidia's OpenShell agent sandbox, and Tcl/Tk 9.1 got its own build notes in Tcl/Tk 9.1.