Add support for wslc container restart command by beena352 · Pull Request #41005 · microsoft/WSL

beena352 · 2026-07-06T18:14:19Z

Summary of the Pull Request

Adds wslc container restart which stops and then starts a container, matching Docker CLI semantics. Supports --signal and --time options (defaults: SIGTERM, 5s timeout).

PR Checklist

Closes: Link to issue #xxx
Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
Tests: Added/updated if needed and all pass
Localization: All end user facing strings can be localized
Dev docs: Added/updated if needed
Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Behavior:

Running container: sends signal, waits for timeout, then starts.
Stopped/Exited container: skips stop phase, starts directly.
Created (never-started) container: starts directly.
--rm container: refused with ERROR_INVALID_STATE — Stop would trigger auto-delete via OnStopped, destroying the container.
Not-found container: returns WSLC_E_CONTAINER_NOT_FOUND.

Implementation path: ContainerRestartCommand → ContainerTasks::RestartContainers → ContainerService::Restart → IWSLCContainer::Restart → WSLCContainerImpl::Restart.

N.B. Lock design: WSLCContainerImpl::Restart snapshots state/flags under a shared lock, then releases before calling Stop and Start (which each take the lock exclusively). This is intentional - m_lock is a non-recursive wil::srwlock. If the container self-exits between the snapshot and Stop, Stop no-ops on the Exited state.

Follow-up: To achieve full Docker parity for --rm containers (Docker allows restart on --rm by suppressing auto-remove during the restart window), a follow-up PR will add a member flag m_restartInProgress guarded by wil::scope_exit and checked in OnStopped. This closes the race where a natural container exit between Stop and Start would trigger auto-delete. Shipping the --rm guard (refuse) now is the safe default; the member-flag approach needs its own review and dedicated tests for the self-exit race.

Validation Steps Performed

Unit tests (test/windows/WSLCTests.cpp — ContainerRestart):

Restart running container → stops then starts, state returns to Running
Restart exited container → starts, state returns to Running
Restart created container → starts, state returns to Running
Restart --rm container → refused with ERROR_INVALID_STATE and exact localized message
Restart on already-deleted COM object → fails with RPC_E_DISCONNECTED (object disconnected after delete)

E2E tests (test/windows/wslc/e2e/WSLCE2EContainerRestartTests.cpp):

--help output
Restart running container (by ID)
Restart stopped container
Restart by name
Container not found
Only targeted container restarted (multi-container)
--rm container refused with exact error + HRESULT
Invalid signal (0, 32)
Invalid timeout (non-numeric)

Manual validation:

wslc container run -d --name test debian:latest sleep infinity
wslc container restart test -t 0
wslc container ls # confirms running
wslc container stop test -t 0
wslc container restart test -t 0
wslc container ls # confirms running again

Copilot

Pull request overview

This PR adds a new wslc container restart subcommand that mirrors Docker CLI semantics by stopping (with configurable --signal/--time) and then starting a container, with end-to-end wiring from CLI → service layer → COM interface → session implementation, plus unit/E2E coverage and localized strings.

Changes:

Add a new CLI command wslc container restart and route it through ContainerTasks and ContainerService.
Extend the internal IWSLCContainer COM interface with Restart(...) and implement restart logic in WSLCContainerImpl.
Add unit and E2E tests, update container subcommand help expectations, and add localization strings for help + user-facing errors.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/windows/WSLCTests.cpp	Adds unit tests for container restart behaviors and error cases.
test/windows/wslc/e2e/WSLCE2EContainerTests.cpp	Updates container command help to include the new `restart` subcommand.
test/windows/wslc/e2e/WSLCE2EContainerRestartTests.cpp	New E2E tests validating `container restart` CLI behavior and help output.
src/windows/wslcsession/WSLCContainer.h	Adds restart APIs on `WSLCContainerImpl` and COM `WSLCContainer`.
src/windows/wslcsession/WSLCContainer.cpp	Implements restart logic and exposes it via COM with warning callback context.
src/windows/wslc/tasks/ContainerTasks.h	Declares `RestartContainers` task.
src/windows/wslc/tasks/ContainerTasks.cpp	Implements CLI task parsing/loop for restarting one or more containers.
src/windows/wslc/services/ContainerService.h	Adds `ContainerService::Restart` declaration.
src/windows/wslc/services/ContainerService.cpp	Implements `Restart` by opening the container and calling COM `Restart`.
src/windows/wslc/commands/ContainerRestartCommand.cpp	New command implementation for argument wiring + execution pipeline.
src/windows/wslc/commands/ContainerCommand.h	Declares the `ContainerRestartCommand` type.
src/windows/wslc/commands/ContainerCommand.cpp	Registers `restart` as a container subcommand.
src/windows/service/inc/wslc.idl	Extends `IWSLCContainer` with the `Restart` method.
localization/strings/en-US/Resources.resw	Adds localized strings for restart command descriptions and `--rm` refusal message.

