CLI: Initial support for DNS options by AmelBawa-msft · Pull Request #40138 · microsoft/WSL

AmelBawa-msft · 2026-04-08T23:27:04Z

Summary of the Pull Request

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

Validation Steps Performed

Copilot

Pull request overview

This PR exposes Docker-style DNS configuration flags on wslc container run/create, plumbs the parsed values into container creation, and adds E2E coverage + a localized validation error for --no-dns conflicts.

Changes:

Add --dns, --dns-search, --dns-option, --dns-domain, and --no-dns to container run/create argument sets and parsing.
Forward DNS settings into container creation via ContainerOptions → WSLCContainerLauncher.
Add E2E tests for DNS flags and a localized error message for --no-dns flag conflicts.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/windows/wslc/e2e/WSLCE2EContainerRunTests.cpp	Adds E2E tests and help-text expectations for DNS flags on `container run`.
test/windows/wslc/e2e/WSLCE2EContainerCreateTests.cpp	Adds E2E tests and help-text expectations for DNS flags on `container create`.
src/windows/wslc/tasks/ContainerTasks.cpp	Parses new DNS-related CLI args into `ContainerOptions`.
src/windows/wslc/services/ContainerService.cpp	Forwards DNS-related `ContainerOptions` into `WSLCContainerLauncher` before container creation.
src/windows/wslc/services/ContainerModel.h	Extends `ContainerOptions` with DNS-related fields (servers/search/options/domain + `NoDns`).
src/windows/wslc/commands/ContainerRunCommand.cpp	Exposes DNS-related arguments for `container run` (including multi-use args).
src/windows/wslc/commands/ContainerCreateCommand.cpp	Exposes DNS-related arguments for `container create` (including multi-use args).
src/windows/wslc/arguments/ArgumentValidation.cpp	Adds validation preventing `--no-dns` from being used with DNS configuration flags.
src/windows/wslc/arguments/ArgumentDefinitions.h	Un-comments/adds definitions for DNS args and `--no-dns`.
localization/strings/en-US/Resources.resw	Adds localized `--no-dns` conflict error string.

Copilot · 2026-04-08T23:34:17Z

src/windows/wslc/tasks/ContainerTasks.cpp

+
+    if (context.Args.Contains(ArgType::NoDNS))
+    {
+        options.NoDns = true;


--no-dns is parsed into ContainerOptions::NoDns here, but that flag is never consumed when creating/running the container (no references to options.NoDns elsewhere). As a result, --no-dns currently has no behavioral effect beyond conflict validation. Either plumb this through to the container create request (e.g., an explicit runtime/HostConfig setting) or remove the flag until it’s supported.

Suggested change

options.NoDns = true;

THROW_HR_MSG(E_NOTIMPL, "--no-dns is not currently supported.");

Copilot · 2026-04-08T23:34:17Z

src/windows/wslc/services/ContainerService.cpp

+    if (!options.DnsDomain.empty())
+    {
+        auto domainname = options.DnsDomain;
+        containerLauncher.SetDomainname(std::move(domainname));
+    }
+
+    if (!options.DnsOptions.empty())
+    {
+        auto dnsOptions = options.DnsOptions;
+        containerLauncher.SetDnsOptions(std::move(dnsOptions));
+    }
+
+    if (!options.DnsSearchDomains.empty())
+    {
+        auto dnsSearchDomains = options.DnsSearchDomains;


--dns-domain is wired to WSLCContainerLauncher::SetDomainname() (Docker Domainname field), which sets the container domainname/hostname domain rather than resolv.conf DNS search/default-domain configuration. This appears inconsistent with the option name/description (“default DNS Domain”). Consider renaming the option to match Docker (--domainname) or changing the implementation to affect DNS resolution (e.g., via DnsSearchDomains/resolv.conf semantics) so behavior matches the CLI surface.

