.net – How to auto increment the C# assembly version via our CI platform (Hudson)

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Myself and my group are horrendous at incrementing assembly version numbers and we frequently ship assemblies with 1.0.0.0 versions. Obviously, this causes a lot of headaches.

We're getting a lot better with our practices via our CI platform and I'd really like to set it up to auto increment the values within the assemblyinfo.cs file so that the versions of our assemblies are auto updated with the code changes in that assembly.

I had previously setup (before we found Hudson) a way to increment the value through either msbuild or the command line (can't remember), but with Hudson, that will update the SVN repository and trigger ANOTHER build. That would result in a slow infinite loop as Hudson polls SVN every hour.

Is having Hudson increment the version number a bad idea? What would be an alternative way to do it?

Ideally, my criteria for a solution would be one that:

  • Increments the build number in assemblyinfo.cs before a build
  • Only increments the build number in assemblies that have changed. This may not be possible as Hudson wipes out the project folder every time it does a build
  • Commits the changed assemblyinfo.cs into the code repository (currently VisualSVN)
  • Does not cause Hudson to trigger a new build the next time it scans for changes

Working this out in my head, I could easily come up with a solution to most of this through batch files / commands, but all of my ideas would cause Hudson to trigger a new build the next time it scans. I'm not looking for someone to do everything for me, just point me in the right direction, maybe a technique to get Hudson to ignore certain SVN commits, etc.

Everything I've found so far is just an article explaining how to get the version number automatically incremented, nothing takes into account a CI platform that could be spun into an infinite loop.

Best Answer

Here's what I did, for stamping the AssemblyFileVersion attribute.

Removed the AssemblyFileVersion from AssemblyInfo.cs

Add a new, empty, file called AssemblyFileInfo.cs to the project.

Install the MSBuild community tasks toolset on the hudson build machine or as a NuGet dependency in your project.

Edit the project (csproj) file , it's just an msbuild file, and add the following.

Somewhere there'll be a <PropertyGroup> stating the version. Change that so it reads e.g.

 <Major>1</Major>
 <Minor>0</Minor>
 <!--Hudson sets BUILD_NUMBER and SVN_REVISION -->
 <Build>$(BUILD_NUMBER)</Build>
 <Revision>$(SVN_REVISION)</Revision>

Hudson provides those env variables you see there when the project is built on hudson (assuming it's fetched from subversion).

At the bottom of the project file, add

 <Import Project="$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets" Condition="Exists('$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets')" />
  <Target Name="BeforeBuild" Condition="Exists('$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets')">
    <Message Text="Version: $(Major).$(Minor).$(Build).$(Revision)" />
    <AssemblyInfo CodeLanguage="CS" OutputFile="AssemblyFileInfo.cs" AssemblyFileVersion="$(Major).$(Minor).$(Build).$(Revision)" AssemblyConfiguration="$(Configuration)" Condition="$(Revision) != '' " />
  </Target>

This uses the MSBuildCommunityTasks to generate the AssemblyFileVersion.cs to include an AssemblyFileVersion attribute before the project is built. You could do this for any/all of the version attributes if you want.

The result is, whenever you issue a hudson build, the resulting assembly gets an AssemblyFileVersion of 1.0.HUDSON_BUILD_NR.SVN_REVISION e.g. 1.0.6.2632 , which means the 6'th build # in hudson, buit from the subversion revision 2632.

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