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Create an application gateway with internal redirection using Azure PowerShell

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You can use Azure PowerShell to configure web traffic redirection when you create an application gateway. In this article, you define a backend pool using a virtual machines scale set. You then configure listeners and rules based on domains that you own to make sure web traffic arrives at the appropriate pool. This article assumes that you own multiple domains and uses examples of www.contoso.com and www.contoso.org.

In this article, you learn how to:

  • Set up the network
  • Create an application gateway
  • Add listeners and redirection rule
  • Create a virtual machine scale set with the backend pool
  • Create a CNAME record in your domain

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

Note

We recommend that you use the Azure Az PowerShell module to interact with Azure. See Install Azure PowerShell to get started. To learn how to migrate to the Az PowerShell module, see Migrate Azure PowerShell from AzureRM to Az.

Azure Cloud Shell

Azure hosts Azure Cloud Shell, an interactive shell environment that you can use through your browser. You can use either Bash or PowerShell with Cloud Shell to work with Azure services. You can use the Cloud Shell preinstalled commands to run the code in this article, without having to install anything on your local environment.

To start Azure Cloud Shell:

Option Example/Link
Select Try It in the upper-right corner of a code or command block. Selecting Try It doesn't automatically copy the code or command to Cloud Shell. Screenshot that shows an example of Try It for Azure Cloud Shell.
Go to https://shell.azure.com, or select the Launch Cloud Shell button to open Cloud Shell in your browser. Button to launch Azure Cloud Shell.
Select the Cloud Shell button on the menu bar at the upper right in the Azure portal. Screenshot that shows the Cloud Shell button in the Azure portal

To use Azure Cloud Shell:

  1. Start Cloud Shell.

  2. Select the Copy button on a code block (or command block) to copy the code or command.

  3. Paste the code or command into the Cloud Shell session by selecting Ctrl+Shift+V on Windows and Linux, or by selecting Cmd+Shift+V on macOS.

  4. Select Enter to run the code or command.

If you choose to install and use the PowerShell locally, this article 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 Login-AzAccount 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 eastus

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
$vnet = New-AzVirtualNetwork `
  -ResourceGroupName myResourceGroupAG `
  -Location eastus `
  -Name myVNet `
  -AddressPrefix 10.0.0.0/16 `
  -Subnet $backendSubnetConfig, $agSubnetConfig
$pip = New-AzPublicIpAddress `
  -ResourceGroupName myResourceGroupAG `
  -Location eastus `
  -Name myAGPublicIPAddress `
  -AllocationMethod Dynamic

Create an application gateway

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]
$gipconfig = New-AzApplicationGatewayIPConfiguration `
  -Name myAGIPConfig `
  -Subnet $subnet
$fipconfig = New-AzApplicationGatewayFrontendIPConfig `
  -Name myAGFrontendIPConfig `
  -PublicIPAddress $pip
$frontendPort = New-AzApplicationGatewayFrontendPort `
  -Name myFrontendPort `
  -Port 80

Create the backend pool and settings

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

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

Create the first listener and rule

A listener is required to enable the application gateway to route traffic appropriately to the backend pool. In this article, you create two listeners for your two domains. In this example, listeners are created for the domains of www.contoso.com and www.contoso.org.

Create the first listener named contosoComListener 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 contosoComRule using New-AzApplicationGatewayRequestRoutingRule.

$contosoComlistener = New-AzApplicationGatewayHttpListener `
  -Name contosoComListener `
  -Protocol Http `
  -FrontendIPConfiguration $fipconfig `
  -FrontendPort $frontendPort `
  -HostName "www.contoso.com"
$frontendRule = New-AzApplicationGatewayRequestRoutingRule `
  -Name contosoComRule `
  -RuleType Basic `
  -HttpListener $contosoComListener `
  -BackendAddressPool $contosoPool `
  -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
$appgw = New-AzApplicationGateway `
  -Name myAppGateway `
  -ResourceGroupName myResourceGroupAG `
  -Location eastus `
  -BackendAddressPools $contosoPool `
  -BackendHttpSettingsCollection $poolSettings `
  -FrontendIpConfigurations $fipconfig `
  -GatewayIpConfigurations $gipconfig `
  -FrontendPorts $frontendPort `
  -HttpListeners $contosoComListener `
  -RequestRoutingRules $frontendRule `
  -Sku $sku

