Create an application gateway with URL path-based redirection using Azure PowerShell

You can use Azure PowerShell to configure URL-based routing rules when you create an application gateway. In this article, you create backend pools using virtual machine scale sets. You then create URL routing rules that make sure web traffic is redirected to the appropriate backend pool.

In this article, you learn how to:

• Set up the network
• Create an application gateway
• Add listeners and routing rules
• Create virtual machine scale sets for backend pools

The following example shows site traffic coming from both ports 8080 and 8081 and being directed to the same backend pools:

If you prefer, you can complete this procedure using Azure CLI.

If you don't have an Azure subscription, create a Trial before you begin.

If you choose to install and use the PowerShell locally, this procedure requires the Azure PowerShell module version 1.0.0 or later. To find the version, run Get-Module -ListAvailable Az . If you need to upgrade, see Install Azure PowerShell module. If you're running PowerShell locally, you also need to run Connect-AzAccount -Environment AzureChinaCloud to create a connection with Azure.

Create a resource group

A resource group is a logical container into which Azure resources are deployed and managed. Create an Azure resource group using New-AzResourceGroup.

New-AzResourceGroup -Name myResourceGroupAG -Location chinanorth2

Create network resources

Create the subnet configurations for myBackendSubnet and myAGSubnet using New-AzVirtualNetworkSubnetConfig. Create the virtual network named myVNet using New-AzVirtualNetwork with the subnet configurations. And finally, create the public IP address named myAGPublicIPAddress using New-AzPublicIpAddress. These resources are used to provide network connectivity to the application gateway and its associated resources.

$backendSubnetConfig = New-AzVirtualNetworkSubnetConfig `
  -Name myBackendSubnet `
  -AddressPrefix 10.0.1.0/24

$agSubnetConfig = New-AzVirtualNetworkSubnetConfig `
  -Name myAGSubnet `
  -AddressPrefix 10.0.2.0/24

New-AzVirtualNetwork `
  -ResourceGroupName myResourceGroupAG `
  -Location chinanorth2 `
  -Name myVNet `
  -AddressPrefix 10.0.0.0/16 `
  -Subnet $backendSubnetConfig, $agSubnetConfig

New-AzPublicIpAddress `
  -ResourceGroupName myResourceGroupAG `
  -Location chinanorth2 `
  -Name myAGPublicIPAddress `
  -AllocationMethod Dynamic

Create an application gateway

In this section, you create resources that support the application gateway, and then finally create it. The resources that you create include:

• IP configurations and frontend port - Associates the subnet that you previously created to the application gateway and assigns a port to use to access it.
• Default pool - All application gateways must have at least one backend pool of servers.
• Default listener and rule - The default listener listens for traffic on the port that was assigned and the default rule sends traffic to the default pool.

Create the IP configurations and frontend port

Associate myAGSubnet that you previously created to the application gateway using New-AzApplicationGatewayIPConfiguration. Assign myAGPublicIPAddress to the application gateway using New-AzApplicationGatewayFrontendIPConfig. And then you can create the HTTP port using New-AzApplicationGatewayFrontendPort.

$vnet = Get-AzVirtualNetwork `
  -ResourceGroupName myResourceGroupAG `
  -Name myVNet

$subnet=$vnet.Subnets[0]

$pip = Get-AzPublicIpAddress `
  -ResourceGroupName myResourceGroupAG `
  -Name myAGPublicIPAddress

$gipconfig = New-AzApplicationGatewayIPConfiguration `
  -Name myAGIPConfig `
  -Subnet $subnet

$fipconfig = New-AzApplicationGatewayFrontendIPConfig `
  -Name myAGFrontendIPConfig `
  -PublicIPAddress $pip

$frontendport = New-AzApplicationGatewayFrontendPort `
  -Name myFrontendPort `
  -Port 80

Create the default pool and settings

Create the default backend pool named appGatewayBackendPool for the application gateway using New-AzApplicationGatewayBackendAddressPool. Configure the settings for the backend pool using New-AzApplicationGatewayBackendHttpSettings.

$defaultPool = New-AzApplicationGatewayBackendAddressPool `
  -Name appGatewayBackendPool

$poolSettings = New-AzApplicationGatewayBackendHttpSettings `
  -Name myPoolSettings `
  -Port 80 `
  -Protocol Http `
  -CookieBasedAffinity Enabled `
  -RequestTimeout 120

Create the default listener and rule

A listener is required to enable the application gateway to route traffic appropriately to a backend pool. In this article, you create multiple listeners. The first basic listener expects traffic at the root URL. The other listeners expect traffic at specific URLs, such as http://52.168.55.24:8080/images/ or http://52.168.55.24:8081/video/.

