Move Ubuntu Helix queues to bare 24.04/26.04 VMs

[richlander]

Now that Ubuntu 26.04 VMs (and 24.04 VMs) are available in Helix, move the Ubuntu Helix coverage off the temporary containers-on-Azure-Linux arrangement and back onto bare Ubuntu VMs, per the Ubuntu 26.04 VM Plan (#125748). This restores the bare-VM testing the policy calls for and retires the 22.04 VMs by moving the oldest slots to 24.04.

Changes

eng/pipelines/helix-platforms.yml

Slot	Before	After
helix_linux_x64_oldest (+_internal)	Ubuntu 22.04 container on AzureLinux	bare Ubuntu.2404.Amd64.Open / Ubuntu.2404.Amd64
helix_linux_x64_ubuntu_latest	Ubuntu 26.04 container on AzureLinux	bare Ubuntu.2604.Amd64.Open
helix_linux_x64_ubuntu_oldest	Ubuntu 22.04 container on AzureLinux	bare Ubuntu.2404.Amd64.Open
helix_linux_arm64_latest	Ubuntu 26.04 container on AzureLinux	bare Ubuntu.2604.ArmArch.Open
helix_linux_arm64_oldest	Ubuntu 22.04 container on AzureLinux	bare Ubuntu.2404.ArmArch.Open
helix_browser_wasm_oldest	ubuntu-22.04-helix-webassembly-amd64	ubuntu-24.04-helix-webassembly-amd64

eng/pipelines/libraries/helix-queues-setup.yml

• CoreCLR primary distro (general set) → bare Ubuntu.2604.Amd64.Open

.github/skills/update-os-coverage/SKILL.md

• Use the MCR registry tag list as the source of truth for verifying container image tags; note that the dotnet/versions image-info JSON is in flux pending the ORAS/OCI-artifact migration (dotnet/docker-tools#2142).

Notes

• WASM stays containerized (latest 26.04, oldest 24.04) because the WebAssembly toolchain image is required; only the image version moves.
• All bare-VM queues and image tags were verified present (Helix queue API and MCR registry tag list).
• Residual 22.04 usage is intentionally not in this PR and remains tracked in Tracking: Ubuntu 26.04 VM Plan #125748:
  • Android emulator VMs (Ubuntu.2204.Amd64.Android.*) — no 24.04/26.04 Android Helix queue exists yet (needs dnceng).
  • SuperPMI ARM/arm64 host VMs (Ubuntu.2204.ArmArch) in src/coreclr/scripts/superpmi_collect_setup.py.

Reference: OS onboarding guide

Note

This pull request was AI/Copilot-generated.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/runtime-infrastructure
See info in area-owners.md if you want to be subscribed.

[Copilot]

Pull request overview

This PR updates Helix queue selection to shift Ubuntu coverage from the temporary “containers-on-AzureLinux” setup back to bare Ubuntu VM queues, using Ubuntu 24.04 for “oldest” coverage and Ubuntu 26.04 for “latest” where applicable.

Changes:

• Switch the libraries “CoreCLR primary distro” queue to bare Ubuntu.2604.Amd64.Open.
• Update helix-platforms.yml Ubuntu x64/arm64 “oldest/latest” variables to bare 24.04/26.04 VM queues (while keeping WASM containerized and bumping its oldest image to 24.04).
• Update the OS coverage skill guidance to verify prereqs image tags via the MCR registry tag list (treating the dotnet/versions image-info JSON as a secondary cross-check).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
eng/pipelines/libraries/helix-queues-setup.yml	Moves the primary Linux x64 CoreCLR libraries queue to bare Ubuntu.2604.Amd64.Open.
eng/pipelines/helix-platforms.yml	Re-points Ubuntu oldest/latest variables to bare 24.04/26.04 VM queues; updates WASM oldest container tag to 24.04.
.github/skills/update-os-coverage/SKILL.md	Updates documentation to validate prereqs container tags via the MCR registry tag list and explains why image-info may be stale.

[richlander]

This PR effectively reverts (by design) this prior change: #125535

[github-actions]

Copilot Code Review

Holistic Assessment

Motivation: Justified — restores the repo's intended bare-VM testing policy for Ubuntu now that 24.04 and 26.04 Helix VMs are available, removing the temporary container-on-AzureLinux workaround. Tracked in #125748.

Approach: Correct — straightforward slot-by-slot replacement from container references to bare VM queue names, with WASM intentionally kept on containers (toolchain image required). Documentation updates to the update-os-coverage SKILL.md are a reasonable scope addition given the image-info publishing flux.

