Powershell script to dynamically set .NET Assembly/DLL versions for git

How can you dynamically set a C# .net project assembly (dll) version attributes on a build server specifially for git version control?

A simple solution is to just use a powershell script on the build server to change all the AssemblyVersion attributes on the fly right before compiling the solution. This requires no special dev tooling or msbuild changes and you can utilize the popular practice of git tags for release/version tagging.

.NET Project Versioning

Our script will target the following attributes in the properties > AssemblyInfo.cs file.

[assembly: AssemblyVersion("0.0.0.0")]
[assembly: AssemblyFileVersion("0.0.0.0")]

Powershell script details

Our script will:

1. Query git for the latest version tag and number of commits on the branch
2. Find all the AssemblyInfo.cs files and just use regex to swap in our versions
3. Build the solution

Some assumptions for this method:

• The version parser expects you have already tagged your git repo with a version. For example: git tag -l "v2.0.0" and be sure to push the tag.
• I use git describe --long --tags --always to get the most recent tag and the number of commits. I use the number of commits to easily track incremental changes for devs and QA.
• The regex expects either a 3 or 4 digit version number already exists in your AssemblyInfo.cs file.
• In Bamboo Build server make sure you are not using "Shallow Clones" for the repo. They will not include the git tags.

Powershell script to dynamically change AssemblyInfo.cs Files

The script can easily be tailored to fit your needs. As a powershell amateur I just did the bare minimum to get the script working.

View as Gist or the code below:

function getVersion()
{
    $tag = iex "git describe --long --tags --always"
    $a = [regex]"v\d+\.\d+\.\d+\-\d+"
    $b = $a.Match($tag)
    $b = $b.Captures[0].value
    $b = $b -replace '-', '.'
    $b = $b -replace 'v', ''
    Write-Host "Version found: $b"
    return $b
}


function SetVersion ($file, $version)
{

    "Changing version in $file to $version"
    $fileObject = get-item $file
    #$fileObject.Set_IsReadOnly($False)

    $sr = new-object System.IO.StreamReader( $file, [System.Text.Encoding]::GetEncoding("utf-8") )
    $content = $sr.ReadToEnd()
    $sr.Close()

    $content = [Regex]::Replace($content, "(\d+)\.(\d+)\.(\d+)[\.(\d+)]*", $version);

    $sw = new-object System.IO.StreamWriter( $file, $false, [System.Text.Encoding]::GetEncoding("utf-8") )
    $sw.Write( $content )
    $sw.Close()
    #$fileObject.Set_IsReadOnly($True)
}

function setVersionInDir($dir, $version) {

    if ($version -eq "") {
        Write-Host "version not found"
        exit 1
    }

    # Set the Assembly version
    $info_files = Get-ChildItem $dir -Recurse -Include "AssemblyInfo.cs" | where {$_ -match 'my.namespace'}
    foreach($file in $info_files)
    {
        Setversion $file $version
    }
}

# First get tag from Git
$version = getVersion
$dir = "./"
setVersionInDir $dir $version

Other Solutions

• Use a MSBuild Community Task that requires remembering to manually edit the .csproj file.