Azure Documentation

Configuring Azure Application Gateway

This document provides a comprehensive guide to configuring Azure Application Gateway. You'll learn about the various components and settings available to customize its behavior and optimize your application delivery.

Key Configuration Components

Azure Application Gateway offers a rich set of configuration options to manage traffic flow, security, and performance for your web applications. The primary components include:

Frontend IP Configuration

This defines the IP addresses that the Application Gateway will listen on. You can configure it with a public IP address for internet-facing applications or a private IP address for internal applications.

• Public IP Address: Allows external clients to access your application.
• Private IP Address: Enables internal network access.

Listeners

Listeners are the crucial elements that accept incoming traffic. They associate a frontend IP configuration, port, protocol, and host name with a routing rule.

• Port: Typically 80 for HTTP and 443 for HTTPS.
• Protocol: HTTP or HTTPS. For HTTPS, you'll need to configure an SSL certificate.
• Host Name: Allows you to host multiple web applications on a single Application Gateway instance using different host names.
• Multi-site Listeners: Essential for hosting multiple websites or subdomains.

Backend Pools

A backend pool is a collection of virtual machines, virtual machine scale sets, or web apps that will receive traffic from the Application Gateway.

• Target Types: IP address, FQDN, or App Service.
• Health Probes: Used to determine the health of backend servers.

HTTP Settings

HTTP settings define how the Application Gateway forwards requests to the backend pool. This includes settings for cookies, connection draining, and probe configurations.

• Protocol: HTTP or HTTPS.
• Port: The port on which the backend servers listen.
• Cookie-based session affinity: Enables sticky sessions.
• Connection draining: Gracefully removes backend servers from service.
• Request timeout: Sets the timeout for requests to backend servers.

Routing Rules

Routing rules connect a listener to a backend pool and an HTTP setting. They determine where incoming traffic should be directed.

• Basic Rules: Direct traffic from a listener to a single backend pool.
• Path-based Rules: Allow you to route traffic to different backend pools based on the URL path.

Example Configuration Snippet (ARM Template)

Here's a simplified example of how you might define an Application Gateway configuration using an Azure Resource Manager (ARM) template:

            
            {
                "type": "Microsoft.Network/applicationGateways",
                "apiVersion": "2020-11-01",
                "name": "myApplicationGateway",
                "location": "[resourceGroup().location]",
                "properties": {
                    "sku": {
                        "name": "Standard_V2",
                        "tier": "Standard_V2"
                    },
                    "gatewayIPConfigurations": [
                        {
                            "name": "appGatewayIpConfig",
                            "properties": {
                                "subnet": {
                                    "id": "[variables('subnetRef')]"
                                }
                            }
                        }
                    ],
                    "frontendIPConfigurations": [
                        {
                            "name": "appGatewayFrontendIp",
                            "properties": {
                                "publicIPAddress": {
                                    "id": "[variables('publicIpAddressId')]"
                                }
                            }
                        }
                    ],
                    "backendAddressPools": [
                        {
                            "name": "myBackendPool",
                            "properties": {
                                "backendAddresses": [
                                    {
                                        "ipAddress": "10.0.0.4"
                                    },
                                    {
                                        "ipAddress": "10.0.0.5"
                                    }
                                ]
                            }
                        }
                    ],
                    "httpListeners": [
                        {
                            "name": "myHttpListener",
                            "properties": {
                                "frontendIPConfiguration": {
                                    "id": "[resourceId('Microsoft.Network/applicationGateways/frontendIPConfigurations', parameters('applicationGatewayName'), 'appGatewayFrontendIp')]"
                                },
                                "frontendPort": {
                                    "id": "[resourceId('Microsoft.Network/applicationGateways/frontendPorts', parameters('applicationGatewayName'), 'port_80')]"
                                },
                                "protocol": "Http",
                                "hostName": "www.example.com"
                            }
                        }
                    ],
                    "requestRoutingRules": [
                        {
                            "name": "myRequestRoutingRule",
                            "properties": {
                                "ruleType": "Basic",
                                "httpListener": {
                                    "id": "[resourceId('Microsoft.Network/applicationGateways/httpListeners', parameters('applicationGatewayName'), 'myHttpListener')]"
                                },
                                "backendAddressPool": {
                                    "id": "[resourceId('Microsoft.Network/applicationGateways/backendAddressPools', parameters('applicationGatewayName'), 'myBackendPool')]"
                                },
                                "httpSettings": {
                                    "id": "[resourceId('Microsoft.Network/applicationGateways/httpSettings', parameters('applicationGatewayName'), 'myHttpSettings')]"
                                }
                            }
                        }
                    ],
                    "httpSettings": [
                        {
                            "name": "myHttpSettings",
                            "properties": {
                                "protocol": "Http",
                                "port": 80,
                                "cookieBasedAffinity": "Disabled",
                                "requestTimeout": 20
                            }
                        }
                    ]
                }
            }
            
            

Next Steps

Explore detailed guides on specific configurations like SSL termination, Web Application Firewall (WAF), and autoscaling to enhance your Application Gateway deployment.