Cloud computing has become the default option to design, build, and implement Information Technology (IT) applications for businesses across the globe. In the old days, you would host the entire infrastructure, hire a group of developers, and design each component and process required to build your applications. This approach not only ate into the bottom line, but also often did not follow best practices. It also lacked flexibility and scope for innovation.

Understanding cloud computing has become vital for IT professionals worldwide if they are to sustain their jobs and make progress in their careers. You can no longer deliver old-school solutions to your clients—it is simply not cost-effective in today's fast-paced IT world.

In addition, architecting solutions for the cloud comes with its own challenges, such as security considerations and network connectivity. This makes it crucial to upskill so that you can gain a deep understanding of how to build resilient, scalable, and reliable solutions that can be hosted in the cloud.

In this chapter, we introduce you to the concept of cloud computing, what it includes, and the key advantages of moving to the cloud. We also discuss the various cloud computing models, as well as deployment options for the cloud. Understanding the key differences between the models and deployment options and their use cases and benefits is fundamental to formulating an effective cloud-adoption strategy for your business.

We also look at a high-level overview of virtualization—a principal ingredient that has made cloud computing possible.

This chapter covers the following topics:

• What is cloud computing?
• Exploring the basics of virtualization
• Exploring cloud computing models
• Understanding cloud deployment models

Cloud computing is a term used to describe the on-demand access to IT services that comprise compute, network, storage, and software services from third-party suppliers, usually via the public internet or some form of direct wide-area network (WAN) access. Companies can provision necessary IT applications for their organization without having to procure and manage their own infrastructure to host those applications. Instead, they lease/rent the required IT infrastructure from such third-party providers.

Cloud computing has existed for many years in some form, since the invention of the internet. In the old days, Hotmail (first launched in 1996 and now branded as Microsoft Outlook) was a prime example of early cloud computing. You could set up email accounts for your colleagues and yourself on Hotmail and use them to communicate. An alternative would be to host your own email servers' (the infrastructure) network connectivity, as well as the email application (the email software). This would ultimately mean additional costs as well as management overheads to maintain the email servers you hosted.

Today, cloud computing has become mainstream and is, in several cases, the default option for many companies and start-ups. Currently, Amazon Web Services (AWS) is the largest provider of cloud computing services, offering a variety of cloud IT services in the form of infrastructure, platform, and software solutions. You can opt to consume these services rather than creating your own dedicated environment to host your business applications. The sheer size of AWS enables it to actually provide the necessary components to host your business applications at a fraction of the cost, while providing high availability (HA), security, and resilience.

The six advantages of cloud computing

Let's take a look at the six advantages of cloud computing, according to AWS (AWS, Six Advantages of Cloud Computing, https://docs.aws.amazon.com/whitepapers/latest/aws-overview/six-advantages-of-cloud-computing.html), as depicted in the following screenshot:

Figure 1.1 – The six advantages of cloud computing

Tip

The AWS Certified Cloud Practitioner examination assumes that you have these six advantages memorized when testing the Define the AWS Cloud and its value proposition objective.

Let's look at these advantages in detail, as follows:

• Trade capital expense for variable expense: One of the primary benefits of moving to cloud computing instead of hosting your own on-premises infrastructure is the method of paying for that infrastructure. Traditionally, you would have to procure expensive hardware and invest precious business capital to acquire infrastructure components necessary for building an environment to host applications.

  With cloud computing, you pay for the same infrastructure components only as and when you consume them. This on-demand, pay-as-you-go model also means that you save costs when you are not utilizing resources.

  The shift away from capital expense (CAPEX) for variable expense, also known as operating expense (OPEX), means that you can direct your precious business capital to more important areas of investment, such as developing new products or improving your marketing strategy.

• Benefit from massive economies of scale: As an individual business, you would generally have to pay retail rates to purchase necessary IT hardware and build an environment that can be used to host your applications. Cloud providers such as AWS, however, host infrastructure for hundreds of thousands of customers, and even get involved in innovating and having components manufactured to their specifications. This gives even greater economies of scale and allows them to offer lower pay-as-you-go rates to customers.
• Stop guessing capacity: Traditionally, while carrying out capacity planning, you would procure necessary hardware components for future growth. Predicting future growth is extremely difficult, and this often meant that you would overprovision your environment. The result would be expensive idle resources simply going to waste. The fact that you would have made large CAPEX to acquire those components would ultimately be detrimental to the balance sheet due to the rapid loss in value arising from depreciation. On the flip side, some companies may end up underprovisioning capacity to save on costs. This can have an adverse effect on corporate image, if—for example—due to underprovisioned resources your customers are not able to complete transactions or suffer from poor performance.

