Stop forcing MSBuild server for Aspire CLI builds

[Copilot]

Description

aspire run can fail on Linux with .NET SDK 10.0.300 when the CLI forces MSBuild server usage, surfacing as a named-pipe timeout during the AppHost build.

• CLI behavior

  • Stop setting DOTNET_CLI_USE_MSBUILD_SERVER for dotnet run / dotnet build invocations.
  • Let the .NET SDK decide the MSBuild server behavior.

• Tests

  • Update DotNetCliRunner coverage to assert the CLI no longer injects DOTNET_CLI_USE_MSBUILD_SERVER.

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No

[Copilot]

Pull request overview

Removes Aspire CLI’s explicit injection of DOTNET_CLI_USE_MSBUILD_SERVER into dotnet run and AppHost dotnet build process invocations, allowing the .NET SDK/environment to control MSBuild server behavior (avoiding failures seen with .NET SDK 10.0.300 on Linux).

Changes:

• Removed the DOTNET_CLI_USE_MSBUILD_SERVER configuration/injection logic from DotNetCliRunner for RunAsync and BuildAsync.
• Updated DotNetCliRunnerTests to assert that the CLI no longer injects DOTNET_CLI_USE_MSBUILD_SERVER (including when the setting is present in IConfiguration).

Show a summary per file

File	Description
src/Aspire.Cli/DotNet/DotNetCliRunner.cs	Stops injecting DOTNET_CLI_USE_MSBUILD_SERVER for dotnet run and dotnet build executions.
tests/Aspire.Cli.Tests/DotNet/DotNetCliRunnerTests.cs	Updates tests to validate the environment variable is no longer injected.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1

[Copilot]

Fixed in e42a708 by removing the outdated inline comment so the test description matches current behavior.

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 17313

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 17313"

[davidfowl]

/backport to release/13.3

[github-actions]

Started backporting to release/13.3 (link to workflow run)

[aspire-repo-bot]

@davidfowl backporting to release/13.3 failed, the patch most likely resulted in conflicts. Please backport manually!

git am output

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Creating an empty commit: Initial plan
Applying: Stop forcing MSBuild server for CLI dotnet commands
Using index info to reconstruct a base tree...
M	src/Aspire.Cli/DotNet/DotNetCliRunner.cs
M	tests/Aspire.Cli.Tests/DotNet/DotNetCliRunnerTests.cs
Falling back to patching base and 3-way merge...
Auto-merging src/Aspire.Cli/DotNet/DotNetCliRunner.cs
Auto-merging tests/Aspire.Cli.Tests/DotNet/DotNetCliRunnerTests.cs
CONFLICT (content): Merge conflict in tests/Aspire.Cli.Tests/DotNet/DotNetCliRunnerTests.cs
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0002 Stop forcing MSBuild server for CLI dotnet commands
Error: The process '/usr/bin/git' failed with exit code 128

Link to workflow output