[Repo] Attempting to stabilize the API Compatibility CI job (#3766)

* Attempting to stablize the API Compatibility CI.

* Tweak.

* More logging.

* Increase build logging level for api compat ci job.

* Tweak.

* Tweak.

* Revert extra logging in ci job.

* Switched some logging back to debug.

build/Common.prod.props

@@ -13,11 +13,17 @@
 
   <ItemGroup Condition="'$(MinVerTagPrefix)' == 'core-' AND '$(CheckAPICompatibility)' == 'true'">
     <PackageReference Include="Microsoft.DotNet.ApiCompat" Version="6.0.0-beta.21308.1" PrivateAssets="All" />
-    <ResolvedMatchingContract Include="..\LastMajorVersionBinaries\$(AssemblyName)\$(OTelPreviousStableVer)\lib\$(TargetFramework)\$(AssemblyName).dll" />
+    <ResolvedMatchingContract Include="$(RepoRoot)\build\LastMajorVersionBinaries\$(AssemblyName)\$(OTelPreviousStableVer)\lib\$(TargetFramework)\$(AssemblyName).dll" />
   </ItemGroup>
 
-  <Target Name="PreBuild" BeforeTargets="PreBuildEvent" Condition="'$(MinVerTagPrefix)' == 'core-' AND '$(CheckAPICompatibility)' == 'true'">
-    <Exec Command="powershell -ExecutionPolicy Unrestricted -File &quot;$(RepoRoot)\build\PreBuild.ps1&quot; -package $(AssemblyName) -version &quot;$(OTelPreviousStableVer)&quot;" />
+  <Target Name="PreBuild" BeforeTargets="DispatchToInnerBuilds;ValidateApiCompatForSrc" Condition="'$(MinVerTagPrefix)' == 'core-' AND '$(CheckAPICompatibility)' == 'true'">
+    <!-- Note: DispatchToInnerBuilds is called for projects with multiple
+    targets defined to spawn a build process for each target framework being
+    compiled. Executing BEFORE that step means this runs once for a project
+    instead of in parallel for each target framework defined. If we ever have a
+    project with only a single target, this will NOT run and an alternative
+    solution will be needed. -->
+    <Exec Command="powershell -ExecutionPolicy Unrestricted -File &quot;$(RepoRoot)\build\PreBuild.ps1&quot; -package $(AssemblyName) -version &quot;$(OTelPreviousStableVer)&quot; -workDir &quot;$(RepoRoot)\build\LastMajorVersionBinaries&quot;" />
   </Target>
 
   <Target Name="FindContractDependencyPaths" BeforeTargets="ValidateApiCompatForSrc" AfterTargets="ResolveAssemblyReferences" Condition="'$(MinVerTagPrefix)' == 'core-' AND '$(CheckAPICompatibility)' == 'true'">

build/PreBuild.ps1

@@ -1,26 +1,31 @@
-param([string]$package, [string]$version)
+param(
+  [string]$package,
+  [string]$version,
+  [string]$workDir = ".\LastMajorVersionBinaries"
+)
 
-$workDir = "..\LastMajorVersionBinaries"
 if (-Not (Test-Path $workDir))
 {
-    Write-Host "Working directory for previous package versions not found, creating..."
+    Write-Host "Working directory for compatibility check packages '$workDir' not found, creating..."
     New-Item -Path $workDir -ItemType "directory" | Out-Null
 }
 
 if (Test-Path -Path "$workDir\$package.$version.zip")
 {
-    Write-Debug "Previous package version already downloaded"
+    Write-Debug "Previous package $package@$version already downloaded for compatibility check"
 }
 else
 {
-    Write-Host "Retrieving $package @$version for compatibility check"
+    Write-Host "Retrieving package $package@$version for compatibility check"
     Invoke-WebRequest -Uri https://www.nuget.org/api/v2/package/$package/$version -Outfile "$workDir\$package.$version.zip"
 }
+
 if (Test-Path -Path "$workDir\$package\$version\lib")
 {
-    Write-Debug "Previous package version already extracted"
+    Write-Debug "Previous package $package@$version already extracted to '$workDir\$package\$version\lib'"
 }
 else
 {
+    Write-Host "Extracting package $package@$version from '$workDir\$package.$version.zip' to '$workDir\$package\$version' for compatibility check"
     Expand-Archive -LiteralPath "$workDir\$package.$version.zip" -DestinationPath "$workDir\$package\$version" -Force
 }