Configure Azure Application Gateway

Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. As an integral component for deploying web applications, Application Gateway offers various layer 7 load balancing capabilities for Azure. When preparing for the AZ-104 Microsoft Azure Administrator exam, understanding how to configure Azure Application Gateway is key. The configurations cover creating the Application Gateway, configuring routing rules, backend pools, health probes, and listeners.

Creating the Application Gateway

Initialize the Basic Settings:

• Subscription: Choose the Azure subscription in which you want to create the Application Gateway.
• Resource Group: Select an existing resource group or create a new one.
• Name: Provide a unique name for the Application Gateway.
• Region: Choose the region where your Application Gateway will be located.

Specify the Virtual Network:

The Application Gateway must be part of a virtual network. You can either select an existing VNet or create a new one. Generally, a dedicated subnet is created just for the Application Gateway.

Choose a Tier and Size:

• Tier: Choose between Standard, Standard_v2, or WAF (Web Application Firewall) depending on your requirements.
• Instance Count: Configure the number of instances based on your workload’s demands.

Set Up the IP Address:

You can assign either a public or a private IP address. Public IPs are used when the application needs to be accessible from the internet, while private IPs are used for internal-only access.

Configuring Backend Pools

Backend pools are the groups of servers that will serve the traffic for the Application Gateway.

Define Backend Pool:

Create a backend pool by assigning it a name and adding backend targets, which can be virtual machines, IP addresses, or fully qualified domain names (FQDNs).

Assign Targets:

Targets can be added to the backend pool that the Application Gateway will route traffic to. These are often your web servers or applications.

Setting Up Listeners

Listeners are essential to determine how the Application Gateway should respond to incoming traffic.

Configure Basic Listener Properties:

• Frontend IP Configuration: Choose the public or private IP created earlier.
• Port: Commonly HTTP (80) or HTTPS (443) is used.
• Protocol: Select the protocol (HTTP or HTTPS). If HTTPS is selected, you must also provide an SSL certificate.

Advanced Listener Configuration:

For multi-site hosting, SNI (Server Name Indication) enables the Application Gateway to host multiple secure websites with a single listener.

Routing Rules Configuration

Routing rules determine the path of the traffic from the listener to the backend pool.

Create a Rule:

Assign a name for the rule and select the listener that it applies to.

Backend Target:

Choose the backend pool that the rule should route the traffic to.

Backend HTTP Settings:

Configure how the Application Gateway communicates with the backend servers. It includes settings like HTTP or HTTPS protocol, cookie-based affinity, and connection draining.

Configuring Health Probes

Health probes are used to monitor the health of the backend servers.

Probe Settings:

• Configure the probe settings by specifying the probe protocol (HTTP or HTTPS), host name, path, and interval at which the probe will ping the backend servers to check their health.

Assign Probes to HTTP Settings:

Once created, assign these probes to the corresponding HTTP settings that are used by the routing rules.

Final Validation and Deployment

After configuring the Application Gateway, validate the settings and perform any necessary configurations and scaling considerations. Then, you can proceed to create the Application Gateway.

Azure Application Gateway also includes an array of advanced features, such as URL-based routing, redirection, session affinity, WebSocket support, and more. These features offer granular control over web application traffic and enhance the user experience.

Monitoring and Management

Post-deployment, monitoring is crucial for maintaining the Application Gateway. Azure provides metrics and logs that should be observed to ensure the Application Gateway operates as intended. In the case of outages or performance issues, the metrics can help identify and resolve problems quickly.

Scaling and Performance

When configuring the Application Gateway, consider the expected load and performance requirements. Azure Application Gateway offers auto-scaling in the Standard_v2 and WAF_v2 tiers, allowing it to scale automatically based on the current traffic load.

In summary, configuring Azure Application Gateway involves setting up frontend IP configurations, backend pools, HTTP settings, listeners, routing rules, and health probes. The system should be constantly monitored and managed to ensure optimal performance and availability. Understanding these steps and effectively implementing them is essential for the AZ-104 Microsoft Azure Administrator exam.