Updating multiple site bindings in IIS with new SSL-certificate

Octopus-Update-Certificates.ps1

# Example of usage:
# Update-Certificates -domainNameMatchPattern "mycompany.com" -variableNameForCertificateToUse "CurrentMyCompanyDotComCertificate"

function Write-Info ($message) {
    Write-Host "Info:" $message
}

function AssignCertificate([string] $friendlyName, [string] $hostName, [int] $port) {
	$matchingCertificates = (Get-ChildItem cert:\localmachine\my) | Where-Object {$_.FriendlyName -eq $friendlyName}
	$matchCount = ($matchingCertificates | Measure-Object).Count
	if ($matchCount -ne 1) {
		Write-Info ("Found " + $matchCount + " certificates matching friendly name " + $friendlyName + " (Expecting 1 match).")
		Write-Info "The following certificates are installed: "
		(Get-ChildItem cert:\localmachine\my) | Format-Table -Property Thumbprint, FriendlyName, Subject
	}
	else {
		$certificate = $matchingCertificates[0]
		
		$existingBinding = Get-WebBinding | Where-Object { $_.bindingInformation -match ":$($port):$($hostName)" }
		if ($existingBinding) {
			if ($existingBinding.certificateHash -ne $certificate.Thumbprint) {
				Write-Info "Found existing binding with different thumbprint $($certificate.Thumbprint), will remove old certificate binding"
				"netsh http delete sslcert hostnameport=$($hostName):$($port)"
				$command = "& netsh.exe http delete sslcert hostnameport=$($hostName):$($port)"
				Write-Info "Executing: $command"
				Invoke-Expression $command
			}
			else {
				return
			}
		}
		
		$appIdGuid = [guid]::NewGuid().ToString("B")
		$command = "& netsh.exe http add sslcert hostnameport=$($hostName):$($port) certhash=$($certificate.Thumbprint) certstorename=MY appid='$($appIdGuid)' "
		Write-Info "Executing: $command"
		Invoke-Expression $command
	}
}

function Update-Certificates([string] $domainNameMatchPattern, [string] $variableNameForCertificateToUse)
{
	Write-Info "Update-Certificates starting"
	$certificateFriendlyName = $OctopusParameters["$($variableNameForCertificateToUse).Name"]
	Write-Info "Certificate variable name is $certificateFriendlyName"

	Import-Module WebAdministration
	
	$bindingsToUpdate = Get-WebBinding | Where-Object { $_.protocol -eq "https" -and $_.bindingInformation -match $domainNameMatchPattern }
	Write-Info "Found $($bindingsToUpdate.Length) binding(s) to update:"
	Write-Info $bindingsToUpdate 
	
	[regex]$bindingInfoRegEx = "\*:(?<portNo>\d+):(?<hostName>.+)"
	
	foreach ($binding in $bindingsToUpdate) {
		$bindingInfoMatch = $bindingInfoRegEx.Match($binding.bindingInformation)
		[int]$portNo = $bindingInfoMatch.Groups["portNo"].Value
		$hostName = $bindingInfoMatch.Groups["hostName"].Value
		AssignCertificate -friendlyName $certificateFriendlyName -hostName $hostName -port $portNo
	}
}

Read blog post for this script at https://blog.hundeide.net/2017/12/updating-multiple-site-bindings-in-iis-with-new-ssl-certificate/