Azure Application Gateway: Overview and Configuration Example

Azure Application Gateway is a Layer 7 (HTTP/HTTPS) load balancer that provides advanced application delivery and load balancing services. It is designed to optimize and secure the delivery of web applications. Here's a detailed overview of Azure Application Gateway along with a configuration example:

Features of Azure Application Gateway:

1. HTTP/HTTPS Load Balancing:

   • Load balances HTTP and HTTPS traffic at the application layer.

2. SSL Termination:

   • Supports SSL termination, allowing the offloading of SSL/TLS decryption from backend servers to the Application Gateway.

3. Web Application Firewall (WAF):

   • Integrates with Azure Web Application Firewall for protection against common web vulnerabilities.

4. Session Affinity:

   • Supports session affinity (sticky sessions) to route client requests to the same backend instance.

5. Rewrite and Redirect Rules:

   • Enables the configuration of rewrite and redirect rules to modify the URL structure.

6. Multi-Site Hosting:

   • Hosts multiple websites on the same Application Gateway.

7. Health Probes:

   • Monitors the health of backend instances using health probes and removes unhealthy instances from the load balancing rotation.

8. URL-Based Routing:

   • Allows URL-based routing to different backend pools based on specific path rules.

9. Azure Monitor Integration:

   • Integrates with Azure Monitor for monitoring and diagnostics.

Configuration Example:

Let's configure an Azure Application Gateway for a sample web application:

1. Login to Azure Portal:

   • Navigate to the Azure Portal.

2. Create an Azure Application Gateway:

   • Click on "Create a resource" and search for "Application Gateway."
   • Click "Create" to start the Azure Application Gateway creation wizard.

3. Configure Application Gateway Settings:

   • Specify details such as subscription, resource group, application gateway name, region, and SKU (Standard or WAF).

4. Configure Frontend IP Configuration:

   • Set up frontend IP configuration, including public or private IP, and port.

5. Configure Backend Pools:

   • Create backend pools and add virtual machines or instances to distribute traffic.

6. Configure HTTP Settings:

   • Specify HTTP settings, including port, protocol, and cookie-based affinity.

7. Configure Health Probe:

   • Set up a health probe to monitor the health of backend instances. Specify the protocol, port, and other settings.

8. Configure Routing Rules:

   • Create routing rules to define how traffic should be routed based on URL path rules.

9. Enable SSL Termination (Optional):

   • If needed, enable SSL termination for offloading SSL/TLS decryption from backend servers to the Application Gateway.

10. Configure Web Application Firewall (Optional):

    • If security is a concern, enable Azure Web Application Firewall and configure WAF settings.

11. Review and Create:

    • Review the configured settings and click "Create" to deploy the Azure Application Gateway.

12. Monitor Application Gateway Performance:

    • Use Azure Monitor or other monitoring tools to track Application Gateway performance, health, and diagnostics.

13. Scale Resources (Optional):

    • Depending on your application's needs, scale resources by adjusting the SKU or adding more backend instances.

14. Clean Up Resources:

    • Once done, clean up resources by deleting the Azure Application Gateway or specific resources as needed.