What is Azure Application Gateway: Overview and Use Cases

An Azure Application Gateway is a web traffic load balancer that manages and routes incoming internet traffic to your web applications securely and efficiently. It works at the application layer (HTTP/HTTPS) and offers features like SSL termination, URL-based routing, and web application firewall.

How It Works

Think of Azure Application Gateway as a smart traffic controller for your website. When visitors try to access your site, the gateway decides where to send each request based on rules you set, like directing users to different servers depending on the URL they want.

It works at the application level, which means it understands web traffic details like URLs and headers, not just basic network data. This lets it do things like secure your site with SSL certificates, block harmful traffic, and balance the load so no single server gets overwhelmed.

Imagine a receptionist at a busy office who checks each visitor’s purpose and directs them to the right department. Azure Application Gateway does the same for your web traffic, making sure requests go to the right place safely and efficiently.

Example

This example shows how to create an Azure Application Gateway using Azure CLI. It sets up a basic gateway with a frontend IP, backend pool, and HTTP settings.

bash

az network application-gateway create \
  --name myAppGateway \
  --resource-group myResourceGroup \
  --location eastus \
  --sku Standard_v2 \
  --capacity 2 \
  --frontend-port 80 \
  --http-settings-cookie-based-affinity Disabled \
  --http-settings-port 80 \
  --http-settings-protocol Http \
  --backend-pool-name myBackendPool \
  --backend-pool-ip-addresses 10.0.1.4 10.0.1.5 \
  --vnet-name myVnet \
  --subnet mySubnet

Output

Application Gateway 'myAppGateway' successfully created in resource group 'myResourceGroup'.

When to Use

Use Azure Application Gateway when you need to manage web traffic with advanced routing rules, secure your applications with SSL offloading, or protect them using a web application firewall.

It is ideal for scenarios like hosting multiple websites on the same gateway, directing users to different backend servers based on URL paths, or blocking malicious attacks before they reach your servers.

For example, an online store can use it to route requests for product pages to one set of servers and checkout pages to another, while also protecting against common web threats.

Key Points

• Operates at the application layer (HTTP/HTTPS) for smart traffic management.
• Supports SSL termination to simplify certificate management.
• Offers URL-based routing to direct traffic based on request details.
• Includes a web application firewall to protect against common attacks.
• Scales automatically to handle changing traffic loads.

Key Takeaways

Azure Application Gateway routes and secures web traffic at the application layer.

It supports advanced features like SSL offloading and URL-based routing.

Use it to protect web apps with a built-in web application firewall.

It helps balance load and scale automatically for reliable performance.

Ideal for managing multiple web applications behind a single gateway.