Create a listener named defaultListener using New-AzApplicationGatewayHttpListener with the frontend configuration and frontend port that you previously created. A rule is required for the listener to know which backend pool to use for incoming traffic. Create a basic rule named rule1 using New-AzApplicationGatewayRequestRoutingRule.

$defaultlistener = New-AzApplicationGatewayHttpListener `
  -Name defaultListener `
  -Protocol Http `
  -FrontendIPConfiguration $fipconfig `
  -FrontendPort $frontendport

$frontendRule = New-AzApplicationGatewayRequestRoutingRule `
  -Name rule1 `
  -RuleType Basic `
  -HttpListener $defaultlistener `
  -BackendAddressPool $defaultPool `
  -BackendHttpSettings $poolSettings

Create the application gateway

Now that you created the necessary supporting resources, specify parameters for the application gateway named myAppGateway using New-AzApplicationGatewaySku, and then create it using New-AzApplicationGateway.

$sku = New-AzApplicationGatewaySku `
  -Name Standard_Medium `
  -Tier Standard `
  -Capacity 2

New-AzApplicationGateway `
  -Name myAppGateway `
  -ResourceGroupName myResourceGroupAG `
  -Location chinanorth2 `
  -BackendAddressPools $defaultPool `
  -BackendHttpSettingsCollection $poolSettings `
  -FrontendIpConfigurations $fipconfig `
  -GatewayIpConfigurations $gipconfig `
  -FrontendPorts $frontendport `
  -HttpListeners $defaultlistener `
  -RequestRoutingRules $frontendRule `
  -Sku $sku

Add backend pools and ports

You can add backend pools to your application gateway by using Add-AzApplicationGatewayBackendAddressPool. In this example, imagesBackendPool and videoBackendPool are created. You add the frontend port for the pools using Add-AzApplicationGatewayFrontendPort. You then submit the changes to the application gateway using Set-AzApplicationGateway.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

Add-AzApplicationGatewayBackendAddressPool `
  -ApplicationGateway $appgw `
  -Name imagesBackendPool

Add-AzApplicationGatewayBackendAddressPool `
  -ApplicationGateway $appgw `
  -Name videoBackendPool

Add-AzApplicationGatewayFrontendPort `
  -ApplicationGateway $appgw `
  -Name bport `
  -Port 8080

Add-AzApplicationGatewayFrontendPort `
  -ApplicationGateway $appgw `
  -Name rport `
  -Port 8081

Set-AzApplicationGateway -ApplicationGateway $appgw

Add listeners and rules

Add listeners

Add the listeners named backendListener and redirectedListener that are needed to route traffic using Add-AzApplicationGatewayHttpListener.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

$backendPort = Get-AzApplicationGatewayFrontendPort `
  -ApplicationGateway $appgw `
  -Name bport

$redirectPort = Get-AzApplicationGatewayFrontendPort `
  -ApplicationGateway $appgw `
  -Name rport

$fipconfig = Get-AzApplicationGatewayFrontendIPConfig `
  -ApplicationGateway $appgw

Add-AzApplicationGatewayHttpListener `
  -ApplicationGateway $appgw `
  -Name backendListener `
  -Protocol Http `
  -FrontendIPConfiguration $fipconfig `
  -FrontendPort $backendPort

Add-AzApplicationGatewayHttpListener `
  -ApplicationGateway $appgw `
  -Name redirectedListener `
  -Protocol Http `
  -FrontendIPConfiguration $fipconfig `
  -FrontendPort $redirectPort

Set-AzApplicationGateway -ApplicationGateway $appgw

Add the default URL path map

URL path maps make sure that specific URLs are routed to specific backend pools. You can create the URL path maps named imagePathRule and videoPathRule using New-AzApplicationGatewayPathRuleConfig and Add-AzApplicationGatewayUrlPathMapConfig.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

$poolSettings = Get-AzApplicationGatewayBackendHttpSettings `
  -ApplicationGateway $appgw `
  -Name myPoolSettings

