Add wslc container cp command for tar archive upload by ptrivedi · Pull Request #40835 · microsoft/WSL

ptrivedi · 2026-06-17T18:08:34Z

Summary

Implements wslc container cp for bidirectional file copy between containers and the local filesystem, plus stdin tar upload into containers, via Docker's archive APIs.

Usage

# Local file to container
wslc container cp ./myfile.txt my_container:/app/

# Container to local
wslc container cp my_container:/etc/ssl/cert.pem C:\temp\certs\

# Pipe a tar archive into a container (stdin)
tar.exe -cf - cert.pem | wslc container cp - my_container:/etc/ssl/

Implementation

Full stack implementation across all layers:

Layer	Change
IDL	Added `UploadArchive` and `DownloadArchive` to `IWSLCContainer`
DockerHTTPClient	Added `PutArchive` and `GetArchive` methods
WSLCContainerImpl	Upload: relay stdin to Docker socket with `SD_SEND` on EOF. Download: stream tar from Docker, extract with tar.exe
ContainerService	Added `CopyToContainer` and `CopyFromContainer` static methods
ContainerTasks	Added `CopyToContainer` task with bidirectional CONTAINER:PATH parsing
ContainerCpCommand	New command registered under `container cp`
Localization	Added all user-facing strings
Tests	CLI parsing test cases + e2e tests for all directions + error cases

Key Design Decisions

Bidirectional copy: Supports local→container, container→local, and stdin→container
Direction detection: Parses CONTAINER:PATH patterns (single letter before colon treated as Windows drive path)
Local file upload: Creates tar via tar.exe, then uploads with known Content-Length
Container download: Downloads tar from Docker, extracts to local directory via tar.exe
Stdin upload: Uses GetFileSizeEx when stdin is a file redirect; omits Content-Length header for pipes (relies on SD_SEND shutdown as EOF signal)
Error handling: Non-200 responses read synchronously with SO_RCVTIMEO timeout to avoid HTTP/1.1 keep-alive hang; JSON parse failures fall back to raw body text
--archive/-a flag: Accepted for Docker CLI compatibility (no-op — Docker always preserves uid/gid from tar headers)
Trailing path separator: Stripped before embedding in tar commands to avoid CRT \" escape bug; root paths preserved with size() > 1 guard

Testing

All WSLCCLI unit tests pass
Added CLI parsing test cases for container cp
Added e2e tests: stdin upload, local file upload, container→local download, trailing backslash regression, nonexistent path/dir/container errors, stopped container copy, invalid direction

Implements 'wslc container cp - CONTAINER:PATH' to copy a tar archive from stdin into a running container via Docker's PUT /containers/{id}/archive API. Usage: tar.exe -cf - files | wslc container cp - my_container:/dest Changes across all layers: - IDL: Added UploadArchive to IWSLCContainer - DockerHTTPClient: Added PutArchive method (omits Content-Length for pipes) - WSLCContainerImpl: Relay stdin to Docker socket with SD_SEND on EOF - ContainerService: Added CopyToContainer static method - ContainerTasks: Added CopyToContainer task with CONTAINER:PATH parsing - ContainerCpCommand: New command registered under 'container cp' - Localization: Added all user-facing strings - Tests: Added CLI parsing test cases and updated e2e command list Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR adds a new wslc container cp subcommand that uploads a tar archive from stdin into a running container by relaying stdin to Docker’s PUT /containers/{id}/archive endpoint, with supporting wiring through the CLI task/service layers and new localized help/error strings.

Changes:

Adds a new container cp command and CLI task/service method to parse CONTAINER:PATH and stream stdin into the container.
Extends the Docker HTTP client with a PutArchive request helper used by the session/container implementation.
Updates tests (CLI parsing + e2e container command list) and adds localized user-facing strings for the new command.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/windows/wslc/e2e/WSLCE2EContainerTests.cpp	Adds `cp` to the container subcommand help list assertions.
test/windows/wslc/CommandLineTestCases.h	Adds command-line parsing coverage for `container cp`.
src/windows/wslcsession/WSLCContainer.h	Declares new UploadArchive APIs on the container implementation and COM wrapper.
src/windows/wslcsession/WSLCContainer.cpp	Implements archive upload by relaying stdin to Docker and handling HTTP responses/errors.
src/windows/wslcsession/DockerHTTPClient.h	Declares `PutArchive` for Docker archive upload.
src/windows/wslcsession/DockerHTTPClient.cpp	Implements `PutArchive` request creation (optionally omitting Content-Length).
src/windows/wslc/tasks/ContainerTasks.h	Declares `CopyToContainer` task entrypoint.
src/windows/wslc/tasks/ContainerTasks.cpp	Implements `CONTAINER:PATH` parsing and stdin validation/size detection.
src/windows/wslc/services/ContainerService.h	Adds `CopyToContainer` service API.
src/windows/wslc/services/ContainerService.cpp	Wires CLI service call to COM `IWSLCContainer::UploadArchive`.
src/windows/wslc/commands/ContainerCpCommand.cpp	Adds the new `container cp` command and argument definitions.
src/windows/wslc/commands/ContainerCommand.h	Declares `ContainerCpCommand`.
src/windows/wslc/commands/ContainerCommand.cpp	Registers `container cp` under the container root command.
src/windows/service/inc/wslc.idl	Adds `UploadArchive` to `IWSLCContainer`.
localization/strings/en-US/Resources.resw	Adds help text and user-facing error messages for `container cp`.

dkbennett

Implementation looks good, but I think this should really have at least 1 E2E test verifying the copy actually works as expected.

Can put it in with one of the other container tests so we dont create an entirely new file for it if necessary, but should have something validating we do not regress this command's functionality in the future and have confidence that it is working correctly.

dkbennett · 2026-06-17T19:45:25Z

Just adding a note that this PR will have a conflict with #40832 due to the change from CreateSession (which is poorly named since it does an open or a create default only) to ResolveSession, depending on which one goes in first. If this one goes in first I can fix it in 40832.

- Add 5 new CLI parsing test cases for cp in CommandLineTestCases.h - Add RunWslcWithStdinFile helper to pipe file contents to wslc stdin - Add WSLCE2EContainerCpTests with 11 e2e test methods covering: - Help output, missing arguments, invalid target formats - Stdin terminal detection, source validation - Container not found error handling - Successful tar upload to running container with exec verification - Copy to stopped container (Docker PUT /archive filesystem operation) - CreateTestTarFile builds minimal POSIX tar at runtime for tests Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Fix ContainerCpDesc to accurately describe stdin-only tar upload (was misleadingly implying bidirectional file copy) - Change PutArchive ContentLength parameter to std::optional<uint64_t> to distinguish 'unknown size' (pipe) from 'known zero size' (empty file) - WSLCContainerImpl::UploadArchive passes std::nullopt when ContentSize is 0 Note: Kept UploadArchive on IWSLCContainer (not a separate IWSLCContainer2) because wslc interfaces are internal — client and server are always deployed together from the same build, so there is no ABI compatibility concern. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

ptrivedi · 2026-06-17T21:39:14Z

Addressed code review feedback:

Description mismatch (fixed): Updated \ContainerCpDesc\ to accurately say 'Copy a tar archive from stdin into a container' instead of implying bidirectional copy.
Content-Length ambiguity (fixed): Changed \PutArchive\ to use \std::optional<uint64_t>\ for ContentLength, properly distinguishing 'unknown size' (pipe, passes \std::nullopt) from 'known zero size' (empty file, passes \

Copilot

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 5 comments.

Copilot

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 4 comments.

- Add Archive argument type in ArgumentDefinitions.h - Add --archive/-a flag to ContainerCpCommand arguments - Add WSLCCLI_ArchiveArgDescription localization string - Add 2 CLI parsing test cases for -a and --archive - Add 2 e2e tests: ArchiveFlag (-a) and ArchiveFlagLongForm (--archive) The flag is accepted for docker cp compatibility. Since the tar stream is relayed directly to Docker's PUT /archive API, uid/gid information from the source tar is always preserved (equivalent to -a behavior). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…rue/false) Add ParseBoolValue() helper to ArgumentParser that accepts true/false/1/0 (case-insensitive). Modify ProcessNamedArgument() and ProcessAliasArgument() to parse adjoined boolean values for flag-type arguments. - --flag=true and -f=true set the flag (equivalent to --flag / -f) - --flag=false and -f=false leave the flag unset - Invalid values produce FlagInvalidBooleanError - Add 8 CLI parsing unit test cases for boolean flag values - Add 5 e2e tests for -a/--archive boolean value variants - All 143 unit tests and 18 e2e tests pass Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 6 comments.

