Cloud technology

Cloud is ubiquitous. It is used throughout this book. Cloud is used in this book for hosting all environments, implementation of DevOps practices, and deployment of applications.

Cloud is a relatively new paradigm in infrastructure provisioning, application deployment, and hosting space. The only options prior to the advent of cloud was either self-hosted on on-premises data centers or using services from a hosting service provider. However, cloud is changing the way enterprises look at their strategy in relation to infrastructure and application development, deployment, and hosting. In fact, the change is so enormous that it has found its way into every aspect of an organization's software development processes, tools, and practices.

Cloud computing refers to the practice of deploying applications and services on the Internet with a cloud provider. A cloud provider provides multiple types of services on cloud. They are pided into three categories based on their level of abstraction and degree of control on services. These categories are as follows:

• Infrastructure as a Service (also popularly known as IaaS)
• Platform as a Service (also popularly known as PaaS)
• Software as a Service (also popularly known as SaaS)

These three categories differ based on the level of control a cloud provider exercises compared to the cloud consumer. The services provided by a cloud provider can be pided into layers, with each layer being a specific type of service. As we move higher in the stack of layers, the level of abstraction increases in line with the cloud provider's control over services. In other words, the cloud consumer starts to lose control over services as you move higher in each column:

Figure 1: Cloud Services - IaaS, PaaS, and SaaS

Figure 1 shows the three categories of service available through cloud providers and the layers that are comprised in each service. These layers are stacked vertically on each other and each layer in the stack is colored differently depending on who manages it customer or provider. From Figure 1, it is clear that for IaaS, a cloud provider is responsible for providing, controlling, and managing layers from the network layer up to the virtualization layer. Similarly, for PaaS, a cloud provider controls and manages from the hardware layer up to the runtime layer, while the consumer controls only the application and data layers.

Infrastructure as a Service (IaaS)

As the name suggests, Infrastructure as a Service are infrastructure services provided by a cloud provider. This service includes the physical hardware and its configuration, network hardware and its configuration, storage hardware and its configuration, load balancers, compute, and virtualization. Any layer above virtualization is the responsibility of the consumer. The consumer can decide to use the provided underlying infrastructure in whatever way best suits their requirements. For example, consumers can consume the storage, network, and virtualization to provision virtual machines on top of it. It is then consumer's responsibility to manage and control the virtual machines and the software deployed within it.

Platform as a Service (PaaS)

Platform as a Service enables consumers to deploy their applications and services on the provided platform, consuming the underlying runtime, middleware, and services. The cloud provider provides the services from infrastructure to runtime. The consumers cannot provision virtual machines as they cannot access and control them. Instead, they can only control and manage their applications. This is a comparatively faster method of development and deployment because now the consumer can focus on application development and deployment. Examples of Platform as a Service include Azure Automation, Azure SQL, and Azure App Services.

Software as a Service (SaaS)

Software as a Service provides complete control of the service to the cloud provider. The cloud provider provisions, configures, and manages everything from infrastructure to the application. It includes the provisioning of infrastructure, deployment and configuration of applications, and provides application access to the consumer. The consumer does not control and manage the application, and can use and configure only parts of the application. They control only their data and configuration. Generally, multi-tenant applications used by multiple consumers, such as Office 365 and Visual Studio Team Services, are examples of SaaS.

Advantages of using cloud computing

There are multiple distinct advantages of using cloud computing. The major among them are as follows:

• Cost effective: Cloud computing helps organizations to reduce the cost of storage, networks, and physical infrastructure. It also prevents them from having to buy expensive software licenses. The operational cost of managing these infrastructures also reduces due to lesser effort and manpower requirements.
• Unlimited capacity: Cloud provides unlimited resources to the consumer. This ensures applications will never get throttled due to limited resource availability.
• Elasticity: Cloud computing provides the notion of unlimited capacity and applications deployed on it can scale up or down on an as-needed basis. When demand for the application increases, cloud can be configured to scale up the infrastructure and application by adding additional resources. At the same time, it can scale down unnecessary resources during periods of low demand.
• Pay as you go: Using cloud eliminates capital expenditure and organizations pay only for what they use, thereby providing maximum return on investment. Organizations do not need to build additional infrastructure to host their application for times of peak demand.
• Faster and better: Cloud provides ready-to-use applications and faster provisioning and deployment of environments. Moreover, organizations get better-managed services from their cloud provider with higher service-level agreements.

We will use Azure as our cloud computing provider for the purpose of demonstrating samples and examples. However, you can use any cloud provider that provides complete end-to-end services for DevOps.

We will use multiple features and services provided by Azure across IaaS and PaaS. We will consume Operational Insights and Application Insights to monitor our environment and application, which will help capture relevant telemetry for auditing and monitoring purposes. Azure virtual machines running Windows Containers will be provisioned and they will act as our hosting platform. We will use Windows Server 2016 as the target operating system for our applications. Azure Resource Manager (ARM) and templates, which we will look into in detail in the next chapter, as our choice of framework and deployment automation. We will also use Desired State Configuration and PowerShell for configuration management within virtual machines and containers.

We will use Visual Studio Team Services, a suite of PaaS services on cloud provided by Microsoft, to set up and implement our end-to-end DevOps practices. Microsoft also provides the same services as part of Team Foundation Services (TFS) as an on-premises solution.

Technologies like Pester, DSC, and PowerShell can be deployed and configured to run on any platform. These will help both in the validation of our environment and in the configuration of both application and environment, as part of our configuration management process.

We will introduce a sample application in Chapter 5, Building a Sample Application, and the entire application lifecycle management will be implemented through DevOps practices. Windows Server 2016 is our target platform for deploying the application. Windows Server 2016 is a breakthrough operating system from Microsoft also referred to as Cloud Operating System. We will look into Windows Server 2016 in the following section.