Suggested change

if (!options.DnsDomain.empty())

{

auto domainname = options.DnsDomain;

containerLauncher.SetDomainname(std::move(domainname));

}

if (!options.DnsOptions.empty())

{

auto dnsOptions = options.DnsOptions;

containerLauncher.SetDnsOptions(std::move(dnsOptions));

}

if (!options.DnsSearchDomains.empty())

{

auto dnsSearchDomains = options.DnsSearchDomains;

if (!options.DnsOptions.empty())

{

auto dnsOptions = options.DnsOptions;

containerLauncher.SetDnsOptions(std::move(dnsOptions));

}

auto dnsSearchDomains = options.DnsSearchDomains;

if (!options.DnsDomain.empty())

{

dnsSearchDomains.emplace_back(options.DnsDomain);

}

if (!dnsSearchDomains.empty())

{

Copilot · 2026-04-08T23:34:17Z

test/windows/wslc/e2e/WSLCE2EContainerRunTests.cpp

+    TEST_METHOD(WSLCE2E_Container_Run_DNS_Search)
+    {
+        WSL2_TEST_ONLY();
+
+        auto result = RunWslc(std::format(
+            L"container run --rm --dns-search example.com {} cat /etc/resolv.conf", DebianImage.NameAndTag()));
+        result.Verify({.ExitCode = 0});
+        VERIFY_IS_TRUE(result.Stdout->find(L"search example.com") != std::wstring::npos);
+    }
+
+    TEST_METHOD(WSLCE2E_Container_Run_DNS_Option)
+    {
+        WSL2_TEST_ONLY();
+
+        auto result = RunWslc(std::format(
+            L"container run --rm --dns-option ndots:5 {} cat /etc/resolv.conf", DebianImage.NameAndTag()));
+        result.Verify({.ExitCode = 0});
+        VERIFY_IS_TRUE(result.Stdout->find(L"options ndots:5") != std::wstring::npos);
+    }
+
+    TEST_METHOD(WSLCE2E_Container_Run_DNS_AllOptions)
+    {
+        WSL2_TEST_ONLY();
+
+        auto result = RunWslc(std::format(
+            L"container run --rm --dns 1.1.1.1 --dns-search test.local --dns-option ndots:3 {} cat /etc/resolv.conf",
+            DebianImage.NameAndTag()));
+        result.Verify({.ExitCode = 0});
+        VERIFY_IS_TRUE(result.Stdout->find(L"nameserver 1.1.1.1") != std::wstring::npos);
+        VERIFY_IS_TRUE(result.Stdout->find(L"search test.local") != std::wstring::npos);
+        VERIFY_IS_TRUE(result.Stdout->find(L"options ndots:3") != std::wstring::npos);
+    }


The new DNS test coverage exercises --dns, --dns-search, and --dns-option, but there’s no E2E test validating the behavior of the newly exposed --dns-domain option (only its presence in help/conflict text). Adding a test that asserts the expected in-container effect would prevent regressions and clarify intended semantics.

Copilot · 2026-04-08T23:34:18Z

test/windows/wslc/e2e/WSLCE2EContainerCreateTests.cpp

+    TEST_METHOD(WSLCE2E_Container_Create_NoDNS_ConflictWithDNS_Fails)
+    {
+        WSL2_TEST_ONLY();
+
+        auto result = RunWslc(std::format(
+            L"container create --name {} --no-dns --dns 8.8.8.8 {} echo test",
+            WslcContainerName, DebianImage.NameAndTag()));
+        result.Verify({.Stderr = L"Cannot use --no-dns with --dns, --dns-domain, --dns-option, or --dns-search\r\n", .ExitCode = 1});
+    }


The new tests validate the --no-dns conflict error, but there’s no test that --no-dns alone actually changes container behavior (and the flag currently isn’t applied during container creation). Once --no-dns is implemented, add an E2E assertion for the expected resolv.conf/DNS behavior when it’s set.

Copilot AI review requested due to automatic review settings April 8, 2026 23:27

AmelBawa-msft changed the title ~~Added DNS options~~ CLI: Initial support for DNS options Apr 8, 2026

Copilot started reviewing on behalf of AmelBawa-msft April 8, 2026 23:27 View session

Copilot AI reviewed Apr 8, 2026

View reviewed changes

Added dns options

d26d2d3

benhillis force-pushed the user/amelbawa/dns branch from b8b740b to d26d2d3 Compare April 9, 2026 18:50

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CLI: Initial support for DNS options#40138

CLI: Initial support for DNS options#40138
AmelBawa-msft wants to merge 1 commit intofeature/wsl-for-appsfrom
user/amelbawa/dns

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	options.NoDns = true;
	THROW_HR_MSG(E_NOTIMPL, "--no-dns is not currently supported.");

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AmelBawa-msft commented Apr 8, 2026

Summary of the Pull Request

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