Introduction to Azure Application Gateway
Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. It provides features like Web Application Firewall (WAF), SSL termination, cookie-based session affinity, and URL-based content routing.
Key Features
Global Load Balancing
Distributes incoming traffic across multiple backend servers to ensure high availability and responsiveness.
Web Application Firewall (WAF)
Protects your web applications from common web exploits and vulnerabilities with OWASP rules.
SSL Termination
Offloads SSL/TLS decryption from your web servers, simplifying certificate management and improving performance.
URL-Based Content Routing
Routes requests to different backend pools based on the requested URL path.
Session Affinity
Ensures that requests from the same user session are consistently directed to the same backend server.
Autoscaling
Automatically scales the Application Gateway capacity up or down based on traffic load.
How it Works
Application Gateway operates at Layer 7 (the HTTP layer) of the OSI model. It receives incoming HTTP and HTTPS requests and routes them to the appropriate backend server based on configured rules. It can inspect the content of the request, such as the URL, headers, and session cookies, to make intelligent routing decisions.
Scenario Examples
- Multi-site hosting: Host multiple distinct web applications on the same Application Gateway instance.
- Microservices architecture: Route requests to different microservices based on the URL path.
- PCI DSS compliance: Utilize the WAF capabilities to protect sensitive payment data.
- SSL offloading: Reduce the CPU load on your web servers by handling SSL/TLS encryption/decryption at the gateway.
Getting Started
To deploy an Application Gateway, you typically need to define its configuration, including listeners, backend pools, routing rules, and health probes. Here's a simplified example of creating an Application Gateway using Azure CLI:
az network application-gateway create \
--name MyApplicationGateway \
--resource-group MyResourceGroup \
--location eastus \
--sku Standard_Medium \
--public-ip-address MyAppGatewayPublicIP \
--frontend-port 80 \
--http-settings-cookie-based-affinity Enabled \
--waf-policy /subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/MyResourceGroup/providers/Microsoft.Network/ApplicationGatewayWebApplicationFirewallPolicies/MyWafPolicy
For detailed deployment steps and advanced configurations, please refer to the official Azure Application Gateway documentation.