Sample PowerShell script to create Azure Automation runbook webhook that is targeting a Hybrid Worker group

New-AAWebhookRunOnHybridWorkerGroup.ps1

#Function to generate Azure AD authorization token for the ARM rest API
Function Get-AADToken {
       
  [CmdletBinding()]
  [OutputType([string])]
  PARAM (
    [Parameter(Position=0,Mandatory=$true)]
    [ValidateScript({
          try 
          {
            [System.Guid]::Parse($_) | Out-Null
            $true
          } 
          catch 
          {
            $false
          }
    })]
    [Alias('tID')]
    [String]$TenantID,

    [Parameter(Position=1,Mandatory=$true)][Alias('cred')]
    [pscredential]
    [System.Management.Automation.CredentialAttribute()]
    $Credential,
    
    [Parameter(Position=0,Mandatory=$false)][Alias('type')]
    [ValidateSet('UserPrincipal', 'ServicePrincipal')]
    [String]$AuthenticationType = 'UserPrincipal'
  )
  Try
  {
    $Username       = $Credential.Username
    $Password       = $Credential.Password

    If ($AuthenticationType -ieq 'UserPrincipal')
    {
      # Set well-known client ID for Azure PowerShell
      $clientId = '1950a258-227b-4e31-a9cf-717495945fc2'

      # Set Resource URI to Azure Service Management API
      $resourceAppIdURI = 'https://management.azure.com/'

      # Set Authority to Azure AD Tenant
      $authority = 'https://login.microsoftonline.com/common/' + $TenantID
      Write-Verbose "Authority: $authority"

      $AADcredential = [Microsoft.IdentityModel.Clients.ActiveDirectory.UserCredential]::new($UserName, $Password)
      $authContext = [Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext]::new($authority)
      $authResult = $authContext.AcquireTokenAsync($resourceAppIdURI,$clientId,$AADcredential)
      $Token = $authResult.Result.CreateAuthorizationHeader()
    } else {
      # Set Resource URI to Azure Service Management API
      $resourceAppIdURI = 'https://management.core.windows.net/'

      # Set Authority to Azure AD Tenant
      $authority = 'https://login.windows.net/' + $TenantId

      $ClientCred = [Microsoft.IdentityModel.Clients.ActiveDirectory.ClientCredential]::new($UserName, $Password)
      $authContext = [Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext]::new($authority)
      $authResult = $authContext.AcquireTokenAsync($resourceAppIdURI,$ClientCred)
      $Token = $authResult.Result.CreateAuthorizationHeader()
    }
    
  }
  Catch
  {
    Throw $_
    $ErrorMessage = 'Failed to aquire Azure AD token.'
    Write-Error -Message 'Failed to aquire Azure AD token'
  }

  $Token
}
#Variables for your Azure subscription and Automation Account
$subscriptionId = 'specify-your-subscription-id'
$AADTenantId = 'specify-your-AAD-tenant-id'
$resourceGroup = 'specify-resource-group-name-for-azure-automation-account'
$automationAccount = 'specify-azure-automation-account-name'
$HybridWorkerGroup = 'specify-hybrid-worker-group-name'

#Specify an organization account to sign in to Azure (using AAD token)
$AzureAdminUserName = 'admin@yourcompany.onmicrosoft.com'
$AzureAdminPassword = Read-Host "Enter password for $AzureAdminUserName" -AsSecureString
$AzureAdminCred = New-object System.Management.Automation.PSCredential($AzureAdminUserName, $AzureAdminPassword)

#Generate AAD token and construct HTTP request header
$AADToken = Get-AADToken -TenantID $AADTenantId -Credential $AzureAdminCred
$RESTAPIHeaders = $RESTAPIHeaders = @{'Authorization'=$AADToken;'Accept'='application/json'; 'Content-Type'='application/json'}

#Specify Runbook information
$runbookName = 'HelloWorld'
$runbookParameters = @{
  Name = 'Tao'
}
$webhookName = "$runbookName_$HybridWorkerGroup"

#Generate webhook URI


$GenerateWebhookURIRequestURI = "https://management.azure.com/subscriptions/$subscriptionId/resourceGroups/$resourceGroup/providers/Microsoft.Automation/automationAccounts/$automationAccount/webhooks/generateUri?api-version=2015-10-31"
$WebhookUriRequest = Invoke-WebRequest -UseBasicParsing -Uri $GenerateWebhookURIRequestURI -Method Post -Headers $RESTAPIHeaders
If ($WebhookUriRequest.StatusCode -ge 200 -and $WebhookUriRequest.StatusCode -le 299)
{
  #request successful
  $WebhookUri = ($WebhookUriRequest.Content.TrimStart('"')).trimEnd('"')
} else {
  Throw "Failed to generate the webhook URI."
}

#Create webhook that expires in 10 years
$UTCNow = [Datetime]::UtcNow
$webhookExpiryDate = $UTCNow.AddYears(10)
$NewWebHookRequestURI = "https://management.azure.com/subscriptions/$subscriptionId/resourceGroups/$resourceGroup/providers/Microsoft.Automation/automationAccounts/$automationAccount/webhooks/$webhookName`?api-version=2015-10-31"
$webhookrequestbody = @{
  name = $webhookName
  properties = @{
    isEnabled = $true 
    Uri = $webhookuri
    expiryTime = $webhookExpiryDate
    runbook = @{
      name = $runbookName
    }
    runOn = $HybridWorkerGroup
    parameters = $runbookParameters
  }
}
$webhookrequestbodyjson = $webhookrequestbody | ConvertTo-Json
$NewWebhookRequest = Invoke-WebRequest -UseBasicParsing -Uri $NewWebHookRequestURI -Headers $RESTAPIHeaders -Method Put -Body $webhookrequestbodyjson

If ($NewWebhookRequest.StatusCode -ge 200 -and $NewWebhookRequest.StatusCode -le 299)
{
  Write-Output "Webhook created. URL: '$webookuri'"
} else {
  Throw "Failed to create the webhook."
}