Azure Application Gateway: Article - 1 of 24 (2024)

Azure Networking 1 of 24 

This content has been created to contribute to anyone who wants to learn Microsoft 365 & Azure. The content is created in English. Turkish and German translations will be completed as soon as possible.

Load Balancer

Load balancer is a device or software application that helps to distribute network or application traffic across multiple servers.

Load balancers work by directing client requests to different servers based on various factors such as server availability, response time, load, and location. They have become an essential component in modern IT infrastructures as they help ensure high availability, scalability, and performance of applications, websites, or databases.

Azure Application Gateway

Azure Application Gateway is a layer 7 load balancer, It allows you to manage traffic to your web applications based on various criteria such as URL path, host header, and HTTP header values. In addition to load balancing, It also supports cookie-based session affinity, which ensures that user sessions are maintained with the same backend server throughout the session, improving performance and reducing the risk of data loss.

Azure Application Gateway can be deployed in either a public or private subnet within a virtual network and can be integrated with other Azure services such as Virtual Machines, Azure Kubernetes Service, and Azure Container Instances, providing a highly scalable and flexible solution for modern cloud applications.

Understanding Layer 7 Load Balancing

Layer 7 load balancing is a type of load balancing that operates at the application layer of the OSI model. It allows you to distribute traffic to different servers based on the content of the HTTP request.

Features

Azure Azure Application Gateway provides the following key features to address modern business needs.

See Also

What is Azure Application Gateway v2?Diving into Azure Load Balancer Types: 2023's Complete GuideAWS WAF vs Cisco WSA | What are the differences?What is a Web Application Firewall?

• SSL/TLS Offloading: By terminating SSL/TLS connections at the gateway, Azure Application Gateway can reduce the load on backend servers, improving performance and scalability.
• Web Application Firewall (WAF): The built-in WAF can protect web applications from common web attacks such as SQL injection and cross-site scripting (XSS), ensuring the security of the applications and the data they store.
• URL Path-Based Routing: With URL Path-Based Routing, traffic can be routed to different backend servers based on the URL path of the request. This can be useful for web applications that have different components or services that need to be accessed separately.
• Session Affinity: By providing session affinity, Azure Application Gateway can direct requests from the same client to the same backend server, ensuring consistency and reducing the risk of errors or data loss.
• Autoscaling: Azure Application Gateway can automatically scale up or down based on the traffic load, ensuring that your web applications are always available and responsive. You can configure the autoscaling rules and thresholds to meet your performance and cost objectives.

Best Practices

By implementing the best practices, you can manage traffic to your web applications more effectively, while ensuring high reliability, scalability, and security.

Use Azure Private Endpoints: Using Azure Private Endpoints is another way to ensure additional security. Azure Private Endpoints allow you to connect to your application gateway and backend servers privately over the Azure backbone network. This provides an additional layer of security and ensures that traffic is not exposed to the public internet.

Implement Health Probes: Health probes are essential for ensuring that the application gateway routes traffic to healthy servers. Health probes allow the application gateway to check the health of the backend servers and detect any issues.

Implement Caching: Implementing caching is another way to significantly improve performance. Caching enables the application gateway to store frequently requested content in cache and serve it to users from cache, reducing the load on the backend servers and improving response times.

Monitor and Analyze Traffic: Monitoring and analyzing traffic is crucial for identifying potential issues and improving performance. Analyzing traffic can help detect issues such as slow load times, high bounce rates, and other performance issues that may prompt adjustments to caching or autoscaling settings to improve performance.

Use Network Security Groups: Using Network Security Groups is another way to control access to your backend servers. Network Security Groups allow you to control inbound and outbound traffic to your backend servers, thereby preventing unauthorized access to your backend servers.

Use HTTPS Listeners: It is essential to use HTTPS listeners to ensure secure traffic flow between the client and the application. HTTP traffic is unencrypted and can be easily intercepted by attackers. This leaves sensitive information, such as credit card details, vulnerable to theft. On the other hand, HTTPS encrypts all traffic between the client and the application, providing an additional layer of security.

Implement SSL Offloading: Implementing SSL offloading is crucial for reducing the load on backend servers and improving performance. SSL offloading allows the application gateway to decrypt SSL traffic and forward it to the backend servers in plain text. By doing so, the application gateway handles the decryption of SSL traffic. This reduces the load on the backend servers and improves the website's response times.

Enable Web Application Firewall (WAF): A Web Application Firewall (WAF) is a powerful tool that helps protect your web application against known vulnerabilities and attacks. An effective WAF can detect and block attacks such as SQL injection, cross-site scripting, and cross-site request forgery, thereby preventing potential data breaches or website downtime.

Implement Autoscaling: Implementing autoscaling is essential for websites that experience spikes in traffic during certain times of the day. Autoscaling allows the application gateway to automatically adjust its capacity based on traffic demand. Additionally, autoscaling can reduce costs by allowing you to pay only for the resources you need.

LAB: Step-by-Step:

Business Scenario

Imagine that you have a web application that receives a lot of traffic, and you want to ensure that the traffic is distributed evenly across multiple servers to prevent downtime and improve performance. You also want to secure your web application with SSL/TLS encryption and ensure that only authorized traffic is allowed.

