Add Variable Sets to all projects

AddVariableSetsToAllProjects.ps1

$OctopusAPIkey = "" #Octopus API Key to authenticate
$OctopusURL = "" #Octopus Server URL

$variableSetId = "" #Variable Set Id you want to add to projects

#Register the Octopus client and Newtonsoft JSON dlls for all this to work
Add-Type -Path "C:\Program Files\Octopus Deploy\Octopus\Newtonsoft.Json.dll"
Add-Type -Path "C:\Program Files\Octopus Deploy\Octopus\Octopus.Client.dll"

#Create a connection to the Octopus server using the URL and the API Key
$endpoint = new-object Octopus.Client.OctopusServerEndpoint "$($OctopusURL)","$($OctopusAPIKey)"
$repository = new-object Octopus.Client.OctopusRepository $endpoint

#Getting all projects
$allProjects = $repository.projects.findAll()

foreach($project in $allProjects) {
    #Add the variable set to the project using the ID
    $project.IncludedLibraryVariableSetIds.Add($variableSetId)

    #Save the changes to the project on the database
    $repository.Projects.Modify($project)
}