Solution architecture in the public cloud

Solution architecture in the cloud has become increasingly important these days and is becoming the "new normal" as more enterprises choose to migrate their workload to it. The public cloud has been a critical factor fueling start-up organizations' growth, as they do not need huge upfront investment. It provides flexibility to organizations to be run as an experiment, to be agile and innovative.

The great thing about cloud computing architecture is that you have an end-to-end view of all architecture components, including the frontend platforms, the application development platform, servers, storage, database, automation, delivery, and the networks that are required to manage the entire solution landscape.

Before jumping into solution architecture in the cloud, let's understand more about the public cloud and how it is becoming an essential and driving technology platform for businesses.

What is the public cloud?

The public cloud is based on the standard computing model in which a service provider makes resources, such as virtual machines, applications, and storage, available to their customers over the internet. Public cloud services offer a pay-as-you-go model.

In the cloud computing model, a public cloud vendor provides on-demand availability of IT resources, such as the server, database, network, and storage, which organizations can use with secure web-based interfaces, or through application programs over the internet. In most cases, the customer only pays for the services that they are using for the duration of utilization, which saves costs for them by optimizing IT resources to reduce idle time.

You can think of the public cloud in terms of an electric power supply model, where you switch on the light and pay only for the amount of electricity you use in units. As soon as you switch it off, you are not paying for it. It abstracts you from the complexity of power generation using turbines, resources to maintain the facility, a large infrastructure setup, and you use the entire service in a simplified way.

In addition to cost benefits, major public cloud providers, such as Amazon Web Services (AWS), Google Cloud Platform (GCP), and Microsoft Azure help to bring innovation by extending their technology platform through the cloud. These public cloud providers have mastered the scalability and future-looking architecture with comprehensive machine learning and analytics. With the public cloud, you get access to these cutting-edge technologies and the option of considering them to advance your architecture.

Public clouds, private clouds, and hybrid clouds

Here, you will get a high-level overview of the different types of cloud computing deployment models. You will learn more about the details in Chapter 5, Cloud Migration and Hybrid Cloud Architecture Design.

A private cloud, or on-premises, is registered to a single organization that owns and accesses it. Private clouds act as a replicate or extension of the company's existing data center. Often, a public cloud has a shared tenancy, which means virtual servers from multiple customers share the same physical server; however, they offer dedicated physical servers to customers if the customer wants it for a license or compliance need. A public cloud, such as AWS, Microsoft Azure, or GCP, utilizes massive IT infrastructure that can be accessed over the internet through a pay-as-you-go model.

A third model is the hybrid cloud, used by large enterprises who are moving their workload from on-premises to a cloud, where they still have a legacy application that cannot move to the cloud directly, or maybe they have a licensed application that needs to stay on-premises—or sometimes, due to compliance reasons, they need to secure data on-premises. In such a situation, the hybrid model helps when the enterprise has to maintain a partial environment on-premises and move other applications to the public cloud. Sometimes an organization moves to test and develop the environment to the public cloud and keep production environments on-premises. A hybrid model can vary depending upon the organization's cloud strategy.

As there are multiple public cloud providers in the market, you may start seeing the trends of multi-cloud. Enterprises choose to distribute their workload between different public cloud vendors to get the most out of each cloud technology or provide options to their team depending on their skill set.

The public cloud architecture

A typical definition of the public cloud is that it is a fully virtualized environment, which is accessible both over the internet or through a private network. However, in recent times, public cloud vendors have also started offering an on-premises physical infrastructure for better hybrid cloud adoption. The public cloud provides a multi-tenancy model, where IT infrastructure, such as storage and computational power, are shared between multiple customers; however, they are isolated at the software and logical network levels and do not interfere with each other's workload. In the public cloud, by creating network-level isolation, organizations can have their virtual private cloud, which is equivalent to the logical data center. Looking at organizations' regulatory needs, the public cloud also provides dedicated physical instances, however, those are also accessible over the web, but this is a less common option.

Public cloud storage achieves high durability and availability by creating a redundancy model using multiple data centers and robust data replication. This makes them achieve architecture resiliency and easy scalability. There are three major types of cloud computing models, as shown in Figure 1.4.