With cloud computing and sophisticated management software, you can provision the necessary infrastructure when you need it most. Moreover, with monitoring and automation tools offered by cloud vendors such as AWS, you can automatically scale out your infrastructure as demand increases and scale back in when demand falls. Doing so will allow you to pay only for what you consume, when you consume it.

• Increase speed and agility: Cloud vendors such as AWS enable you to launch and configure new IT resources in a few mouse clicks—for example, you can provision a new fleet of servers for your developers within minutes, allowing your organization to exponentially increase its agility in building infrastructure and launching applications. If you are building test and development environments or performing experimental work as part of researching a new product/service, then once those tasks are complete you can just as quickly terminate those environments. Equally, if a particular project is being abandoned midway, you do not need to be worried about having any physical wastage—you just turn off or terminate what you no longer need. By contrast, prior to the invention of virtualization technologies (discussed later), provisioning a new server to host a database would often take weeks. This would include the time it takes to place an order with a supplier for suitable hardware, having it delivered, installing additional components such as storage and memory, and then finally implementing the manual process of installing operating systems and securing them. This process of building data centers also means that you are diverting money away from the main business—precious capital that could be spent on innovating existing products or developing new ones.
• Stop spending money running and maintaining data centers: Hosting your own on-premises infrastructure consumes several hidden costs. In addition to using up precious capital to purchase expensive hardware, you also need a team of engineers to efficiently configure every infrastructure component and lease necessary real estate to rack, stack, and then power up your servers. You would also be required to keep the servers cool with appropriate air-conditioning systems—and that's not all. You would also have to spend money on expensive maintenance contracts to handle the wear and tear of the hardware.

  By hosting your applications on AWS's infrastructure, you no longer need to worry about these hidden costs. Your real-estate costs and utility bills can be dramatically reduced, making your business more competitive.

• Go global in minutes: AWS host their data centers in various regions across the globe. Although you may be based in one country, you will have complete access to all regions. This will help you offer lower latency and a superior customer experience, regardless of where your customers are located. Hosting copies of your resources in additional regions can also help you design for disaster recovery (DR) and business continuity requirements.

By way of contrast, the cost of setting up physical data centers in other countries in which you may not have a presence may be cost-prohibitive and might prevent you from rapid global expansion. Access to multiple regions also enables you to meet any compliance or regulatory requirements related to where data is stored and how it is managed.

In this section, we learned about the basics of cloud computing and discussed its six key advantages. We understood that adopting cloud technologies helps customers manage their costs better, while also enabling them to scale their applications much faster and become more agile. In the next section, we'll discuss one of the most important underlying components of a cloud computing service—virtualization.

Virtualization is one of the core technologies that has enabled cloud computing to go mainstream and has given birth to cloud providers such as AWS, Microsoft Azure, and Google Cloud Platform (GCP), who provide a vast array of services and applications, along with capabilities such as high availability (HA), elasticity, and the ability to provision services for their customers, usually within minutes.

Before the adoption of virtualization, if you wanted to outsource your infrastructure requirements, an IT services provider would have to provision physical infrastructure components such as a physical server for your business and grant access via the internet. Provisioning physical servers, however, often involves long lead times, from sourcing and installing all the hardware components such as the central processing unit (CPU), memory, and storage, to configuring an operating system and any necessary applications. This could mean waiting for days to have your environment configured.

The advancement of hardware technologies such as CPUs, memory, and storage has seen a substantial increase in performance and capability, to the extent that physical servers hosting a single operating system and a few applications often remain idle. Software engineering and the improvements in software design have, by way of contrast, ensured that hardware resources are efficiently consumed to power those applications. The net result has been that physical hardware resources are rarely consumed to their maximum capability by a single operating system and a small set of applications.

This relationship between hardware and software has contributed to the invention of virtualization. Virtualization technologies and hypervisors have made it possible to emulate the physical hardware components of a single physical server as multiple virtual components. These components are then deployed as multiple virtual machines (VMs), each running its own operating system and suite of applications.

A hypervisor is essentially a piece of software that sits between the actual physical hardware and the VMs. It is responsible for enabling the operating systems and applications running on those VMs to access the resources of the physical hardware in a manner that is controlled and that isolates the resources from each other. The hypervisor and its associated management software are used to carve out virtualized representations of the physical hardware components into smaller virtual components, which are then presented as VMs. Each VM can then have its own operating system installed, along with any required applications.