$imagePool = Get-AzApplicationGatewayBackendAddressPool `
  -ApplicationGateway $appgw `
  -Name imagesBackendPool

$videoPool = Get-AzApplicationGatewayBackendAddressPool `
  -ApplicationGateway $appgw `
  -Name videoBackendPool

$defaultPool = Get-AzApplicationGatewayBackendAddressPool `
  -ApplicationGateway $appgw `
  -Name appGatewayBackendPool

$imagePathRule = New-AzApplicationGatewayPathRuleConfig `
  -Name imagePathRule `
  -Paths "/images/*" `
  -BackendAddressPool $imagePool `
  -BackendHttpSettings $poolSettings

$videoPathRule = New-AzApplicationGatewayPathRuleConfig `
  -Name videoPathRule `
  -Paths "/video/*" `
  -BackendAddressPool $videoPool `
  -BackendHttpSettings $poolSettings

Add-AzApplicationGatewayUrlPathMapConfig `
  -ApplicationGateway $appgw `
  -Name urlpathmap `
  -PathRules $imagePathRule, $videoPathRule `
  -DefaultBackendAddressPool $defaultPool `
  -DefaultBackendHttpSettings $poolSettings

Set-AzApplicationGateway -ApplicationGateway $appgw

Add redirection configuration

You can configure redirection for the listener using Add-AzApplicationGatewayRedirectConfiguration.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

$backendListener = Get-AzApplicationGatewayHttpListener `
  -ApplicationGateway $appgw `
  -Name backendListener

$redirectConfig = Add-AzApplicationGatewayRedirectConfiguration `
  -ApplicationGateway $appgw `
  -Name redirectConfig `
  -RedirectType Found `
  -TargetListener $backendListener `
  -IncludePath $true `
  -IncludeQueryString $true

Set-AzApplicationGateway -ApplicationGateway $appgw

Add the redirection URL path map

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

$poolSettings = Get-AzApplicationGatewayBackendHttpSettings `
  -ApplicationGateway $appgw `
  -Name myPoolSettings

$defaultPool = Get-AzApplicationGatewayBackendAddressPool `
  -ApplicationGateway $appgw `
  -Name appGatewayBackendPool

$redirectConfig = Get-AzApplicationGatewayRedirectConfiguration `
  -ApplicationGateway $appgw `
  -Name redirectConfig

$redirectPathRule = New-AzApplicationGatewayPathRuleConfig `
  -Name redirectPathRule `
  -Paths "/images/*" `
  -RedirectConfiguration $redirectConfig

Add-AzApplicationGatewayUrlPathMapConfig `
  -ApplicationGateway $appgw `
  -Name redirectpathmap `
  -PathRules $redirectPathRule `
  -DefaultBackendAddressPool $defaultPool `
  -DefaultBackendHttpSettings $poolSettings

Set-AzApplicationGateway -ApplicationGateway $appgw

Add routing rules

The routing rules associate the URL maps with the listeners that you created. You can add the rules named defaultRule and redirectedRule using Add-AzApplicationGatewayRequestRoutingRule.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

$backendlistener = Get-AzApplicationGatewayHttpListener `
  -ApplicationGateway $appgw `
  -Name backendListener

$redirectlistener = Get-AzApplicationGatewayHttpListener `
  -ApplicationGateway $appgw `
  -Name redirectedListener

$urlPathMap = Get-AzApplicationGatewayUrlPathMapConfig `
  -ApplicationGateway $appgw `
  -Name urlpathmap

$redirectPathMap = Get-AzApplicationGatewayUrlPathMapConfig `
  -ApplicationGateway $appgw `
  -Name redirectpathmap

Add-AzApplicationGatewayRequestRoutingRule `
  -ApplicationGateway $appgw `
  -Name defaultRule `
  -RuleType PathBasedRouting `
  -HttpListener $backendlistener `
  -UrlPathMap $urlPathMap

Add-AzApplicationGatewayRequestRoutingRule `
  -ApplicationGateway $appgw `
  -Name redirectedRule `
  -RuleType PathBasedRouting `
  -HttpListener $redirectlistener `
  -UrlPathMap $redirectPathMap

Set-AzApplicationGateway -ApplicationGateway $appgw

Create virtual machine scale sets

In this example, you create three virtual machine scale sets that support the three backend pools that you created. The scale sets that you create are named myvmss1, myvmss2, and myvmss3. Each scale set contains two virtual machine instances on which you install IIS. You assign the scale set to the backend pool when you configure the IP settings.

