Understanding and Implementing Azure Internal Load Balancer

An internal load balancer is a crucial component of Azure's infrastructure, allowing you to distribute traffic across multiple instances of a resource within a virtual network.

It's essentially a software-based load balancer that sits inside your virtual network, routing traffic to the most available instance of a resource.

This is particularly useful for applications that require high availability and scalability, such as web servers, databases, and APIs.

By implementing an internal load balancer, you can improve the performance and reliability of your applications, ensuring they're always accessible to users.

To configure an internal load balancer in Azure, you need to specify a valid IP address that resides in the same virtual network as your AKS cluster. The IP address can't already be assigned to another resource in the virtual network.

You can use the az network vnet subnet list Azure CLI command or the Get-AzVirtualNetworkSubnetConfig PowerShell cmdlet to get the subnets in your virtual network. To use a specific IP address, you have two options: set service annotations or add the LoadBalancerIP property to the load balancer YAML manifest.

Here are the steps to set service annotations: Set the service.beta.kubernetes.io/azure-load-balancer-ipv4 annotation for an IPv4 address or service.beta.kubernetes.io/azure-load-balancer-ipv6 for an IPv6 address.Specify the IP address you want to use in the annotation, like this: service.beta.kubernetes.io/azure-load-balancer-ipv4: 10.240.0.25

Alternatively, you can add the LoadBalancerIP property to the load balancer YAML manifest, but this option is deprecating following upstream Kubernetes.

To specify an IP address for your load balancer, you need to make sure it's in the same virtual network as your AKS cluster and not already assigned to another resource.

You can use the Azure CLI command `az network vnet subnet list` or the PowerShell cmdlet `Get-AzVirtualNetworkSubnetConfig` to get the subnets in your virtual network.

There are two ways to specify an IP address with the load balancer: setting service annotations or adding the LoadBalancerIP property to the load balancer YAML manifest.

Here are the two options:

To view the service details and verify that the IP address is correct, use the `kubectl get service` command.

Here's an example of what the output should look like:

```

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE

internal-app LoadBalancer 10.0.184.168 10.240.0.25 80:30225/TCP 4m

```

Note that the IP address in the EXTERNAL-IP column should reflect the specified IP address.

To connect Azure Private Link, you need Kubernetes version 1.22.x or later. You'll also need an existing resource group with a VNet and subnet, which is where you'll create the private endpoint.

Make sure you have these resources in place before proceeding, as you can't create them later. If you don't have a VNet and subnet, you can create one by following the instructions in the Create a virtual network and subnet section.

To connect Azure Private Link to an internal load balancer, you'll need to specify advanced networking settings when creating your AKS cluster. This allows you to deploy the cluster into an existing Azure virtual network and subnets.

To view the cluster identity used by the AKS cluster, you can use the az aks show command. This is necessary to assign the Network Contributor role to the cluster identity.

The Network Contributor role is required to connect the load balancer to your private virtual network and subnet. You can assign this role using the az role assignment create command, specifying the identity-resource-id and virtual-network-resource-id.

Here are the permissions required to define a custom role instead:

These permissions are necessary to join the subnet to the virtual network and read the subnet configuration.

Azure internal load balancer offers a range of scenarios and use cases that can help you host virtual machines in Azure efficiently.

Azure ILB provides load balancing between virtual machines that reside inside a cloud service or a virtual network with a regional scope. This allows for load balancing within a cloud service, from virtual machines to a set of virtual machines that reside within the same cloud service.

ILB enables load balancing within a virtual network, from virtual machines in the virtual network to a set of virtual machines that reside within the same cloud service of the virtual network. It also supports cross-premises virtual networks, from on-premises computers to a set of virtual machines that reside within the same cloud service of the virtual network.

Here are some specific use cases where ILB can be beneficial:

Azure Internal Load Balancing (ILB) offers a range of scenarios for load balancing, including within a cloud service or virtual network with a regional scope.

ILB enables load balancing between virtual machines that reside within the same cloud service or virtual network, providing a new type of load balancing capability.

You can use ILB in various configurations, such as within a cloud service, virtual network, or cross-premises virtual network.

ILB provides load balancing between virtual machines in a cloud service, virtual network, or on-premises computers, enabling new capabilities for hosting virtual machines in Azure.

Here are some specific scenarios where ILB can be used:

ILB can also be used for hosting Internet-facing, multi-tier applications where the back-end tiers are not Internet-facing but require load balancing for traffic from the Internet-facing tier.

This includes load balancing for line-of-business (LOB) applications hosted in Azure without requiring additional load balancer hardware or software.

Including on-premises servers in the set of computers whose traffic is load balanced is another scenario where ILB can be used.

ILB enables you to include on-premises servers in the set of computers whose traffic is load balanced, making it a flexible solution for load balancing.

Internet Facing Multi-Tier Apps can be complex, but let's break it down. The web tier has Internet facing endpoints for Internet clients and is part of a load-balanced set.

