invoke-webrequest returns 401 with Windows Authentication - powershell

Question

I'm working on a script to login to a sharepoint 2013 site and navigate to a few pages to make sure the site is working after updates and DR drills. I'm calling Invoke-WebRequest like this:
$site = Invoke-WebRequest -uri 'https://spsite' -Credential $(Get-Credential) -SessionVariable s
when I make the call I get a 401 Unauthorized error back. I have tried using basic authentication and building out the headers like this:
$u = 'domain\user'
$p = 'password'
$header = #{ Authorization = "Basic {0}" -f [convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $u,$p))) }
$site = Invoke-WebRequest -uri 'https://spsite' -Headers $header
with the same result. I'm hoping someone could offer another way to make this connection?

Answer 1

so I found a way to make this work in my situation and wanted to post the basics in case someone else runs into this.
I found that when the exception is thrown you can get the actual response from the web server from the exception object like this:
try{
$site = Invoke-WebRequest -uri 'https://spsite' -Credential $(Get-Credential) -SessionVariable s
}
catch{
$site = $_.Exception.Response
}
after that I was able to manipulate the $site variable to follow the redirection and submit the credentials as needed.

Answer 2

Use Export-PSCredential and Import-PSCredential from WFTools - you'll only have to enter your credentials once per box, and it will last as long as your password doesn't change: https://github.com/RamblingCookieMonster/PowerShell
Install-Module -Name WFTools -RequiredVersion 0.1.44
Import-Module WFTools;
$getCredentialMessage = "Please provide your Windows credentials";
$importedCredential = Import-PSCredential;
if ($importedCredential) {
Write-Host -ForegroundColor Yellow "Imported your cached credential."
while (-not $(Test-Credential -Credential $credential)) {
Write-Host -ForegroundColor Yellow "Your cached credentials are not valid. Please re-enter."
$credential = Get-Credential -Message $getCredentialMessage;
}
$credential = $importedCredential;
}
else {
$credential = Get-Credential -Message $getCredentialMessage;
while (-not $(Test-Credential -Credential $credential)) {
$credential = Get-Credential -Message $getCredentialMessage;
}
Export-PSCredential $credential;
}
# Here is where the magic happens
$site = Invoke-WebRequest -uri 'https://spsite' -Credential $credential