Figure 1.4: Types of cloud computing models

In Figure 1.4 you can see a comparison between customer responsibilities in the on-premises environment with the cloud computing service model. In the on-premises environment, the customer has to manage everything, while in the cloud computing model, customers can offload responsibilities to the vendor and focus on their business needs. The following points are high-level details of services that are provided under different cloud computing models:

• Infrastructure as a Service (IaaS): Here, a cloud vendor provides infrastructure resources, such as a compute server, networking components, and data storage space, as managed services. It helps customers to use IT resources without worrying about handling data center overheads, such as heating and cooling, racking and stacking, physical security, and so on.
• Platform as a Service (PaaS): The PaaS model adds a layer of service where the cloud vendor takes care of the resources that are required for your development platform, such as the operating system, software maintenance, and patching, along with infrastructure resources. The PaaS model facilitates your team's focus on writing business logic and handling data by taking care of all of the burdens of platform maintenance for you.
• Software as a Service (SaaS): The SaaS model adds one more layer of abstraction on top of the PaaS and IaaS models, wherein the cloud or software vendor provides ready-to-use software, and you pay for the service. For example, you use email services such as Gmail, Yahoo! Mail, AOL, and so on, where you get your own space for emails as a service, and you don't have to worry about underlying applications or infrastructures.

The fourth emerging model is the Function as a Service (FaaS) model, which is becoming popular in the building of serverless architecture through using services including AWS Lambda. You will learn more details about serverless architecture in Chapter 6, Solution Architecture Design Patterns.

As the public cloud functionality and the cost model are very different, let's learn how to develop a cloud-native approach to architecture design.

Thinking cloud-native architecture

With the increasing adoption of the cloud, cloud-native architecture is an upcoming trend that optimizes system architectures for cloud capabilities. Typical on-premises architecture is normally built for a fixed infrastructure, as adding new IT resources such as servers and computing power adds a considerable amount of time, cost, and effort. However, the cloud is charged based on usage, and provides ease through automation, such as in the scaling of servers up and down, on-demand, without worrying about a long procurement cycle. Cloud-native architecture primarily focuses on achieving on-demand scale, distributed design, and replacing failed components rather than fixing them.

The public cloud is not just about infrastructure, but most public cloud providers offer a broad range of managed services that allow the user to ignore underlying infrastructure and operation maintenance. For example, AWS provides Lambda, a serverless computing platform that can be used to run code without managing the server or runtime environment. Similarly, the Amazon DynamoDB database is highly scalable; tables can be created and data stored without managing a database server. Managed services make it easy to develop scalable applications rapidly.

In cloud-native architecture, you continually create automated operations for recovery, scalability, self-healing, and high availability using the cloud capabilities of continuous integration, deployment, and infrastructure automation. It encourages the continuous optimization of your application in terms of cost and performance, using new cloud capabilities that are released and improved upon every day.

You will learn more details about cloud-native architecture patterns in the next chapter.

Public cloud providers and cloud service offerings

There are several public cloud providers in the IT industry; among them, the key players are AWS, GCP, Microsoft Azure, and Alibaba Cloud. These providers offer an array of services, from computing, storage, networking, databases, and application development, to analytics and machine learning.

Figure 1.5 is a screenshot from the AWS console; you can see the array of services on offer in multiple areas. The highlighted EC2 service, known as Amazon Elastic Compute Cloud, allows you to spin up a virtual machine in minutes in the AWS cloud.

Figure 1.5: AWS console and service offerings

Public cloud vendors provide infrastructure and facilitate an array of services in various areas, such as analytics, machine learning, blockchain, robotics, application development, email, security, monitoring, and alerting. With the public cloud, different technical capabilities become more accessible to the development team, which helps drive innovation and reduce the time to market for the product launch.

Public cloud providers allow global infrastructure to spread across the world, which helps an application to be scaled globally near your user base. To encourage adoption, all cloud services provide a free-tier service, with lots of learning resources, so you can try your hand and develop your knowledge of them.