Prerequisites

Before you start creating an Azure Application Gateway, you need to have the following:

• An Azure account with an active subscription. If you don't have an Azure account, you can create a free account here.
• A virtual network with at least one subnet. If you don't have a virtual network, you can create one by following the instructions here.

Steps to Create an Azure Application Gateway

1. Log in to portal.azure.com and navigate to the Azure portal dashboard.
2. Click on the "+ Create a resource" button and search for "Application Gateway" in the search bar.
3. Select "Application Gateway" from the search results and click on the "Create" button.
4. In the "Basics" tab, enter a name for your application gateway. This can be any name you choose that is unique within your Azure subscription. Next, select your subscription from the dropdown list. If you have multiple subscriptions, make sure to choose the one you want to use for this application gateway. Then, create a new resource group or select an existing one from the dropdown list. A resource group is a logical container for related resources in Azure. Finally, choose the region where you want to deploy your application gateway. This should be the region closest to your backend servers.
5. In the "Instance size" section, choose the appropriate size for your application gateway based on your traffic requirements. You can choose from a range of sizes, from Small to Large, depending on your needs.
6. In the "Settings" tab, configure the following:

• Frontend IP configuration: Choose an IP address or create a new one. This IP address is the public IP address that clients will use to access your web application through the application gateway. You can choose an existing IP address or create a new one if you don't have one already.
• Listener: Configure the protocol, port, and SSL/TLS settings. A listener is a component that listens for incoming traffic on a specific port and protocol. You can configure multiple listeners for your application gateway, depending on your needs. For example, you might configure a listener for HTTP traffic on port 80 and another listener for HTTPS traffic on port 443. You can also enable SSL/TLS encryption for your listeners to secure your traffic.
• Backend pools: Add the IP addresses or DNS names of your backend servers. A backend pool is a collection of backend servers that will receive traffic from the application gateway. You can add multiple backend pools to your application gateway, depending on your needs. For example, you might have a backend pool for your web servers and another backend pool for your database servers.
• HTTP settings: Configure the routing rules and health probes. HTTP settings define how traffic is routed to your backend servers and how health probes are performed to monitor the health of your servers. You can configure multiple HTTP settings for your application gateway, depending on your needs.

7. Click on the "Review + create" button to review your settings and create the application gateway. Make sure to review your settings carefully before creating the application gateway to avoid any mistakes.

8. Wait for the deployment to complete and verify that your application gateway is running correctly. Once the deployment is complete, you can navigate to the "Overview" tab to see the status of your application gateway. You should see that it is running and healthy. You can also test your application gateway by accessing your web application through the public IP address of your application gateway.

Frequently Asked Questions (FAQ):

• Q: How can Azure Application Gateway help me improve my website's performance?

Azure Application Gateway can help you improve your website's performance by optimizing traffic flow, SSL offloading, and caching static content. It can also reduce latency by routing traffic to the closest backend server.

• Q: What are the security benefits of using Azure Application Gateway?

Azure Application Gateway provides security features such as SSL termination, Web Application Firewall (WAF) protection, and bot protection. It also enables you to restrict access to your backend servers by configuring network security groups.

• Q: How can I use Azure Application Gateway to improve my website's availability?

Azure Application Gateway can improve your website's availability by enabling you to configure backend server health probes, automatic failover, and autoscaling. It can also integrate with Azure Traffic Manager for global load balancing.

• Q: Can Azure Application Gateway help me optimize my website's traffic flow?

Yes, Azure Application Gateway can help optimize your website's traffic flow by providing URL-based routing, cookie-based session affinity, and path-based routing. It can also perform SSL offloading and caching static content.

• Q: How does Azure Application Gateway support multi-site hosting for my web applications?

Azure Application Gateway supports multi-site hosting by enabling you to configure multiple backend pools and listeners. You can also specify host headers and path-based routing for each site.

• Q: What are the advantages of using URL-based routing with Azure Application Gateway?

URL-based routing enables you to route traffic to specific backend servers based on the URL path. This can help you optimize traffic flow, improve security, and simplify configuration.

• Q: How can Azure Application Gateway help me achieve better session affinity for my users?

Azure Application Gateway can achieve better session affinity (sticky sessions) by using cookie-based session affinity. This enables requests from the same user to be routed to the same backend server, improving the user experience.

• Q: What is autoscaling, and how can it benefit my web applications?

Autoscaling is the ability to automatically adjust the number of backend servers based on demand. This can help you reduce costs by scaling down during periods of low demand and scale up during peak periods.

• Q: How can I configure Azure Application Gateway to meet the specific needs of my business?

Azure Application Gateway can be configured through the Azure portal, Azure PowerShell, or Azure CLI. You can configure backend pools, listeners, rules, health probes, and SSL policies to meet the specific needs of your business.

• Q: What are the pricing options for Azure Application Gateway, and how can I choose the right plan for my business?

Azure Application Gateway has two pricing options: Basic and Standard. Basic offers basic load balancing, SSL termination, and cookie-based session affinity. Standard includes all the features of Basic, along with URL-based routing, multi-site hosting, and autoscaling. You can choose the right plan based on your business needs and expected traffic volume.