InstallOrUpdateSolution.ps1

Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"
Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Publishing.dll"

#Utility function to authenticate CSOM and return the Client Context
Function Authenticate-CSOM($siteUrl, $adminUsername, $secureAdminPassword) {
	$ctx = New-Object Microsoft.SharePoint.Client.ClientContext($siteUrl) 
	$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($adminUsername, $secureAdminPassword)
	$ctx.Credentials = $credentials
	return $ctx
}

Function InstallOrUpdateSolution($SiteUrl , $wspFullFilePath, $WspFileName, $wspPackageName, $majorVersion, $minorVersion, $scAdminUsername, $secureAdminPassword){

	$ctx = Authenticate-CSOM $SiteUrl $scAdminUsername $secureAdminPassword
	
	#Upload wsp to Solution Gallery
	Write-Host "Uploading file to Solution Gallery"
	
	$solutionGallery =  $ctx.Web.Lists.GetByTitle("Solution Gallery")
	$solutionGalleryRootFolder = $solutionGallery.RootFolder
	$ctx.Load($solutionGallery)
	$ctx.Load($solutionGallery.RootFolder)
	$ctx.ExecuteQuery()
	
	$wspfileStream = New-Object System.IO.FileStream($wspFullFilePath, [System.IO.FileMode]::Open)
	
	#Create the FileCreationInformation object and prepare to upload it to the solution gallery
	$fileCI = New-Object Microsoft.SharePoint.Client.FileCreationInformation
	$fileCI.Overwrite = $true
	$fileCI.ContentStream = $wspfileStream
	$fileCI.URL = $WspFileName
	
	#upload the solution to the gallery
	$uploadedFile = $solutionGallery.RootFolder.Files.Add($fileCI);
	$ctx.Load($uploadedFile);
	$ctx.ExecuteQuery();
	Write-Host "done"
	
	#Install the solution
	Write-Host "Installing solution"
	
	#Create the DesignPackageInfo object 
	$wsp = New-Object Microsoft.SharePoint.Client.Publishing.DesignPackageInfo
	$wsp.PackageGuid = [System.Guid]::Empty
	$wsp.PackageName = $wspPackageName 
	$wsp.MajorVersion = $majorVersion
	$wsp.MinorVersion = $minorVersion
	
	#Install the solution from the file url
	$filerelativeurl = $solutionGallery.RootFolder.ServerRelativeUrl + "/" + $WspFileName;
	[Microsoft.SharePoint.Client.Publishing.DesignPackage]::Install($ctx, $ctx.Site, $wsp, $filerelativeurl)
	$ctx.ExecuteQuery()
	Write-Host "done"
	
	#Apply/Activate the solution
	Write-Host "Applying solution"
	[Microsoft.SharePoint.Client.Publishing.DesignPackage]::Apply($ctx, $ctx.Site, $wsp);
	$ctx.ExecuteQuery()
	Write-Host "done"
	
	#The Install and Apply methods create a copy of the solution. This copy is renamed according to the Major and Minor Version specified in the DesignPackageInfo object. 
	#Once this copy is activated, we no longer need the original wsp file uploaded to the solution gallery.
	Write-Host "Deleting temporary files"
	$uploadedSolutionFile = $solutionGallery.rootFolder.Files.GetByUrl($filerelativeurl);
	$uploadedSolutionFile.DeleteObject();
	$ctx.ExecuteQuery()
	Write-Host "done"
}