- Validate DestPath is non-empty in UploadArchive (E_INVALIDARG) - Unify CONTAINER:DEST_PATH to CONTAINER:PATH in long description - Guard FromJson with try-catch for non-JSON error responses - Fix RunWslcWithStdinFile declaration line length (>130 col) - Add comment explaining archive flag is intentional no-op for stdin tar Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 4 comments.

+    WSLC_TEST_METHOD(WSLCE2E_Container_Cp_StdinIsTerminal)
+    {
+        // Running without piped stdin should fail with a terminal error.
+        // RunWslcAndRedirectToFile gives the child a real console stdout handle,
+        // and since RunWslc pipes NUL to stdin, we use RunWslcAndRedirectToFile
+        // with no output path to get a real console for the child.
+        const auto result = RunWslcAndRedirectToFile(L"container cp - fakecontainer:/path");
+        VERIFY_IS_TRUE(result.ExitCode.has_value());
+        VERIFY_ARE_EQUAL(1u, result.ExitCode.value());
+        VERIFY_IS_TRUE(result.Stderr.has_value());
+        VERIFY_ARE_NOT_EQUAL(0u, result.Stderr.value().size());
+    }


OneBlue · 2026-06-24T23:51:18Z

+    }
+    else
+    {
+        if (isChunked)


I recommend using DockerHttpResponseHandle, which already handles this

see comment above

OneBlue · 2026-06-24T23:52:12Z

+        {
+            auto error = wsl::shared::FromJson<ErrorResponse>(errorJson.c_str());
+
+            THROW_HR_WITH_USER_ERROR_IF(WSLC_E_CONTAINER_NOT_FOUND, error.message, statusCode == 404);


Same comments as above: 404 shouldn't be possible here, and the below catch block can be removed

Same comments as above: 404 shouldn't be possible here, and the below catch block can be removed

Are you saying because container would already be there? /containers/{}/archive could return 404 when the path is not found. The returned error code definitely needs to be changed from WSLC_E_CONTAINER_NOT_FOUND to WSLC_E_CONTAINER_CP_PATH_NOT_FOUND or something

https://docs.docker.com/reference/api/engine/version/v1.47/#tag/Container/operation/ContainerArchive

("container or path does not exist")

OneBlue · 2026-06-24T23:57:24Z

+        auto tarCmd = std::format(L"tar.exe -cf \"{}\" -C \"{}\" testfile.txt", TarPath.wstring(), tarSrcDir.wstring());
+        STARTUPINFOW si{sizeof(si)};
+        PROCESS_INFORMATION pi{};
+        THROW_LAST_ERROR_IF(!CreateProcessW(nullptr, tarCmd.data(), nullptr, nullptr, FALSE, 0, nullptr, nullptr, &si, &pi));


I recommend using the subprocess helper here as well

Copilot

Pull request overview

Copilot reviewed 21 out of 22 changed files in this pull request and generated 7 comments.

antsok · 2026-06-30T13:37:17Z

It would be great to have this finished. This is needed for Aspire/DCP to run on WSL C.

Copilot

Pull request overview

Copilot reviewed 21 out of 22 changed files in this pull request and generated 7 comments.

The function was accidentally deleted during merge conflict resolution. Restores the original implementation from master which launches 'container logs -f' as a subprocess and uses WaitForOutput to poll until the expected string appears in stdout. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace hardcoded "No file extracted from container archive" with Localization::WSLCCLI_CpNoFileExtractedError() and add the corresponding entry to Resources.resw. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 22 changed files in this pull request and generated 5 comments.

The synchronous recv workaround exists because overlapped ReadFile on hvsockets has delayed EOF detection (~5s stall), not because of HTTP/1.1 keep-alive. Connection: close is already set and the server closes promptly — synchronous recv sees EOF immediately while overlapped ReadFile takes ~5s to signal completion on hvsockets. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 22 changed files in this pull request and generated 9 comments.

