Backport dotnet-watch changes to main/.NET 11#10960
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jonathanpeppers wants to merge 5 commits intomainfrom
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Backport dotnet-watch changes to main/.NET 11#10960jonathanpeppers wants to merge 5 commits intomainfrom
dotnet-watch changes to main/.NET 11#10960jonathanpeppers wants to merge 5 commits intomainfrom
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Context: dotnet/sdk@bd5d3af `dotnet run` now passes in `dotnet run -e FOO=BAR` as `@(RuntimeEnvironmentVariable)` MSBuild items. To opt in to this new feature, we need to add: <ProjectCapability Include="RuntimeEnvironmentVariableSupport" /> As well as update the `_GenerateEnvironmentFiles` MSBuild target: <!-- RuntimeEnvironmentVariable items come from 'dotnet run -e NAME=VALUE' --> <_GeneratedAndroidEnvironment Include="@(RuntimeEnvironmentVariable->'%(Identity)=%(Value)')" /> I added a new test to verify we have the env vars on-device at runtime. Note that I tested this in combination with a local .NET SDK build: * #10769 We won't be able to merge this until we have a .NET SDK here that includes the above commit. Merging with nightly .NET 10.0.3xx SDK.
Context: dotnet/sdk#52492 Context: dotnet/sdk#52581 `dotnet-watch` now runs Android applications via: dotnet watch 🚀 [helloandroid (net10.0-android)] Launched 'D:\src\xamarin-android\bin\Debug\dotnet\dotnet.exe' with arguments 'run --no-build -e DOTNET_WATCH=1 -e DOTNET_WATCH_ITERATION=1 -e DOTNET_MODIFIABLE_ASSEMBLIES=debug -e DOTNET_WATCH_HOTRELOAD_WEBSOCKET_ENDPOINT=ws://localhost:9000 -e DOTNET_STARTUP_HOOKS=D:\src\xamarin-android\bin\Debug\dotnet\sdk\10.0.300-dev\DotnetTools\dotnet-watch\10.0.300-dev\tools\net10.0\any\hotreload\net10.0\Microsoft.Extensions.DotNetDeltaApplier.dll -bl': process id 3356 And so the pieces on Android for this to work are: ~~ Startup Hook Assembly ~~ Parse out the value: <_AndroidHotReloadAgentAssemblyPath>@(RuntimeEnvironmentVariable->WithMetadataValue('Identity', 'DOTNET_STARTUP_HOOKS')->'%(Value)'->Exists())</_AndroidHotReloadAgentAssemblyPath> And verify this assembly is included in the app: <ResolvedFileToPublish Include="$(_AndroidHotReloadAgentAssemblyPath)" /> Then, for Android, we need to patch up `$DOTNET_STARTUP_HOOKS` to be just the assembly name, not the full path: <_AndroidHotReloadAgentAssemblyName>$([System.IO.Path]::GetFileNameWithoutExtension('$(_AndroidHotReloadAgentAssemblyPath)'))</_AndroidHotReloadAgentAssemblyName> ... <RuntimeEnvironmentVariable Include="DOTNET_STARTUP_HOOKS" Value="$(_AndroidHotReloadAgentAssemblyName)" /> ~~ Port Forwarding ~~ A new `_AndroidConfigureAdbReverse` target runs after deploying apps, that does: adb reverse tcp:9000 tcp:9000 I parsed the value out of: <_AndroidWebSocketEndpoint>@(RuntimeEnvironmentVariable->WithMetadataValue('Identity', 'DOTNET_WATCH_HOTRELOAD_WEBSOCKET_ENDPOINT')->'%(Value)')</_AndroidWebSocketEndpoint> <_AndroidWebSocketPort>$([System.Text.RegularExpressions.Regex]::Match('$(_AndroidWebSocketEndpoint)', ':(\d+)').Groups[1].Value)</_AndroidWebSocketPort> ~~ Prevent Startup Hooks in Microsoft.Android.Run ~~ When I was implementing this, I keep seeing *two* clients connect to `dotnet-watch` and I was pulling my hair to figure out why! Then I realized that `Microsoft.Android.Run` was also getting `$DOTNET_STARTUP_HOOKS`, and so we had a desktop process + mobile process both trying to connect! Easiest fix, is to disable startup hook support in `Microsoft.Android.Run`. I reviewed the code in `dotnet run`, and it doesn't seem correct to try to clear the env vars. ~~ Conclusion ~~ With these changes, everything is working! dotnet watch 🔥 C# and Razor changes applied in 23ms.
