Get HTTP request and tolerate 500 server error in powershell - powershell

Question

In Powershell v3.0 I would like to return the response code from an HTTP GET, such as 200 OK or 500 Internal Server Error. (This is for a hack-deploy to do a quick warmup of a deployed site and see if it works, a sort of a mini acceptance test. The status code is truly all I want.)
Against my wishes, HttpWebRequest.GetResponse throws an error when it receives a 500 Internal Server Error. This is annoying because it isn't really an error to me in my use case. Anyway, I figured I could catch the exception and still peel out the underlying response code, but I'm having trouble with that.
Here's some almost-working code:
function WebResponseStatusCode (
[Parameter(Mandatory=$true)][string] $url
) {
$req = [system.Net.HttpWebRequest]::Create($url)
try {
$res = $req.GetResponse();
$statuscode = $res.statuscode;
}
catch [System.Net.WebException] {
#the outer error is a System.Management.Automation.ErrorRecord
Write-Host "error!"
return = $_.Response.statuscode; #nope
}
finally {
if (!($res -eq $null)) {
$res.Close();
}
}
return $statuscode;
}
The problem is of course that $_ has no Response property. Neither does $_.InnerException, even when cast:
return [System.Net.WebException]($_.InnerException)
I've played around with $_ | Get-Member and exploring all its properties. I thought $_.TargetObject had some promise but it doesn't appear to.
(Update) I also think I tried variations on $_.Exception.Response though may have gotten it wrong.
Getting just a response code seems like such a simple thing to do.

Answer 1

Here's an example, though it does a couple more things to allow you to test redirections as well as expected exceptions.
function GetWebSiteStatusCode {
param (
[string] $testUri,
$maximumRedirection = 5
)
$request = $null
try {
$request = Invoke-WebRequest -Uri $testUri -MaximumRedirection $maximumRedirection -ErrorAction SilentlyContinue
}
catch [System.Net.WebException] {
$request = $_.Exception.Response
}
catch {
Write-Error $_.Exception
return $null
}
$request.StatusCode
}
GetWebSiteStatusCode -testUri "https://www.google.com/"
GetWebSiteStatusCode -testUri "https://www.google.com/foobar"
GetWebSiteStatusCode -testUri "http://google.com/" -maximumRedirection 0
GetWebSiteStatusCode -testUri "https://accounts.google.com" -maximumRedirection 0
GetWebSiteStatusCode -testUri "https://www.googleapis.com/coordinate/v1/teams/1/custom_fields?fields=1111&key="
GetWebSiteStatusCode -testUri "https://www.googleapis.com/shopping/search/v1/test/products/sasdf/asdf/asdf?key="
#Next test would be for an expected 500 page.
#GetWebSiteStatusCode -testUri "https://www.somesite.com/someurlthatreturns500"