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Load Balancer In Azure

In this article, we will discuss load balancers in Azure.

Purpose

Consider an example, where we have a virtual machine hosting a web application. When the number of users increases, the load on the virtual machine also increases. That leads to performance degradation.

This is when the load balancer service comes into the picture. A load balancer is a component added to the virtual network to make sure that the load is distributed across multiple virtual machines.

Components Of Load Balancer

Backend pool → It is the pool of virtual machines. The load balancer distributes the load on the virtual machines present in the backend pool
Frontend IP → An IP address assigned to the load balancer. All requests will hit the frontend IP address and further, the load balancer distributes the load on the virtual machines in the backend pool
Health probe → Checks the health of the virtual machine at regular intervals. If the virtual machine is not well, then the load balancer will not distribute the load on that virtual machine
Load Balancing Rule → A set of rules applied to the specific components of the load balancer

Basic Vs Standard Load Balancer

The below table explains the difference

Load balancer category	Virtual machines	Availability Sets	Scale Sets
Basic load balancer	Single virtual machine	Yes	Yes
Standard load balancer	Multiple virtual machines	Yes	Yes

Internal Vs External Load Balancer

Picture showing the representation of internal and external load balancer

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Consider an example, where the users are sending requests to the load balancer. The load balancer distributes the request to the application backend pool. As the request is coming from an external user. So, the first load balancer is an external load balancer.

The next load balancer internally distributes the load to the database backend pool. So, the second load balancer is the internal load balancer.

Steps Of Creating The Load Balancer

For creating the load balancer, we will work on the following steps: -

Creation of a virtual machine
Creation of the public IP address
Create a load balancer with the public IP address
Setting different components of the load balancer
Configure the backend pool
Configure the health probe
Configure the load-balancing rules
Test the load balancer

Let us work on each step.

Creation Of A Virtual Machine

First, create 2 virtual machines with the following properties: -

Availability options are Availability set

Picture showing selecting the Availability Sets while creating the virtual machine

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Public IP is set to None

Picture showing disabling the public IP address while creating the virtual machine

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Here is the list of 2 virtual machines.

Picture showing the list of virtual machines for the load balancer

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Creation Of The Public IP Address

The next step is to create a public IP address.

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Create A Load Balancer With The Public IP Address

To add the load balancer, click on the + Add button on the load balancer screen.

Picture showing a screen for adding the load balancer

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A screen will appear to create the load balancer. Enter the details.

Picture showing the create load balancer screen

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Scroll down to select the public IP address.

Picture showing the load balancer screen for associating the public IP address with the load balancer

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Complete the process to create the load balancer.

Configure The Backend Pool

Inside the load balancer, click on the Backend pools submenu. Click on the + Add button.

Picture showing a screen for adding the backend pool inside the load balancer

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A screen will appear to enter the details and add the virtual machines.

Picture showing the create backend pool screen inside the load balancer

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Configure The Health Probe

Inside the load balancer, click on the Health probes submenu. To create the health probe, click on the + Add button.

Picture showing a screen for adding the health probe inside the load balancer

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Enter the details and click on the Add button.

Picture showing the create health probe screen inside the load balancer

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Here, the attribute Interval means checking the virtual machine after every 5 seconds to check the health of the virtual machines.

The other attribute Unhealthy threshold means marking the virtual machine as unwell after 2 consecutive failures.

Configure The Load Balancing Rules

Inside the load balancer, click on the Load balancing rules submenu. For adding the rule, click on the + Add button.

Picture showing a screen for adding the load balancing rule inside the load balancer

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Enter the details and click on the Add button.

Picture showing the create load balancing rule screen inside the load balancer

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Test The Load Balancer

Now, check the URL. You can see that load is distributed to virtual machine 1 and virtual machine 2.

Picture showing the default of virtual machine 1

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Picture showing the default of virtual machine 2

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Posted By -	Karan Gupta

Posted On -	Saturday, May 8, 2021

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