One of the greatest advantages of virtualization is the speed at which resources can be provisioned. With software being used to emulate existing physical hardware (so that the hardware is available when a customer makes a request), the lead times to provision virtual servers, storage, or network environments are drastically reduced.

In the following diagram, we can see how virtualization enables us to allocate virtual storage devices to our individual VMs from the physical storage attached to the server:

Figure 1.2 – Traditional physical architecture versus virtualized architecture

One of the greatest advantages of virtualization is the speed at which resources can be provisioned. Since software is designed to emulate existing physical hardware (to enable the availability of hardware when a customer makes a request), the lead times to provision virtual servers, storage, or network environments is drastically reduced.

Virtualization versus cloud computing

Virtualization, in itself, is not cloud computing. The technology, however, is responsible for making it possible to deliver cloud computing services. One of the primary characteristics of a cloud computing provider is the ability to provision virtualized infrastructure resources using a self-service management tool. AWS offers such tools in the form of its Management Console (accessible via a web browser), command-line interface (CLI), and direct access to its software application programming interfaces (APIs), to enable customers to provision their resources such as servers, network, storage, and databases. By offering well-defined APIs and enabling automation, cloud providers have made it possible for customers to provision necessary resources using a self-service model. Customers do not have to wait in a queue to get their resources deployed while a cloud engineer performs the necessary configuration for them. Customers can interact with the cloud services directly using API calls, and spin up their own resources in a matter of minutes.

Ultimately, cloud computing providers make use of virtualization and modern hardware technologies that are aware of virtualization, as well as software to deliver shared computing resources, Software-as-a-Service (SaaS)-based products, and other on-demand services via the internet. In addition, providers such as AWS offer solutions to enable elasticity, automation, scalability, and HA—all on a pay-as-you-go pricing model, which makes their services accessible to almost any type of client in any location.

In summary, here are the benefits of virtualization:

• Efficient use of powerful hardware by setting up multiple VMs to offer different applications
• Enables server consolidation, which translates to reduced costs
• Allows you to manage large-scale installations and deployments at a faster pace
• Improves security through infrastructure isolation and efficient management of underlying hardware resources
• Enables you to host various operating systems that serve different applications on the same hardware

In this section, we learned that virtualization technology has been a primary driving force in the evolution of cloud computing. The technology enables the provisioning of resources such as servers, networking components, and storage services in a matter of minutes. In addition, virtualization management applications enable us to build self-service platforms. Customers can simply log in to a management console and provision the necessary resources to build an architecture to host their application.

In the next section, we'll explore the cloud computing models available. Different models require varied levels of management and accordingly offer different levels of flexibility.

Cloud computing today offers businesses the ability to offload the cost and complexity of hosting and managing their applications—for example, many providers offer mainstream applications as a complete service that does not require any kind of infrastructure management by the customer. Examples include Microsoft Office 365, which is a suite of desktop productivity applications including email, messaging, and collaboration services offered via the internet. At the same time, many organizations also need to host bespoke line-of-business (LOB) applications such as those developed in-house. Often, this means that they need access to configure the necessary infrastructure in a manner best suited to the needs of the application.

To that end, companies can enlist the services of cloud providers such as AWS, which offers different cloud models to suit the specific needs of the business. The following are three main cloud models offered by most cloud vendors such as AWS.

Infrastructure as a Service

The Infrastructure as a Service (IaaS) model offers the greatest flexibility in giving the customer access and the ability to configure the underlying network, storage, and compute services that power their LOB applications. This model is very similar to owning and managing your own physical infrastructure. However, with cloud computing, a clear difference lies in the fact that you work with virtualized infrastructure components rather than having access to the underlying physical components.

The IaaS cloud computing model is ideal if you need greater control over how your infrastructure components need to be configured (usually from the operating system layer up) to support a given application.

Platform as a Service

Platform as a Service (PaaS) is another cloud computing model designed to remove the burden of configuring and managing underlying infrastructure resources such as compute, storage, and network services. PaaS is designed to allow your organization to focus on developing your application code and offers you a platform to deploy and manage your application releases, updates, and upgrades.

As your developers deploy their application code on the PaaS environment, the provider provisions the infrastructure required to support the application. This will include the necessary network architecture, firewall rules, storage, compute services, operating system management, and runtime environments.