Add the second listener

Add the listener named contosoOrgListener that's needed to redirect traffic using Add-AzApplicationGatewayHttpListener.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway
$frontendPort = Get-AzApplicationGatewayFrontendPort `
  -Name myFrontendPort `
  -ApplicationGateway $appgw
$ipconfig = Get-AzApplicationGatewayFrontendIPConfig `
  -Name myAGFrontendIPConfig `
  -ApplicationGateway $appgw
Add-AzApplicationGatewayHttpListener `
  -ApplicationGateway $appgw `
  -Name contosoOrgListener `
  -Protocol Http `
  -FrontendIPConfiguration $ipconfig `
  -FrontendPort $frontendPort `
  -HostName "www.contoso.org"
Set-AzApplicationGateway -ApplicationGateway $appgw

Add the redirection configuration

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

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway
$contosoComlistener = Get-AzApplicationGatewayHttpListener `
  -Name contosoComListener `
  -ApplicationGateway $appgw
$contosoOrglistener = Get-AzApplicationGatewayHttpListener `
  -Name contosoOrgListener `
  -ApplicationGateway $appgw
Add-AzApplicationGatewayRedirectConfiguration `
  -ApplicationGateway $appgw `
  -Name redirectOrgtoCom `
  -RedirectType Found `
  -TargetListener $contosoComListener `
  -IncludePath $true `
  -IncludeQueryString $true
Set-AzApplicationGateway -ApplicationGateway $appgw

Add the second routing rule

You can then associate the redirection configuration to a new rule named contosoOrgRule using Add-AzApplicationGatewayRequestRoutingRule.

$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway
$contosoOrglistener = Get-AzApplicationGatewayHttpListener `
  -Name contosoOrgListener `
  -ApplicationGateway $appgw
$redirectConfig = Get-AzApplicationGatewayRedirectConfiguration `
  -Name redirectOrgtoCom `
  -ApplicationGateway $appgw   
Add-AzApplicationGatewayRequestRoutingRule `
  -ApplicationGateway $appgw `
  -Name contosoOrgRule `
  -RuleType Basic `
  -HttpListener $contosoOrgListener `
  -RedirectConfiguration $redirectConfig
Set-AzApplicationGateway -ApplicationGateway $appgw

Create a virtual machine scale set

In this example, you create a virtual machine scale set that supports the backend pool that you created. The scale set that you create is named myvmss and 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.

$vnet = Get-AzVirtualNetwork `
  -ResourceGroupName myResourceGroupAG `
  -Name myVNet
$appgw = Get-AzApplicationGateway `
  -ResourceGroupName myResourceGroupAG `
  -Name myAppGateway
$backendPool = Get-AzApplicationGatewayBackendAddressPool `
  -Name contosoPool `
  -ApplicationGateway $appgw
$ipConfig = New-AzVmssIpConfig `
  -Name myVmssIPConfig `
  -SubnetId $vnet.Subnets[1].Id `
  -ApplicationGatewayBackendAddressPoolsId $backendPool.Id
$vmssConfig = New-AzVmssConfig `
  -Location eastus `
  -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 azureuser `
  -AdminPassword "Azure123456!" `
  -ComputerNamePrefix myvmss
Add-AzVmssNetworkInterfaceConfiguration `
  -VirtualMachineScaleSet $vmssConfig `
  -Name myVmssNetConfig `
  -Primary $true `
  -IPConfiguration $ipConfig
New-AzVmss `
  -ResourceGroupName myResourceGroupAG `
  -Name myvmss `
  -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" }
$vmss = Get-AzVmss -ResourceGroupName myResourceGroupAG -VMScaleSetName myvmss
Add-AzVmssExtension -VirtualMachineScaleSet $vmss `
  -Name "customScript" `
  -Publisher "Microsoft.Compute" `
  -Type "CustomScriptExtension" `
  -TypeHandlerVersion 1.8 `
  -Setting $publicSettings
Update-AzVmss `
  -ResourceGroupName myResourceGroupAG `
  -Name myvmss `
  -VirtualMachineScaleSet $vmss

Create CNAME record in your domain

After the application gateway is created with its public IP address, you can get the DNS address and use it to create a CNAME record in your domain. You can use Get-AzPublicIPAddress to get the DNS address of the application gateway. Copy the fqdn value of the DNSSettings and use it as the value of the CNAME record that you create. The use of A-records is not recommended because the VIP may change when the application gateway is restarted.

Get-AzPublicIPAddress -ResourceGroupName myResourceGroupAG -Name myAGPublicIPAddress

Test the application gateway

Enter your domain name into the address bar of your browser. Such as, https://www.contoso.com.

Test contoso site in application gateway

Change the address to your other domain, for example https://www.contoso.org and you should see that the traffic has been redirected back to the listener for www.contoso.com.

Next steps