Summary: ✅ LGTM. The changes are syntactically consistent with existing patterns, well-scoped, and clearly documented. Queue names follow established conventions (Ubuntu.XXYY.{Amd64|ArmArch}.Open for public, without .Open for internal). Residual 22.04 usage (Android, SuperPMI) is explicitly called out as tracked separately.

---

Detailed Findings

Detailed Findings

✅ Queue name consistency — Bare VM format matches codebase conventions

All new bare VM values (Ubuntu.2404.Amd64.Open, Ubuntu.2404.Amd64, Ubuntu.2604.Amd64.Open, Ubuntu.2404.ArmArch.Open, Ubuntu.2604.ArmArch.Open) follow the exact naming patterns used elsewhere in helix-platforms.yml (e.g., AzureLinux.3.Amd64.Open, OSX.26.Arm64.Open). Internal variants correctly drop the .Open suffix.

✅ WASM container correctly stays containerized — Version bump from 22.04 → 24.04 is appropriate

helix_browser_wasm_oldest retains the (QueueAlias)HostQueue@container format, correctly recognizing that WASM testing requires the WebAssembly toolchain image. The container tag ubuntu-24.04-helix-webassembly-amd64 is stated as verified.

✅ helix-queues-setup.yml — CoreCLR primary distro change is consistent

The CoreCLR primary distro moves from a container+digest reference to bare Ubuntu.2604.Amd64.Open, matching the helix_linux_x64_ubuntu_latest variable in helix-platforms.yml. The Mono path intentionally retains its container reference per commit 280ff3d ("Keep Mono path on Ubuntu 26.04 container").

✅ SKILL.md documentation — Reasonable pragmatic update

Shifting verification guidance from image-info JSON to the MCR registry tag list is appropriate given the documented publishing instability (dotnet/docker-tools#2142). The warning callout clearly marks this as transitional and instructs revisiting once the ORAS-based solution ships.

💡 Minor observation — sha256 digest loss in helix-queues-setup.yml

The previous CoreCLR primary distro had a @sha256:... digest pin. Since this is now a bare VM (no container image), the pin is N/A. No action needed, but noting for awareness that other distro entries in the same block retain digest pins for their containers.

Note

This review was created by GitHub Copilot.

Generated by Code Review for issue #129863 · ● 18.3M · ◷

[richlander]

@wfurt -- Is libmsquic incompatible with Ubuntu 26.04 and/or Linux kernel 7.0?

Console log: 'System.Net.Quic.Functional.Tests' from job 1586e2c2-fd3b-4571-9b14-ad567985de6f workitem b214d261-e8c3-456d-9476-6ba02762f704 (ubuntu.2604.amd64.open.rt) executed on machine a000001 running Linux-7.0.0-1004-azure-x86_64-with-glibc2.43
+ export __TestArchitecture=x64
+ ./RunTests.sh --runtime-path /datadisks/disk1/work/A87F0957/p
========================= Begin custom configuration settings ==============================
export __IsXUnitLogCheckerSupported=1
export XUNIT_HIDE_PASSING_OUTPUT_DIAGNOSTICS=1
========================== End custom configuration settings ===============================
----- start Thu Jun 25 09:58:27 PM UTC 2026 =============== To repro directly: =====================================================
pushd .
/datadisks/disk1/work/A87F0957/p/dotnet exec --runtimeconfig System.Net.Quic.Functional.Tests.runtimeconfig.json --depsfile System.Net.Quic.Functional.Tests.deps.json xunit.console.dll System.Net.Quic.Functional.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing 
popd
===========================================================================================================
/datadisks/disk1/work/A87F0957/w/A39E08B6/e /datadisks/disk1/work/A87F0957/w/A39E08B6/e
  Discovering: System.Net.Quic.Functional.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Net.Quic.Functional.Tests (found 5 of 158 test cases)
  Starting:    System.Net.Quic.Functional.Tests (parallel test collections = on [2 threads], stop on fail = off)
MsQuic not supported and using 'unknown' .
    System.Net.Quic.Tests.MsQuicPlatformDetectionTests.SupportedLinuxPlatforms_IsSupportedIsTrue [FAIL]
      Assert.True() Failure
      Expected: True
      Actual:   False
      Stack Trace:
        /_/src/libraries/System.Net.Quic/tests/FunctionalTests/MsQuicPlatformDetectionTests.cs(66,0): at System.Net.Quic.Tests.MsQuicPlatformDetectionTests.SupportedLinuxPlatforms_IsSupportedIsTrue()
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs(1188,0): at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(37,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(57,0): at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
      Output:
        Running on Distro=ubuntu VersionId=24.4
  Finished:    System.Net.Quic.Functional.Tests