General design principles - SaaS Lens

This whitepaper contains additional guidance not found in the SaaS Lens of the AWS Well-Architected Tool.

General design principles

The Well-Architected Framework identifies a set of general design principles to facilitate good design in the cloud for SaaS applications:

  • There’s no one-size-fits-all SaaS architecture: The needs of SaaS businesses, the nature of their domain, their compliance requirements, the segments of their market, the nature of their solution—all of these factors have a distinct influence on the architecture of a SaaS environment. Every SaaS architecture should be surrounded with an operational and customer experience that realizes the agility and software as a service tenets that are core to succeeding as a SaaS offering. Regardless of how the system is architected, the system should enable tenants to be onboarded, managed, and operated through a single pane of glass that allows the SaaS organization to achieve the agility and economies of scale that are foundational to building a SaaS business.

  • Decompose each service based on its multi-tenant load and isolation profile: If you’re decomposing your system into services, your decomposition strategy should consider how multi-tenant loads, tenant tiers, and isolation requirements will influence the services that are part of your system. In these scenarios, each service needs to be considered separately. Some services might be able to pool data, for example, while others might need to silo the data they manage based on compliance or noisy neighbor considerations. You might also find that some services will be deployed in a silo model to enable tiering strategies. Premium tenants, for example, might have some services that are available in a silo model as part of the value story of the premium tier.

  • Isolate all tenant resources: The success of a SaaS system relies heavily on a security model that ensures that tenant resources are always protected from any cross-tenant access. A robust SaaS architecture will introduce isolation strategies across all layers of the architecture, providing specific constructs that ensure that any attempt to access a tenant resource is valid for the current tenant context.

  • Design for growth: The move to a SaaS model is often about growth for SaaS organizations. As you define the architectural and operational footprint of your SaaS offering, you must continually be thinking about how your environment will be able to support an accelerating wave of new tenants. SaaS architects must build a highly agile, frictionless environment that can accommodate spikes in tenant onboarding without adding significant operational overhead. The idea here is to allow for growth in your customer base that doesn’t expand the operational or infrastructure footprint of your SaaS environment.

  • Instrument, capture, and analyze tenant metrics: When you put multiple tenants into an environment—especially a shared environment—it can be challenging to have a clear view of how tenants are using your system. SaaS teams need to invest in metrics instrumentation that can surface insights into the features tenants are using, the load they are putting on your system, the bottlenecks they are facing, the cost profile of their activities, and so on. This data is core to analyzing tenant trends that directly impact the business, architectural, and operational health of a SaaS company and inform its strategy.

  • Onboard tenants through a single, automated, repeatable process: SaaS is all about agility. A key piece of this agility story is the tenant onboarding process. A robust SaaS system will include a frictionless, repeatable process for onboarding new tenants to your system. This promotes scale and is core to enabling growth. It also ensures that new customers will have a faster path to value.

  • Plan to support multiple tenant experiences: SaaS markets and customers don’t all fit into a single profile. SaaS companies often need to support a range of tenant profiles that can place different demands on your architecture and operations. As a SaaS provider and architect, it’s essential to model these tenant personas and build a single environment that includes the constructs and mechanisms needed to span a range of tenant experiences without requiring one-off versions of your product. It’s important to identify the value boundaries of your system to enable the business to create tiers of your offering that can reach multiple segments and promote a customer’s advancement through these tiers.

  • Support one-off requirements through global customization: SaaS agility and innovation are achieved by having a single environment that is run by all customers. Being able to update, manage, and operate all customers collectively is foundational to SaaS. The reality is, though, some customers may request customizations. These customizations should be introduced as configuration options that are available to any customer. Keeping these features in the core of the offering enables a SaaS company to support one-off needs without undermining the agility, operational efficiency, and innovation goals of the business.

  • Bind user identity to tenant identity: Every layer of your architecture is likely to need some notion of tenant context to be able to log data, record metrics, access data, and so on. This means that tenant context needs to become a first-class construct that can be resolved and easily accessed by the layers of your application without invoking another service. The authentication and authorization experience of your solution should bind the tenant identity (and potentially other tenant attributes) to the identity of the authenticated user. This will yield a SaaS identity that is passed through all the layers of your system, enabling easy access to tenant context.

  • Align infrastructure consumption with tenant activity: The activity of tenants in a SaaS environment is often unpredictable. Which resources tenants are consuming, how they’re consuming them, and when they are consuming them can vary significantly. The number of tenants in your system can also change regularly. While these factors can present scaling challenges, a robust SaaS architecture will employ policies that limit over-provisioning and align an application’s infrastructure consumption with the real-time trends in tenant activity. This promotes tighter alignment between tenant workloads and the cost profile of your overall SaaS infrastructure.

  • Limit developer awareness of multi-tenant concepts: While tenancy will flow though the layers of your architecture, it should be your goal to limit the degree to which developers have exposure to tenancy. As a rule of thumb, a developer’s experience writing a multi-tenant service should not be all that different from writing a service that has no notion of tenancy. If developers need to introduce tenancy throughout their code, this will make it challenging to manage and enforce compliance with your application’s multi-tenant policies and mechanisms. This means providing libraries and reusable constructs to developers that hide the details of tenancy.

  • SaaS is a business strategy—not a technical implementation: SaaS environments and their underlying technology choices are shaped directly by the agility, innovation, and competitive needs of the business. The emphasis and mindset here centers around the creation of a service experience for customers that focuses on zero downtime, regular updates, and closer connection with customers. This means designing an architectural and operational footprint that can promote continual evolution and rapid response to market demands. A technically solid architecture that doesn’t enable agility, innovation, and operational efficiency will be unlikely to keep pace with the competitive landscape of the market—especially if you’re competing with other SaaS providers.

  • Create tenant-aware operational views: Operations teams are presented with a new set of challenges in a multi-tenant environment. While having a global view of a system’s health and activity remains important in SaaS environments, a robust SaaS operational footprint will also include insights into how specific tenants or tenant tiers are exercising your system. SaaS operations teams should construct dashboards and views that enable them to analyze and profile the activity and load of individual tenants. Being able to view and troubleshoot usage through the lens of individual tenants is essential to building a proactive, efficient multi-tenant operations experience.

  • Measure the cost impact of individual tenants: The business, architects, and operations teams for a SaaS company often need to have a clear picture of how tenants are impacting the cost footprint of a SaaS environment. For example, are tenants in the basic tier imposing higher costs than tenants in the premium tier? Are tenant consumption patterns or features changing the cost profile of your environment? These are among the questions that can best be answered by have a clear view into tenant cost profiles. This is especially important to understand in environments where tenant resources are shared by multiple tenants. Collecting and surfacing this data often provides a SaaS business with valuable insights that can shape the architecture and business model of a SaaS company.