+        auto colonPos = path.find(L':');
+        if (colonPos == std::wstring::npos || colonPos == 0)
+        {
+            return false;
+        }


+
+            // Create tar archive — strip trailing separator to avoid the CRT parsing '\"' as an escaped quote
+            auto parentDirStr = parentDir;
+            while (parentDirStr.size() > 1 && (parentDirStr.back() == L'\\' || parentDirStr.back() == L'/'))


+
+            // Strip trailing separator to avoid the CRT parsing a trailing '\"' as an escaped quote
+            auto targetDir = absTarget.wstring();
+            while (targetDir.size() > 1 && (targetDir.back() == L'\\' || targetDir.back() == L'/'))


+            auto cleanupExtract = wil::scope_exit([&] { std::filesystem::remove_all(extractDir); });
+
+            auto extractDirStr = extractDir.wstring();
+            while (extractDirStr.size() > 1 && (extractDirStr.back() == L'\\' || extractDirStr.back() == L'/'))


+            // Ensure parent directory of target exists.
+            std::error_code dirError;
+            std::filesystem::create_directories(absTarget.parent_path(), dirError);
+


+        // Copy local file to container.
+        const auto cpResult = RunWslc(std::format(L"container cp {} {}:/tmp/", localFile.wstring(), WslcContainerName));
+        cpResult.Verify({.Stdout = L"", .Stderr = L"", .ExitCode = 0});


+        // Copy from container to local.
+        const auto cpResult =
+            RunWslc(std::format(L"container cp {}:/tmp/fromcontainer.txt {}", WslcContainerName, downloadDir.wstring()));
+        cpResult.Verify({.Stdout = L"", .Stderr = L"", .ExitCode = 0});


+        // Copy with explicit trailing backslash in target path.
+        auto targetWithBackslash = downloadDir.wstring() + L"\\";
+        const auto cpResult = RunWslc(std::format(L"container cp {}:/tmp/bstest.txt {}", WslcContainerName, targetWithBackslash));
+        cpResult.Verify({.Stdout = L"", .Stderr = L"", .ExitCode = 0});


+        // Copy from container to a specific file path (not a directory).
+        const auto cpResult = RunWslc(std::format(L"container cp {}:/tmp/srcfile.txt {}", WslcContainerName, targetFile.wstring()));
+        cpResult.Verify({.Stdout = L"", .Stderr = L"", .ExitCode = 0});


Check the error code from create_directories when ensuring the parent directory exists for a single-file container-to-local copy, matching the pattern used in the directory-target branch. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 22 changed files in this pull request and generated 5 comments.

+        if (boolVal.value())
+        {
+            AddFlag(firstArg->Type());
+        }
+
+        return {};


+            if (boolVal.value())
+            {
+                AddFlag(nextArg->Type());
+            }
+
+            return {};
+        }


+                    if (boolVal.value())
+                    {
+                        AddFlag(arg.Type());
+                    }
+
+                    return {};


+        // Single letter before colon is a Windows drive path
+        if (colonPos == 1 && std::isalpha(static_cast<unsigned char>(path[0])))
+        {
+            return false;
+        }


+            auto extractDir = std::filesystem::path(tempDir) / L"wslc-cp-extract";
+            std::filesystem::create_directories(extractDir);
+            auto cleanupExtract = wil::scope_exit([&] { std::filesystem::remove_all(extractDir); });


