Ensure pool doesn't already exist

Author: PaulStovell

examples/03-CreateAppPool/Web.ps1

@@ -16,39 +16,42 @@ New-Website -Name "Website1" -Port 80 -IPAddress "*" -HostHeader "" -PhysicalPat
 
 Import-Module WebAdministration
 
-New-Item -Path "IIS:\AppPools" -Name "My Pool 3" -Type AppPool
-
-# Older applications may require "Classic" mode, but most modern ASP.NET
-# apps use the integrated pipeline
-Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "managedPipelineMode" -value "Integrated"
-
-# What version of the .NET runtime to use. Valid options are "v2.0" and 
-# "v4.0". IIS Manager often presents them as ".NET 4.5", but these still 
-# use the .NET 4.0 runtime so should use "v4.0". 
-Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "managedRuntimeVersion" -value "v4.0"
-
-# If your ASP.NET app must run as a 32-bit process even on 64-bit machines
-# set this to $true. This is usually only important if your app depends 
-# on some unmanaged (non-.NET) DLL's. 
-Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "enable32BitAppOnWin64" -value $false
-
-# Starts the application pool automatically when a request is made. If you 
-# set this to false, you have to manually start the application pool or 
-# you will get 503 errors. 
-Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "autoStart" -value $true
-
-# "AlwaysRunning" = application pool loads when Windows starts, stays running
-# even when the application/site is idle. 
-# "OnDemand" = IIS starts it when needed. If there are no requests, it may 
-# never be started. 
-Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "startMode" -value "OnDemand"
-
-# What account does the application pool run as? 
-# "ApplicationPoolIdentity" = best
-# "LocalSysten" = bad idea!
-# "NetworkService" = not so bad
-# "SpecificUser" = useful if the user needs special rights
-Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "processModel.identityType" -value "ApplicationPoolIdentity"
+$pool = Get-Item -Path "IIS:\AppPools\My Pool 3" -ErrorAction SilentlyContinue
+if ($pool -eq $null) {
+    New-Item -Path "IIS:\AppPools" -Name "My Pool 3" -Type AppPool
+
+    # Older applications may require "Classic" mode, but most modern ASP.NET
+    # apps use the integrated pipeline
+    Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "managedPipelineMode" -value "Integrated"
+
+    # What version of the .NET runtime to use. Valid options are "v2.0" and 
+    # "v4.0". IIS Manager often presents them as ".NET 4.5", but these still 
+    # use the .NET 4.0 runtime so should use "v4.0". 
+    Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "managedRuntimeVersion" -value "v4.0"
+
+    # If your ASP.NET app must run as a 32-bit process even on 64-bit machines
+    # set this to $true. This is usually only important if your app depends 
+    # on some unmanaged (non-.NET) DLL's. 
+    Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "enable32BitAppOnWin64" -value $false
+
+    # Starts the application pool automatically when a request is made. If you 
+    # set this to false, you have to manually start the application pool or 
+    # you will get 503 errors. 
+    Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "autoStart" -value $true
+
+    # "AlwaysRunning" = application pool loads when Windows starts, stays running
+    # even when the application/site is idle. 
+    # "OnDemand" = IIS starts it when needed. If there are no requests, it may 
+    # never be started. 
+    Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "startMode" -value "OnDemand"
+
+    # What account does the application pool run as? 
+    # "ApplicationPoolIdentity" = best
+    # "LocalSysten" = bad idea!
+    # "NetworkService" = not so bad
+    # "SpecificUser" = useful if the user needs special rights
+    Set-ItemProperty -Path "IIS:\AppPools\My Pool 3" -name "processModel.identityType" -value "ApplicationPoolIdentity"
+}
 
 # Assign application pool to website
 Set-ItemProperty -Path "IIS:\Sites\Website1" -name "applicationPool" -value "My Pool 3"