Testing the application gateway – Configuring Load Balancing

Testing the application gateway

Now that your application gateway is configured, it is ready to test. To do this, perform the following steps:

1. Paste the frontend public IP address from the previous part into your web browser. You should expect to see a web page of sorts; this will validate your connection.
2. Navigate back to your web application and click on Overview in the left pane.
3. Click Stop at the top of the page:

Figure 16.27 – Web app – Stop

4. Note that when you navigate to the public IP of your application gateway, you get an error message as expected.
5. Wait about 5 minutes and navigate back to your Application Gateway service and click on Backend Health under the Monitoring context.
6. Note how you get an unhealthy message indicating an issue on the backend:

Figure 16.28 – Application Gateway – unhealthy backend

7.   Do not delete your resources, as these will be used in the next exercise.

Now that you have experienced deploying Azure Application Gateway and have seen the merits it brings to regional load balancing for services, as well as how to troubleshoot when issues occur, you should now feel comfortable working with application gateways. Next, we will explore how Azure Front Door works in the same space but at a global level.

Azure Front Door

Azure Front Door is a load balancing service that also operates as a Layer 7 load balancer much like Azure Application Gateway. The service is very similar except that it is designed for global delivery of services as opposed to regional. The service also has the ability to enable WAF services and is designed for web-based workloads. One of the great benefits of the Front Door service is its ability to offer different traffic-routing methods:

• Latency: This isdesigned for faster connections to your services by routing requests to the backends that have the lowest latency. This means that services located closer to where you are connecting from globally will be faster and, therefore, respond quicker.

• Priority: You can assume a primary delivery backend pool for your service with a backup (secondary) backend pool when the primary pool fails.

• Weighted: This optionis for when you have several backend pools and want to distribute traffic in a weighted fashion by assigning requests to backend pools in a ratio type proportion.

• Session affinity: This iswhere the user of your service is required to connect to the same server.

Front Door offers several features (many similar to Application Gateway), such as the following:

• URL path-based routing

• Multiple website hosting

• Session affinity

• SSL offloading

• Health probes

• Custom domains

• WAF

• URL Redirect

• URL Rewrite

• IPv6 connectivity

• HTTP/2 Protocol

You now know how to deploy regional load balancing services in Azure. You also know and understand how Azure Front Door works at a global level for load balancing services. You should feel comfortable at this point with the concept of load balancing and understanding the various services available in Azure to serve this purpose. The next skill you will need to learn is how to troubleshoot these services, which we will explore in the next chapter.

Summary

In this chapter, we covered various load balancing services available to us on the Azure platform and how they bring HA to our workloads, both regionally and globally. We also explored how services such as Azure Application Gateway and Front Door enhance these services by analyzing application layer requests to split requests across service areas and resources. In the next chapter, we will explore monitoring and troubleshooting for networks in Azure in more detail.