Copilot

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

Copilot

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

beena352 · 2026-07-06T18:57:14Z

+std::vector<Argument> ContainerRestartCommand::GetArguments() const
+{
+    return {
+        Argument::Create(ArgType::ContainerId, std::nullopt, NO_LIMIT),


Intentionally matches ContainerStopCommand's pattern, restart is the lifecycle sibling of stop (same -s/-t flags, same semantics). If we change restart to require the arg, we should also change stop for consistency, which is a separate discussion.

Agree we should change those too, this one should probably have required arg true for container-id. I can put out a quick PR to change those to required so they are consistent with Docker.

PR for fixing stop: #41108

So you can change this one too.

OneBlue

Unfortunately I'm not sure that Restart() can be easily implemented with our existing locking story.

We have a work item to rethink the container state machine & locking logic to allow concurrent Stop() & Kill() calls, I think we're unfortunately going to have for that change before we can implement restart

OneBlue · 2026-07-06T20:50:24Z

+    }
+
+    // Refuse --rm before stopping: Stop -> OnStopped would delete the container.
+    THROW_HR_WITH_USER_ERROR_IF(


I don't think this is the behavior we want: Docker supports restarting containers when --rm is set.

OneBlue · 2026-07-06T20:51:36Z

+        snapshotFlags = m_containerFlags;
+    }
+
+    // Refuse --rm before stopping: Stop -> OnStopped would delete the container.


Locking wise, I don't think that we can drop the lock here unfortunately, otherwise another stop / start operation could arrive before we complete, which would leak to weird states

beena352 · 2026-07-06T22:08:19Z

Unfortunately I'm not sure that Restart() can be easily implemented with our existing locking story.

We have a work item to rethink the container state machine & locking logic to allow concurrent Stop() & Kill() calls, I think we're unfortunately going to have for that change before we can implement restart

Marking this PR as Draft and blocked by Deliverable 62987921 (“[WSL] [Containers] Rethink the WSLCContainer state machine”).
I’ll resume/rework restart once that state-machine/locking change lands, including Docker-parity --rm behavior.

dkbennett

Command implementation looks good, some minor things. Main thing to draw to attention is the change in how help is validated across the CLI from the recent help change. All other commands have been updated for it, so this one could just mimic what other container commands are now doing with regards to help tests.

dkbennett · 2026-07-17T18:50:13Z

+    const std::wstring WslcContainerName2 = L"wslc-test-container-2";
+    const TestImage& DebianImage = DebianTestImage();
+
+    std::wstring GetHelpMessage() const


All of the help test validation has changed since this PR was created. It was changed for the better - you don't need to have precise help output validation anymore, so some bits can be cut from this PR.

dkbennett · 2026-07-17T18:52:39Z

    THROW_IF_FAILED_EXCEPT(container->Stop(options.Signal, options.Timeout), WSLC_E_CONTAINER_NOT_RUNNING);
 }

+void ContainerService::Restart(Session& session, const std::string& id, StopContainerOptions options)


minor nit: The ContainerService seems to have lost its alphabetical function ordering, would recommend moving the function (and header) to be as best in alphabetical as you can make it, at least as close as you can make it to other stuff, like before a cluster of S's or what similar.

dkbennett · 2026-07-17T18:54:45Z

+    return Localization::WSLCCLI_ContainerRestartLongDesc();
+}
+
+// clang-format off


nit: we try to avoid the clang-format off now. Other commands will put empty comments as line breaks in the context chain in ExecuteInternal instead.

See: ContainerStatsCommand.cpp as an example.

We just do this for readability of the chain and this is a nice compromise for having that readability while keeping the clang formatter enabled.

dkbennett · 2026-07-17T18:56:48Z

+std::vector<Argument> ContainerRestartCommand::GetArguments() const
+{
+    return {
+        Argument::Create(ArgType::ContainerId, std::nullopt, NO_LIMIT),


Agree we should change those too, this one should probably have required arg true for container-id. I can put out a quick PR to change those to required so they are consistent with Docker.

Add support for wslc container restart command

3bc0fd7

Copilot AI review requested due to automatic review settings July 6, 2026 18:14

Copilot started reviewing on behalf of beena352 July 6, 2026 18:14 View session

Copilot AI reviewed Jul 6, 2026

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Comment thread localization/strings/en-US/Resources.resw Outdated

Comment thread test/windows/WSLCTests.cpp

Format

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beena352 requested a review from Copilot July 6, 2026 18:38

Copilot started reviewing on behalf of beena352 July 6, 2026 18:39 View session

Copilot AI reviewed Jul 6, 2026

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beena352 requested a review from Copilot July 6, 2026 18:45

Copilot started reviewing on behalf of beena352 July 6, 2026 18:46 View session

Copilot AI reviewed Jul 6, 2026

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beena352 marked this pull request as ready for review July 6, 2026 18:57

beena352 requested a review from a team as a code owner July 6, 2026 18:57

OneBlue reviewed Jul 6, 2026

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beena352 marked this pull request as draft July 6, 2026 22:08

dkbennett reviewed Jul 17, 2026

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Summary of the Pull Request

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beena352 commented Jul 6, 2026 •

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