Replace <username> and <password> with your own values before you run the script.

$vnet = Get-AzVirtualNetwork `
  -ResourceGroupName myResourceGroupAG `
  -Name myVNet

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway

$backendPool = Get-AzApplicationGatewayBackendAddressPool `
  -Name appGatewayBackendPool `
  -ApplicationGateway $appgw

$imagesPool = Get-AzApplicationGatewayBackendAddressPool `
  -Name imagesBackendPool `
  -ApplicationGateway $appgw

$videoPool = Get-AzApplicationGatewayBackendAddressPool `
  -Name videoBackendPool `
  -ApplicationGateway $appgw

for ($i=1; $i -le 3; $i++)
{
  if ($i -eq 1)
  {
     $poolId = $backendPool.Id
  }
  if ($i -eq 2) 
  {
    $poolId = $imagesPool.Id
  }
  if ($i -eq 3)
  {
    $poolId = $videoPool.Id
  }

  $ipConfig = New-AzVmssIpConfig `
    -Name myVmssIPConfig$i `
    -SubnetId $vnet.Subnets[1].Id `
    -ApplicationGatewayBackendAddressPoolsId $poolId

  $vmssConfig = New-AzVmssConfig `
    -Location chinanorth2 `
    -SkuCapacity 2 `
    -SkuName Standard_DS2 `
    -UpgradePolicyMode Automatic

  Set-AzVmssStorageProfile $vmssConfig `
    -ImageReferencePublisher MicrosoftWindowsServer `
    -ImageReferenceOffer WindowsServer `
    -ImageReferenceSku 2016-Datacenter `
    -ImageReferenceVersion latest `
    -OsDiskCreateOption FromImage

  Set-AzVmssOsProfile $vmssConfig `
    -AdminUsername <username> `
    -AdminPassword "<password>" `
    -ComputerNamePrefix myvmss$i

  Add-AzVmssNetworkInterfaceConfiguration `
    -VirtualMachineScaleSet $vmssConfig `
    -Name myVmssNetConfig$i `
    -Primary $true `
    -IPConfiguration $ipConfig

  New-AzVmss `
    -ResourceGroupName myResourceGroupAG `
    -Name myvmss$i `
    -VirtualMachineScaleSet $vmssConfig
}

Install IIS

$publicSettings = @{ "fileUris" = (,"https://raw.githubusercontent.com/Azure/azure-docs-powershell-samples/master/application-gateway/iis/appgatewayurl.ps1"); 
  "commandToExecute" = "powershell -ExecutionPolicy Unrestricted -File appgatewayurl.ps1" }

for ($i=1; $i -le 3; $i++)
{
  $vmss = Get-AzVmss -ResourceGroupName myResourceGroupAG -VMScaleSetName myvmss$i

  Add-AzVmssExtension -VirtualMachineScaleSet $vmss `
    -Name "customScript" `
    -Publisher "Microsoft.Compute" `
    -Type "CustomScriptExtension" `
    -TypeHandlerVersion 1.8 `
    -Setting $publicSettings

  Update-AzVmss `
    -ResourceGroupName myResourceGroupAG `
    -Name myvmss$i `
    -VirtualMachineScaleSet $vmss
}

Test the application gateway

You can use Get-AzPublicIPAddress to get the public IP address of the application gateway. Copy the public IP address, and then paste it into the address bar of your browser. Such as, http://52.168.55.24, http://52.168.55.24:8080/images/test.htm, http://52.168.55.24:8080/video/test.htm, or http://52.168.55.24:8081/images/test.htm.

Get-AzPublicIPAddress -ResourceGroupName myResourceGroupAG -Name myAGPublicIPAddress

Change the URL to http://<ip-address>:8080/images/test.htm, substituting your IP address for <ip-address>, and you should see something like the following example:

Change the URL to http://<ip-address>:8080/video/test.htm, substituting your IP address for <ip-address>, and you should see something like the following example:

Now, change the URL to http://<ip-address>:8081/images/test.htm, substituting your IP address for <ip-address>, and you should see traffic redirected back to the images backend pool at http://<ip-address>:8080/images.

Clean up resources

When no longer needed, remove the resource group, application gateway, and all related resources using Remove-AzResourceGroup.

Remove-AzResourceGroup -Name myResourceGroupAG

Next steps