Don't publish to NuGet if the version has already been published

Author: carolynvs

build/appveyor-deploy-docs.ps1

@@ -74,9 +74,16 @@
     <Exec Command="$(NuGet) pack ..\src\corelib\corelib.nuspec -OutputDirectory ..\artifacts\packages -Prop Configuration=$(Configuration) -Version $(Version) -Symbols" />
   </Target>
 
-  <Target Name="Publish" DependsOnTargets="DownloadNuGet">
+  <Target Name="PublishNuGet" DependsOnTargets="DownloadNuGet">
+    <Exec Command="@powershell -NoProfile -ExecutionPolicy unrestricted -File check-nuget-version-exists.ps1 $(Version)" ConsoleToMSBuild="true">
+      <Output TaskParameter="ConsoleOutput" PropertyName="ShouldPublishToNuGet" />
+    </Exec>
+
     <!-- The environment variable BAMBOO_NUGET_PASSWORD comes from the nuget.password variable defined on the openstack.net plan in Bamboo -->
-    <Exec Command="$(NuGet) push ..\artifacts\packages\openstack.net.$(Version).nupkg %25BAMBOO_NUGET_PASSWORD%25" />
+    <Message Text="Skipping publish to NuGet because version $(Version) has already been published."
+          Condition=" '$(ShouldPublishToNuGet)' == 'False' " />
+    <Exec Command="$(NuGet) push ..\artifacts\packages\openstack.net.$(Version).nupkg %25BAMBOO_NUGET_PASSWORD%25"
+          Condition=" '$(ShouldPublishToNuGet)' == 'True' " />
   </Target>
 
 </Project>

build/build.proj

@@ -0,0 +1,13 @@
+param (
+  [string]$version
+)
+
+try {
+  $url = "http://nuget.org/packages/openstack.net/$version"
+  $status = (Invoke-WebRequest $url).StatusCode
+} catch {
+  $status = $_.Exception.Response.StatusCode.Value__
+}
+
+$shouldPublishToNuGet = $status -eq '404'
+Write-Host $shouldPublishToNuGet