CreateAssemblyInfoFromGit

CreateAssemblyInfoFromGit is a MSBuild task creating a CommonAssemblyInfo.cs based on the git repository.

The goal is to create a predictable version schema for your project. The generated versions follow Semantic Versioning with some restrictions required by NuGet.

How the version is determined

vX.Y

CreateAssemblyInfoFromGit walks the commits backwards until it finds a tag with the format vX.Y. It takes this version and appends the distance to HEAD as the build number, e.g. the number of commits since the tag. With this information it generates a file named CommonAssemblyInfo.cs in the solution folder. E.g. if you have a tag named v1.0, six commits later the MSBUild task would write following content to CommonAssemblyInfo.cs:

// Generated: 05/31/2013 16:51:56 (UTC)
// Warning: This is generated code! Don't touch as it will be overridden by the build process.

using System.Reflection;

[assembly: AssemblyVersion("1.0.6.0")]
[assembly: AssemblyFileVersion("1.0.6.0")]
[assembly: AssemblyInformationalVersion("1.0.6")]

The major and minor components of the version are determined by the tag, the build component is the number of commits since the tag.

If the HEAD is tagged with vX.Y, the release component is the number of commits since the previous vNext-X.Y tag; otherwise, it is 0. This is to guarantee that versions are always increasing. See the line with the v-1.0 tag in the table below: The file version of the v1.0 release is greater than the beta version before.

vNext-X.Y

However, it gets more interesting when you plan a new release for your software. If for example the next release would be 2.0, you create a tag named like vNext-2.0. Three commits later, the task would create this CommonAssemblyInfo.cs:

// Generated: 05/31/2013 16:55:17 (UTC)
// Warning: This is generated code! Don't touch as it will be overridden by the build process.

using System.Reflection;

[assembly: AssemblyVersion("2.0.0.3")]
[assembly: AssemblyFileVersion("2.0.0.3")]
[assembly: AssemblyInformationalVersion("2.0.0-beta0003")]

Here the major and minor components of the version are determined by the tag, the build component is 0, and the release component is the number of commits since the tag.

Example

Here's a table how I test the version generation. Each row represents a commit with optional tags attached:

Tags              File     Display         Description
-----------------------------------------------------------------------------
                  0.0.0.0  0.0.0-beta0000  
                  0.0.0.1  0.0.0-beta0001  
vNext-1.0         1.0.0.0  1.0.0-beta0000  Started working on v1.0
                  1.0.0.1  1.0.0-beta0001
                  1.0.0.2  1.0.0-beta0002
v-1.0             1.0.0.3  1.0.0           Release v1.0
                  1.0.1.0  1.0.1
                  1.0.2.0  1.0.2
vNext-1.1         1.1.0.0  1.1.0-beta0000  Next release will be 1.1
                  1.1.0.1  1.1.0-beta0001
v-1.1, vNext-1.2  1.1.0.2  1.1.0           Release v1.1, started working on v1.2
                  1.2.0.1  1.2.0-beta0001			

Usage

Just add the NuGet package CreateAssemblyInfoFromGit to your project. The package adds the CreateAssemblyInfoFromGit MSBuild task and a link to CommonAssemblyInfo.cs in the solution folder.

From now on whenever your project is built and there are new commits, CommonAssemblyInfo.cs will be updated.

Annotation

I would have prefered to generate prerelease versions as 0.0.0-beta.0, but unfortunately NuGet is not fully compliant with SemVer. NuGet does not allow the . behind the beta, and it sorts alphabetically (it's documented here). Therefore I had to skip the . and pad the prelease number with zeros.