jonathanpeppers
requested review from
grendello and
simonrozsival
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Pull request overview
Backport of .NET SDK dotnet run -e / dotnet watch behaviors into .NET for Android (.NET 11) by flowing @(RuntimeEnvironmentVariable) into the Android environment file, adding Hot Reload wiring (startup hook deployment + adb reverse), and extending device tests to validate the scenarios end-to-end.
Changes:
- Add
@(RuntimeEnvironmentVariable)support sodotnet run -e NAME=VALUEis written into the app’s generated environment file. - Add
dotnet watchHot Reload support by deploying the startup hook assembly, rewritingDOTNET_STARTUP_HOOKSfor Android, and configuringadb reversebased on the websocket endpoint env var. - Add/extend device integration tests and test infrastructure (
DotNetCLI,ProjectBuilder) to exercisedotnet run -eanddotnet watchhot reload.
Reviewed changes
Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| tests/MSBuildDeviceIntegration/Tests/InstallAndRunTests.cs | Adds device tests for dotnet watch hot reload and dotnet run -e environment variable propagation; adjusts run property passing. |
| src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets | Writes @(RuntimeEnvironmentVariable) into __environment__.txt and ensures Hot Reload env adjustments happen first. |
| src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Common/ProjectBuilder.cs | Exposes BuiltBefore to support external build flows like dotnet watch while still using ProjectTools file update infrastructure. |
| src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Common/DotNetCLI.cs | Adds StartWatch() and changes Run/StartRun parameter handling to allow passing non-MSBuild args (e.g. -e). |
| src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.ProjectCapabilities.targets | Advertises new project capabilities needed by the .NET SDK (RuntimeEnvironmentVariableSupport, HotReloadWebSockets). |
| src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.HotReload.targets | New targets to rewrite startup hook env var, deploy the delta applier assembly, and set up adb reverse. |
| src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.BuildOrder.targets | Hooks Hot Reload port forwarding and environment file generation into install/deploy target ordering. |
| src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.AssemblyResolution.targets | Ensures Hot Reload startup hook assembly is included in files to publish/deploy. |
| src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Application.targets | Refactors _AdbToolPath computation into _AndroidAdbToolPath target for reuse. |
| src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.After.targets | Imports the new Hot Reload targets for Android application projects. |
| src/Microsoft.Android.Run/Microsoft.Android.Run.csproj | Disables startup hook support to avoid host-side startup hooks interfering with device Hot Reload. |
| Documentation/docs-mobile/building-apps/build-items.md | Documents @(RuntimeEnvironmentVariable) usage and the dotnet run -e integration. |
| .github/copilot-instructions.md | Documents test best-practice for modifying project files via ProjectTools (Touch + Save). |
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| <Exec Condition=" '$(_AndroidWebSocketPort)' != '' " | ||
| Command=""$(_AdbToolPath)" reverse tcp:$(_AndroidWebSocketPort) tcp:$(_AndroidWebSocketPort)" /> |
When multiple devices/emulators are connected, the adb reverse command needs (e.g. -s emulator-5554) to target the correct device. Without it, the command fails with 'more than one device' or forwards on the wrong device. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Backport of:
@(RuntimeEnvironmentVariable)items #10770dotnet watchsupport, based on env vars #10778