Depending on your vendor, the PaaS model may still offer some degree of flexibility in how the underlying infrastructure is configured. AWS, for example, gives you the option to make necessary modifications to the underlying infrastructure, offering an additional level of flexibility. Example of such services include AWS Elastic Beanstalk, AWS OpsWorks, AWS Lambda, and Amazon Relational Database Service (RDS). While the PaaS model offered by AWS removes the need to minutely configure every infrastructure component (something you would have to do with an IaaS model), it still offers the flexibility of deciding just which components are deployed to support your application.

SaaS

With a SaaS model, the applications are completely hosted and managed by the provider. SaaS services take away any need to set up physical infrastructure to host an application. Instead, you simply connect to those applications via the internet and consume the services offered. A majority of SaaS applications today are fully functional via a standard web browser. This also means that there is no requirement to install any client software.

While the need to set up and configure any infrastructure to host a SaaS application is solely owned and managed by the vendor, many SaaS-based applications still require some form of configuration to meet the specific requirements of your business. You will still need to either have in-house expertise to configure the application to your specification or get support from the provider/third parties. For example, Microsoft Office 365 is a SaaS-based online suite of productivity applications that combines email, file-share, and collaboration services. Although you do not need any physical hardware on premises to host the application since it is accessible as a complete product over the internet, you will have to configure the software elements to meet your business needs. This includes security configurations, configuring your domain name to be associated with the email services offered, or enabling encryption services.

Let's look at some typical examples of IaaS, PaaS, and SaaS models, as follows:

Table 1.1 – Cloud computing models

In this section, we explored cloud computing models. We gained an understanding of the key differences between core models such as IaaS, PaaS, and SaaS. Each model comes with its own set of management overheads and with it, the flexibility to design, build, and deploy your applications.

In the next section, we examine cloud deployment models. Here, we assess the differences between hosting your own on-premises cloud (or private cloud) and using the services of a public cloud provider. We also look at how to connect your private cloud environment with the resources you might host with a public cloud provider.

When it comes to deploying cloud services for your organization, you need to consider which deployment model will suit your business. The decision will be taken based on several factors, such as the industry you are in, compliance and regulatory issues, and also cost management and flexibility of configuration.

There are three primary models of deployment, listed as follows:

• Public cloud
• Private cloud
• Hybrid cloud

These models are represented in the following diagram:

Figure 1.3 – Cloud deployment models

Let's look at each model in a little more detail.

Public cloud

A public cloud is a cloud deployment model in which a business consumes IT services from a third-party vendor, such as AWS, over the internet. This is the most popular model of cloud computing due to the vast array of services on offer. Public cloud providers such as AWS are in the business of delivering IT services across all industry verticals and for businesses of all sizes.

Public cloud services are generally paid for on a pay-as-you-go model and can help your organization move away from a CAPEX of mode of investment in IT to an OPEX mode. This frees up precious capital for more important investment opportunities. Services offered by public cloud vendors will include free services, subscription-based, or on-demand pay-as-you-go, where you are charged based on how much you consume. Providers of public cloud services are also able to offer greater scalability and agility that would otherwise have been too expensive to achieve on your own.

With a public cloud model, customers are offered a self-service capability and access to management consoles and command-line interfaces, as well as having API access to configure and consume the services on offer.

Private cloud

By contrast, a private cloud is a cloud deployment model in which your business procures, installs, configures, and manages all the necessary infrastructure and software components in-house. This may sound very similar to traditional on-premises IT. However, the cloud element of it comes from the fact that additional management software is usually deployed to allow different parts of the business to carry out self-service tasks in provisioning compute, storage, network, and software services from an available catalog of services.

While public cloud providers offer their services to all businesses across the globe and the services are therefore publicly available, a private cloud is designed solely for your business, where you will not be sharing underlying compute resources with anyone external to your organization.

A private cloud is highly customizable to suit the needs of your organization, giving maximum control on key areas such as designing security and infrastructure configuration options. This does not necessarily mean that a private cloud provider (for example, Red Hat OpenStack) is more secure than a public cloud provider. Public cloud providers such as AWS invest vast amounts of money to design security features for the services they offer—features that may be cost-prohibitive if an organization tried to implement them on its own.

Hybrid cloud

This is a combination of IT services deployed both on-premises (and managed solely by your business) and integrated with one or more third-party cloud providers.

