[BUG]: UseDotNet task installs x86 build on Windows arm64

[azchohfi]

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Task name

UseDotNet

Task version

2

Issue Description

My host is an Arm64 machine, but it trying to install the x86 version of the dotnet sdk.

Environment type (Please select at least one enviroment where you face this issue)

• Self-Hosted
• Microsoft Hosted
• VMSS Pool
• Container

Azure DevOps Server type

dev.azure.com (formerly visualstudio.com)

Azure DevOps Server Version (if applicable)

No response

Operation system

Windows 2022 ARM64

Relevant log output

Tool to install: .NET Core sdk version 8.0.x.
Found version 8.0.400 in channel 8.0 for user specified version spec: 8.0.x
Version 8.0.400 was not found in cache.
Getting URL to download .NET Core sdk version: 8.0.400.
Detecting OS platform to find correct download package for the OS.
C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoLogo -Sta -NoProfile -NonInteractive -ExecutionPolicy Unrestricted -Command "& 'C:\a\_work\_tasks\UseDotNet_b0ce7256-7898-45d3-9cb5-176b752bfea6\2.243.1\externals\get-os-platform.ps1'"
Primary:win-x86
Detected platform (Primary): win-x86
Downloading: https://download.visualstudio.microsoft.com/download/pr/4bc6c939-8cb1-45c4-afde-a1b0715eec7d/c3835988860504c59187049089ca2466/dotnet-sdk-8.0.400-win-x86.zip
Extracting downloaded package C:\a\_work\_temp\1b29a698-0d9b-40f8-837e-492b74a90b1f.
Extracting archive
C:\Windows\system32\chcp.com 65001
Active code page: 65001

C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoLogo -Sta -NoProfile -NonInteractive -ExecutionPolicy Unrestricted -Command "$ErrorActionPreference = 'Stop' ; try { Add-Type -AssemblyName System.IO.Compression.FileSystem } catch { } ; [System.IO.Compression.ZipFile]::ExtractToDirectory('C:\a\_work\_temp\1b29a698-0d9b-40f8-837e-492b74a90b1f', 'C:\a\_work\_temp\99cb')"

Successfully installed .NET Core sdk version 8.0.400.
Creating global tool path and pre-pending to PATH.

Full task logs with system.debug enabled

 [REPLACE THIS WITH YOUR INFORMATION] 

Repro steps

- task: UseDotNet@2
  displayName: Setup .NET 8
  inputs:
    version: 8.0.x

[azchohfi]

This seems to be missing arm64:

azure-pipelines-tasks/Tasks/UseDotNetV2/externals/get-os-platform.ps1

Lines 11 to 12 in a3c064a

	{ ($_ -eq "amd64") -or ($_ -eq "x64") } { return "x64" }
	{ $_ -eq "x86" } { return "x86" }

But weirdly it went the x86 code path.

[aleksandrlevochkin]

Hi @azchohfi thank you for reporting this issue. As I see, the script determines the architecture by checking the env variable PROCESSOR_ARCHITECTURE. It seems like this variable does not necessarily return the actual architecture of the processor but of the process with this env variable.

Is there any chance that you're using the x86 version of the self-hosted agent?

[DHowett]

Is there any chance that you're using the x86 version of the self-hosted agent?

Yes. This is going to be true of all Microsoft-internal 1ES-managed pools, as well.
 

Windows support runs the x86 Azure DevOps agent in emulation mode, so requires a Cobalt or later OS release.
from eng.ms

Fixing this will require the task to be more intelligent than it currently is.

[DHowett]

For example, it is possible to determine the actual architecture using WMI.

$Arch = if ((Get-WmiObject -Class Win32_Processor).Architecture -eq 12) { "arm64" } else { "x64" }

[DHowett]

And final FYI:

dotnet install-scripts has long since been updated to account for this

function Get-Machine-Architecture() {
    Say-Invocation $MyInvocation

    # On PS x86, PROCESSOR_ARCHITECTURE reports x86 even on x64 systems.
    # To get the correct architecture, we need to use PROCESSOR_ARCHITEW6432.
    # PS x64 doesn't define this, so we fall back to PROCESSOR_ARCHITECTURE.
    # Possible values: amd64, x64, x86, arm64, arm
    if( $ENV:PROCESSOR_ARCHITEW6432 -ne $null ) {
        return $ENV:PROCESSOR_ARCHITEW6432
    }

    try {        
        if( ((Get-CimInstance -ClassName CIM_OperatingSystem).OSArchitecture) -like "ARM*") {
            if( [Environment]::Is64BitOperatingSystem )
            {
                return "arm64"
            }  
            return "arm"
        }
    }
    catch {
        # Machine doesn't support Get-CimInstance
    }

    return $ENV:PROCESSOR_ARCHITECTURE
}

function Get-CLIArchitecture-From-Architecture([string]$Architecture) {
    Say-Invocation $MyInvocation

    if ($Architecture -eq "<auto>") {
        $Architecture = Get-Machine-Architecture
    }

    switch ($Architecture.ToLowerInvariant()) {
        { ($_ -eq "amd64") -or ($_ -eq "x64") } { return "x64" }
        { $_ -eq "x86" } { return "x86" }
        { $_ -eq "arm" } { return "arm" }
        { $_ -eq "arm64" } { return "arm64" }
        default { throw "Architecture '$Architecture' not supported. If you think this is a bug, report it at https://github.com/dotnet/install-scripts/issues" }
    }
}

from https://github.com/dotnet/install-scripts/blob/033622cafb10f813db17a4ed511f2bbade9a77ee/src/dotnet-install.ps1#L266

[MichelZ]

@DergachevE you seem to be code owner for this. Any chance this can get reviewed? #20695