ptrivedi requested a review from a team as a code owner June 17, 2026 18:08

Copilot AI review requested due to automatic review settings June 17, 2026 18:08

Copilot started reviewing on behalf of ptrivedi June 17, 2026 18:09 View session

ptrivedi marked this pull request as draft June 17, 2026 18:09

Copilot AI reviewed Jun 17, 2026

View reviewed changes

Comment thread src/windows/service/inc/wslc.idl

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

Comment thread src/windows/wslcsession/DockerHTTPClient.cpp

dkbennett reviewed Jun 17, 2026

View reviewed changes

Comment thread src/windows/wslc/commands/ContainerCommand.cpp

Pooja Trivedi and others added 2 commits June 17, 2026 16:33

Copilot AI review requested due to automatic review settings June 17, 2026 21:35

Copilot started reviewing on behalf of ptrivedi June 17, 2026 21:36 View session

Remove accidentally committed test VHD files

b148cca

Copilot AI reviewed Jun 17, 2026

View reviewed changes

Comment thread src/windows/service/inc/wslc.idl

Comment thread src/windows/wslcsession/WSLCContainer.cpp

Comment thread test/windows/wslc/e2e/WSLCExecutor.h

Comment thread src/windows/wslcsession/WSLCContainer.cpp

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

Fix clang format errors

ff5aeb4

Copilot AI review requested due to automatic review settings June 17, 2026 22:19

Copilot started reviewing on behalf of ptrivedi June 17, 2026 22:20 View session

Copilot AI reviewed Jun 17, 2026

View reviewed changes

Comment thread src/windows/service/inc/wslc.idl

Comment thread src/windows/wslcsession/WSLCContainer.cpp

Comment thread test/windows/wslc/e2e/WSLCE2EContainerCpTests.cpp

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

Pooja Trivedi and others added 2 commits June 17, 2026 19:43

Copilot AI review requested due to automatic review settings June 18, 2026 01:09

Copilot started reviewing on behalf of ptrivedi June 18, 2026 01:09 View session

Copilot AI reviewed Jun 18, 2026

View reviewed changes

Pooja Trivedi and others added 2 commits June 17, 2026 21:40

Fix clang format errors

cdea6af

Copilot AI review requested due to automatic review settings June 18, 2026 01:49

Copilot started reviewing on behalf of ptrivedi June 18, 2026 01:51 View session

Copilot AI reviewed Jun 18, 2026

View reviewed changes

ptrivedi marked this pull request as ready for review June 18, 2026 19:14

OneBlue requested changes Jun 24, 2026

View reviewed changes

clang format fixes

739ec44

Copilot AI review requested due to automatic review settings June 25, 2026 00:01

Copilot started reviewing on behalf of ptrivedi June 25, 2026 00:02 View session

Copilot AI reviewed Jun 25, 2026

View reviewed changes

antsok mentioned this pull request Jun 30, 2026

Add support for WSL Containers runtime microsoft/dcp#194

Open

ptrivedi added 2 commits July 1, 2026 12:11

Merge branch 'master' into feature/wslc-container-cp

e6d7db8

Merge branch 'master' into feature/wslc-container-cp

d2d77a0

Copilot AI review requested due to automatic review settings July 2, 2026 14:41

Copilot started reviewing on behalf of ptrivedi July 2, 2026 14:41 View session

Copilot AI reviewed Jul 2, 2026

View reviewed changes

Pooja Trivedi and others added 4 commits July 2, 2026 11:01

fix clang format errors

3be12b6

Addressed code review comments

1ccef43

Localize hardcoded error string in container cp

4f3868a

Replace hardcoded "No file extracted from container archive" with Localization::WSLCCLI_CpNoFileExtractedError() and add the corresponding entry to Resources.resw. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings July 2, 2026 15:58

Copilot started reviewing on behalf of ptrivedi July 2, 2026 15:58 View session

Copilot AI reviewed Jul 2, 2026

View reviewed changes

Comment thread src/windows/wslc/arguments/ArgumentParser.cpp

Comment thread src/windows/wslc/arguments/ArgumentParser.cpp

Comment thread src/windows/wslc/arguments/ArgumentParser.cpp

Comment thread src/windows/wslc/tasks/ContainerTasks.cpp

Comment thread src/windows/wslc/tasks/ContainerTasks.cpp

Pooja Trivedi and others added 2 commits July 2, 2026 15:23

Fix end to end test error message

31cfe5d

Copilot AI review requested due to automatic review settings July 2, 2026 20:00

Copilot started reviewing on behalf of ptrivedi July 2, 2026 20:00 View session

Copilot AI reviewed Jul 2, 2026

View reviewed changes

ptrivedi and others added 2 commits July 2, 2026 16:47

Merge branch 'master' into feature/wslc-container-cp

8eec9df

Copilot AI review requested due to automatic review settings July 2, 2026 21:02

Copilot started reviewing on behalf of ptrivedi July 2, 2026 21:02 View session

Copilot AI reviewed Jul 2, 2026

View reviewed changes

Merge branch 'master' into feature/wslc-container-cp

6e0a512

Uh oh!

Conversation

ptrivedi commented Jun 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Usage

Implementation

Key Design Decisions

Testing

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

dkbennett left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

dkbennett commented Jun 17, 2026

Uh oh!

ptrivedi commented Jun 17, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

OneBlue Jun 24, 2026

Choose a reason for hiding this comment

Uh oh!

ptrivedi Jul 2, 2026

Choose a reason for hiding this comment

Uh oh!

OneBlue Jun 24, 2026

Choose a reason for hiding this comment

Uh oh!

ptrivedi Jul 1, 2026

Choose a reason for hiding this comment

Uh oh!

ptrivedi Jul 1, 2026

Choose a reason for hiding this comment

Uh oh!

ptrivedi commented Jun 17, 2026 •

edited

Loading