To begin this book, I thought the best place to start would be with a basic understanding of Microsoft Azure Stack Hub. The idea of this is to look at a question I am asked by customers all the time. What is Microsoft Azure Stack Hub? In simple terms, then, Microsoft Azure Stack Hub is an extension of Microsoft Azure, but this is only part of the answer. Microsoft Azure Stack Hub is a hybrid cloud platform that allows you to use Azure services from your company or a service provider data center. When people think of Microsoft Azure, they think of the public cloud offered by Microsoft, but it is, in fact, a complete ecosystem that incorporates not just the public cloud but also the on-premises versions called Microsoft Azure Stack. This includes Microsoft Azure Stack HCI, which stands for Hyper-Converged Infrastructure. HCI will be explained in detail in Chapter 2, Azure Stack Architecture but for now, it is enough to say that with HCI, both compute and storage are supplied from the same server. This is different from a traditional infrastructure, where storage and compute are separate. Microsoft Azure Stack Edge along with Microsoft Azure Stack Hub and Microsoft Azure Stack HCI conform to this pattern. This book is only focused on Microsoft Azure Stack Hub, but it is worth understanding the complete ecosystem as this will help highlight the differences between the different versions of solutions under the Microsoft Azure Stack banner. This becomes important especially when it comes to running solutions in a hybrid cloud scenario, which we will cover later in this chapter. The advantage of Microsoft Azure Stack is that it provides a consistent environment that those who already use Microsoft Azure will be more than familiar with. In fact, the promise of Microsoft Azure Stack Hub when you talk it through can be thought about in terms of the following concepts:

• Consistent application development
• Azure services available on-premises
• Integrated delivery experience

For a developer who builds cloud applications for Microsoft Azure, they can take all the skills and tools they already use onto this platform. The deployment process that's used for Microsoft Azure is the same one that's used for Microsoft Azure Stack Hub. Development tools such as Visual Studio can also be used within this environment. Microsoft markets the fact that applications that run in Microsoft Azure can be run on Microsoft Azure Stack Hub with no changes other than deployment location, which is not strictly the case as some changes are nearly always required.

Microsoft Azure capabilities are also available within Microsoft Azure Stack Hub, which, again, breeds familiarity both from a developer standpoint but also from an operator and administrator standpoint. The following Microsoft Azure capabilities can be found in Microsoft Azure Stack Hub:

• Virtual machines: Rapid deployment with scaling on demand.
• Containers: Linux and Windows Servers containers, Azure Kubernetes Services.
• Networking: Virtual Network, Load Balancer, VPN Gateway, network security groups, public IPs, route tables.
• Storage: Blobs, tables, and queues.
• Key Vault: Securely protect application keys and secrets.
• Azure App Service: Web and API applications, Azure Functions, serverless computing.
• Azure Marketplace: Ready to go applications from the Azure Marketplace.
• Event Hubs: Scalable event processing for ingesting and processing large amounts of event data.
• Azure IoT Hub: Centralized message hub for communications between IoT applications and devices.

We will be covering each of these capabilities and services in detail later in this book, along with their limitations, as they are integral to creating offers and services from Microsoft Azure Stack Hub.

Supporting the Azure Stack Hub infrastructure

In addition to Microsoft Azure's capabilities and the support offered by Microsoft, Microsoft Azure Stack Hub is also supported by a myriad of both hardware and software vendors. I myself work for Lenovo, who provide certified hardware solutions that can be used to run Microsoft Azure Stack Hub on-premises, and I also work closely with Microsoft to ensure they adhere to the best practices when it comes to deploying Microsoft Azure Stack Hub. Lenovo are by no means the only hardware vendor to offer certified hardware for Microsoft Azure Stack Hub, and it is also supported on offerings from Dell, HPE, and Cisco, among others.

As well as the various hardware solutions that are available in the market, Microsoft Azure Stack Hub is also supported by software vendors extensively. Some industry standard solutions that are available to run in Microsoft Azure are also supported in Microsoft Azure Stack Hub through the Azure Marketplace. This allows customers to run the same software applications, such as Red Hat, F5, Docker, Kubernetes, Chef, and so on, in the same way in both their on-premises environment and the public cloud via Microsoft Azure.

Given the support of Microsoft and their hardware partners, this allows Microsoft Azure Stack Hub to offer a fully integrated delivery experience. Microsoft Azure Stack Hub is fast to deploy, allowing customers to get up and running quickly. The billing model within Microsoft Azure Stack Hub can be extended from Microsoft Azure to allow you to pay for use within the same Microsoft Azure subscription bill.

The key takeaway for Microsoft Azure Stack Hub from this quick overview is that this is an on-premises version of Microsoft Azure that is fully owned and operated by the customer within their own data center. Customers completely control the access, applications, and data that's stored in their Microsoft Azure Stack Hub. They are also responsible for ensuring that any applications or data being provided by Microsoft Azure Stack Hub are available at all times to their customers, regardless of whether they're internal or external. Therefore, I always describe Microsoft Azure Stack Hub as your own private Microsoft Azure region and you as the operator performing the role of Microsoft.

The real power of Microsoft Azure Stack Hub is when it is combined with the public Microsoft Azure Cloud in a truly hybrid manner. Throughout this chapter, I will introduce you some common hybrid use cases that I come across when I am working with customers during their cloud journeys.

Microsoft Azure Stack Hub is really the only consistent hybrid cloud where the tools and processes are consistent. Not only are the tools and processes consistent but so is the underlying infrastructure. As an example, let's take a look at some of these and why they work so well when it comes to running a hybrid cloud environment.

The following diagram tries to illustrate that Azure and Azure Stack Hub are consistent in the way they present their tools and processes:

Figure 1.1 – Consistency of tools and processes

We now have a clearer picture of what Microsoft Azure Stack Hub is and how it is closely related to Azure. To prepare you for the next chapter, we will now dive into how Microsoft Azure Stack Hub is used in disconnected scenarios for private cloud.

Understanding private cloud

Azure Stack Hub can be deployed in two different scenarios, depending on whether connectivity to Azure is required or not. One of the attractions of Azure Stack Hub is that it can be run completely standalone, with no connectivity to the internet. This is particularly useful for organizations that want the capabilities that are offered by the cloud but are unable to make use of public cloud offerings. This may be due to regulatory restrictions on data storage, latency issues with connectivity to public Azure, secure environments with no internet connectivity, environments with limited or unreliable network connectivity, and more.

The other use case is where you have a disconnected instance of Azure Stack Hub running in your data center. This is for organizations that are looking to modernize their applications on-premises and have legacy applications that cannot be moved into the public cloud.

Edge and disconnected solutions

Microsoft Azure Stack Hub can be used for applications where there may be connectivity issues in edge locations with limited network bandwidth. This allows logic and data processing to be performed closer to the users. This also applies to locations where real-time latency may be a consideration. An example of this I have seen was with a customer I have worked with who was capturing telemetry from trains. This can also equally be applied to locations such as oil rigs, cruise ships, or secure government sites.

Azure Stack Hub is not just beneficial as a private cloud but is also a key part of a hybrid cloud. We will look at some of these use cases next.