Many companies that venture into the public cloud generally start with some form of hybrid model. Often, businesses will move/migrate services to the public cloud to reduce CAPEX investment as they opt for a pay-as-you-go model for the consumption of IT services. An example of this is where companies may need to increase the number of servers deployed for their applications, and rather than procuring more expensive physical hardware, they can set up network connectivity between on-premises infrastructure and the public cloud provider, where they would spin up those additional servers as required. Connectivity options between an on-premises environment and a cloud provider can include setting up a secure Internet Protocol Security (IPsec) virtual private network (VPN) tunnel over the public internet, or even establishing a dedicate fiber-based connection, bypassing the public internet altogether and benefiting from greater bandwidth.

A hybrid cloud is generally also used to help start off your disaster recovery (DR) projects, which often need network communication between the private cloud infrastructure and the services offered by public cloud vendors where the DR solution will be hosted. This enables replication of on-premises data and applications to the DR site, hosted with vendors such as AWS.

Hybrid cloud deployments can also help businesses to start testing out new cutting-edge technologies or adopt a phased migration approach to ensure minimum interruption to normal business functions while the migration is underway. In addition, HA solutions can also be implemented. To cite an example, if the on-premises infrastructure is experiencing downtime, consumers of those services can be redirected to replica services hosted with the public cloud provider.

In this chapter, we explored the basics of cloud computing and how it can help businesses consume necessary IT services to host their applications. We discussed six key advantages of cloud computing and the reasons it offers greater flexibility and resilience, as well as opportunities for innovation and cost reduction.

We also examined three cloud computing models, identifying their key differences and comparing the level of flexibility offered by each model. We also assessed the three cloud deployment models and identified how companies can begin their cloud journey easily by building hybrid cloud solutions.

In the next chapter, we introduce you to AWS. We will discuss its history and provide a brief overview of its services. We will also examine the AWS Global Infrastructure, which gives businesses access to globally dispersed data center facilities within which they can deploy their applications. This will enable businesses to expand their customer reach on a global scale. Then, we will look at the support plans offered by AWS, which are vital to any business looking to consume cloud services.

Here are a few questions to test your knowledge:

1. Which of the following six advantages enables small start-up companies to immediately start consuming IT services from public cloud vendors such as AWS?
   1. Trade capital expense for variable expense
   2. Go global in minutes
   3. Stop guessing capacity
   4. Increase speed and agility
2. Which feature of cloud computing enables customers to deploy their resources in a matter of minutes using a self-service model?
   1. Access to cloud provider APIs
   2. Access to cloud provider engineers to rack and stack servers
   3. Scalability features
   4. Multiple server options
3. What is a hypervisor?
   1. Software that enables you to create and managed virtualized resources running on physical hardware, such as VMs
   2. Software used to monitor the health of your Windows servers
   3. Software used to create HA websites
   4. Hardware that enables you to increase the performance of your physical servers
4. Which of the following are the primary benefits of server virtualization? (Select two answers.)
   1. Efficient use of physical hardware resources
   2. Ability to provision virtual servers in a matter of minutes
   3. Enhanced encryption services
   4. Ability to meet compliance requirements
5. Which of the following is a prime example of IaaS?
   1. A service that gives you access to configure underlying virtual compute, storage, and network resources to host your application
   2. A service that abstracts the underlying infrastructure, allowing you to focus on your application code deployment process
   3. A service that hosts and delivers a complete application via a public network, with no access to any underlying infrastructure
   4. A service that allows you to consume hardware resources for a short lease period and pay on a metered basis
6. Which of the following is a prime example of PaaS?
   1. A platform that hosts and delivers a complete application via a public network, with no access to any underlying infrastructure
   2. A service that gives you access to configure underlying virtual compute, storage, and network resources to host your application
   3. A service that abstracts the underlying infrastructure, allowing you to focus on your application code deployment process
   4. A service that allows you to build infrastructure using code for repeat deployments in different environments
7. Which of the following is a prime example of SaaS?
   1. A service that gives you access to configure underlying virtual compute, storage, and network resources to host your application
   2. A service that abstracts the underlying infrastructure, allowing you to focus on your application code deployment process
   3. A service that hosts and delivers a complete application via a public network, with no access to any underlying infrastructure
   4. A service that allows developers to adopt DevOps strategies for their software development life cycle
8. Which cloud deployment model enables you to connect your on-premises workloads with resources you have deployed with a public cloud provider such as AWS?
   1. Private cloud
   2. Public cloud
   3. Hybrid cloud
   4. Hyper cloud