A load balancer distributes incoming traffic from web clients for TCP port 443 (HTTPS) to the web servers. This ensures that no single server is overwhelmed with traffic.

The database servers are behind an ILB endpoint, which the web servers use for storage. This setup load balances traffic across the database servers in the ILB set.

Cloud services using the same virtual network will have access to the ILB endpoint. This makes it easier to manage and secure the application.

In some cases, the ILB is deployed to a different cloud service than the one consuming the service for the ILB. This is possible, but it requires careful planning and configuration.

Front-end web servers can be in a different cloud service from the database back-end and still leverage the ILB endpoint within the same virtual network.

To troubleshoot issues with your Azure Internal Load Balancer, you should first check if the load balancer is correctly configured. This involves verifying that you've attached the necessary VMs and configured the traffic rule, health probe, and idle TCP timeout settings.

If you've already created an internal Azure Load Balancer, attached 2 VMs to it, configured the load balancer traffic rule, health probe, and tested the load balancer, then you can move on to the next steps.

Here are the next steps you can take:

Testing the load balancer is a crucial step in ensuring it's working as expected. You can test it by connecting to the lb-TestVM and verifying the webpage.

First, find the load balancer in the Azure portal by searching for it in the search box at the top. Once you've found it, make a note of the private IP address, which can be found on the Overview page.

To access the lb-TestVM, search for Virtual machines in the portal and select it. Then, click Connect and Bastion to access the virtual machine.

Once you're logged in, open Microsoft Edge and enter the private IP address of the load balancer into the address bar. This should display a custom page showing one of the backend server names.

To see the load balancer distribute traffic across both VMs, navigate to the VM shown in the browser message and stop the VM. Then, refresh the browser window to see the load balancer sending traffic to the remaining VM.

Now that you've set up your Azure Load Balancer, it's time to take it to the next level. To get started, you'll want to configure an Internal load balancer to ensure your application is running smoothly.

To configure the load balancer distribution mode, you'll need to consider the type of traffic your application will be handling. This will help you determine the best distribution mode for your needs.

Next, you'll want to configure the idle TCP timeout settings for your load balancer. This will help prevent connections from timing out and ensure your application remains stable.

If you've already created an internal Azure Load Balancer, attached 2 VMs to the load balancer, configured the load balancer traffic rule, health probe, and tested the load balancer, you're already ahead of the game.

Here are the key next steps to keep in mind:

Azure Load Balancer is a powerful tool that helps distribute incoming network traffic across multiple targets. This means that if you have multiple servers, Azure Load Balancer can spread the traffic across them, ensuring that no single server gets overwhelmed.

By using Azure Load Balancer, you can route traffic based on the source IP address and port to a destination IP address and port. This level of control is useful for managing complex network traffic patterns.

One of the key components of Azure Load Balancer is Frontend IP Configurations, which allow you to manage IP addresses and ports.

Azure is a powerful cloud platform that allows you to distribute incoming network traffic across multiple targets.

This is particularly useful for applications that require high availability and scalability. By using Azure Load Balancer, you can ensure that your application is always accessible and responsive to user requests.

Azure Load Balancer allows you to route traffic based on source IP address and port to a destination IP address and port.

This flexibility makes it easy to manage complex network configurations and ensure that your application is always performing optimally.

Here are some key features of Azure Load Balancer:

With Azure Load Balancer, you can create a highly available and scalable application that meets the needs of your users.

Azure Pricing is a crucial aspect to consider when using Azure services. You're charged based on the number of outbound rules, which is a key factor in determining your bill.

Azure Load Balancer Pricing is specifically designed to be cost-effective. You're billed for the first five rules of load balancing, which means you can start small and scale up as needed.

The pricing model is transparent, with no hidden fees. You're not charged for the NAT rules, which is a significant cost savings.

Here's a breakdown of the Azure Load Balancer Pricing:

Azure ILB is a type of load balancer that distributes incoming network traffic across multiple targets in a private network.

You can deploy an internal load balancer in an AKS cluster, and it's created in the same resource group as your AKS cluster, but it's connected to your private virtual network and subnet.

The cluster identity used by the AKS cluster must have the Network Contributor role on the virtual network resource, which can be viewed using the az aks show command.

To assign the Network Contributor role, you can use the az role assignment create command, or define a custom role with the necessary permissions, such as Microsoft.Network/virtualNetworks/subnets/join/action and Microsoft.Network/virtualNetworks/subnets/read.

A backend pool is a group of VMs or instances in a VM scale set serving the incoming request, and you can determine the health status of backend pool instances with health probes.

Azure Monitor is used to check the metrics, alerts, and resource health of Azure Load Balancer, and the SLA guarantees that two or more healthy VMS will always be available.

Here are the key differences between the Basic and Standard Load Balancer:

The Standard Load Balancer also offers features like health probes, HA ports, and secure by default, which are not available in the Basic Load Balancer.