Guide for MSBuild extensibility: CustomBefore/CustomAfter hooks, wildcard imports with alphabetic ordering, import gating with control properties, NuGet package build extension layout (build/buildTransitive), and the MicrosoftCommonPropsHasBeenImported guard. Only activate in MSBuild/.NET build context. USE FOR: diagnosing and fixing MSBuild import and hook patterns, reviewing and fixing extension point anti-patterns in Directory.Build files, fixing missing Exists() guards on imports that break fresh clones, fixing NuGet package hooks being silently dropped instead of appended, making build targets extensible for other projects, injecting custom logic into the build pipeline, creating NuGet packages that extend the build, conditionally disabling imports. DO NOT USE FOR: target authoring patterns (use target-authoring), props vs targets placement (use directory-build-organization), general anti-patterns (use msbuild-antipatterns), non-MSBuild build systems.
Instrucciones de origen · Vista previa de solo lectura
name
extension-points
description
Guide for MSBuild extensibility: CustomBefore/CustomAfter hooks, wildcard imports with alphabetic ordering, import gating with control properties, NuGet package build extension layout (build/buildTransitive), and the MicrosoftCommonPropsHasBeenImported guard. Only activate in MSBuild/.NET build context. USE FOR: diagnosing and fixing MSBuild import and hook patterns, reviewing and fixing extension point anti-patterns in Directory.Build files, fixing missing Exists() guards on imports that break fresh clones, fixing NuGet package hooks being silently dropped instead of appended, making build targets extensible for other projects, injecting custom logic into the build pipeline, creating NuGet packages that extend the build, conditionally disabling imports. DO NOT USE FOR: target authoring patterns (use target-authoring), props vs targets placement (use directory-build-organization), general anti-patterns (use msbuild-antipatterns), non-MSBuild build systems.
license
MIT
MSBuild Extension Points
How the MSBuild pipeline provides hooks for SDKs, NuGet packages, repos, and users to inject custom logic.
<ImportProject="$(CustomBeforeMicrosoftCommonTargets)"Condition="'$(CustomBeforeMicrosoftCommonTargets)' != '' and Exists('$(CustomBeforeMicrosoftCommonTargets)')"/>
<!-- ... core targets ... -->
<ImportProject="$(CustomAfterMicrosoftCommonTargets)"Condition="'$(CustomAfterMicrosoftCommonTargets)' != '' and Exists('$(CustomAfterMicrosoftCommonTargets)')"/>
Rules
Default path includes version (v$(MSBuildToolsVersion)) for side-by-side installations.
Always check Exists(). The file may not be present on every machine.
Append to the property (don't overwrite) to chain multiple hooks:
NuGet packages inject build logic via build/ or buildTransitive/ folders:
MyPackage/
build/
MyPackage.props ← imported via *.props wildcard
MyPackage.targets ← imported via *.targets wildcard
buildTransitive/
MyPackage.props ← imported by transitive consumers
MyPackage.targets
Rules
File names must match the package ID exactly.
build/ affects direct consumers only. buildTransitive/ affects the entire dependency chain.
Props are imported early (before the project), targets are imported late (after the project).
Import Guard Pattern
The .targets file ensures .props was imported using a guard property:
<!-- End of Microsoft.Common.props --><PropertyGroup><MicrosoftCommonPropsHasBeenImported>true</MicrosoftCommonPropsHasBeenImported></PropertyGroup><!-- Top of Microsoft.Common.CurrentVersion.targets --><ImportProject="Microsoft.Common.props"Condition="'$(MicrosoftCommonPropsHasBeenImported)' != 'true'" />
This handles projects that only import .targets.
Directory.Build Discovery
MSBuild walks up the directory tree to find the nearest Directory.Build.props:
