Why Single Sign-on Architecture Is an Ideal Solution for Microservices

Microservices architecture—often called microservices—is a modern application design model developers use for designing large software projects. This architecture enables you to separate an extensive application into many independent parts, with each piece responsible for performing a single function or operation. Then, when a user requests a service, the application calls each of the relevant microservice components. 

For example, if the user of an e-commerce website wants to purchase a product, the app will only interact with the components responsible for processing transactions. Features like user reviews, product searches, and support communication are independent. Of course, all this occurs behind the scenes while the user interacts with a single interface.

A microservices-based approach offers countless benefits, including increased development speed, enhanced application security, rapid and efficient scaling, and improved fault isolation. However, compartmentalizing software in this fashion can also introduce complexities, especially regarding authentication across several disparate services.

The communication among components in microservices requires complex access rules and authorization, especially when using cloud services to house any of these components. The need to authenticate these processes dramatically increases an application’s attack surface, with each segment of intra-service traffic remaining vulnerable to interception by external threat actors.

Traditional monolithic applications feature a unified design where interprocess communications occur within a single executable. As a result, you can access all of an application's functionality using only one process. 

By contrast, a microservice application’s communications among distributed components happen through a local network—or the Internet when connecting to cloud services. This effectively multiplies the complexity of authentication and authorization logic, as microservices must leverage internal APIs to handle data relays among their components. Instead of authenticating once to a monolithic application, microservices must ensure proper permissions at various stages.

Best Practices for Handling Security and Authentication in Microservices

Managing security in microservices-based applications is complex. Unlike monolithic applications with a single entry point, microservices applications might have hundreds of entry points that introduce many areas of vulnerability to the system. However, there are several security recommendations you can follow to ensure the security of your microservices and minimize their susceptibility to threats:

• Develop a custom authorization protocol or use a readily available solution (for example, OAuth) to handle your application’s access control and authorization of its various services.

   

• Use an existing encryption library to secure your application. Unless you have sufficient reason, avoid developing custom code libraries. There are numerous open-source libraries for implementing encryption routines, and they support virtually every major programming language.

   

• Document all libraries and the versions that your application uses. Often, developers of microservices applications use several libraries to create a single service. Some of these libraries may depend on external, third-party libraries. This can expose your application to hundreds of libraries from multiple vendors—of which many you might be unaware. Such a chain of dependencies opens your system to numerous vulnerabilities. Therefore, documenting your application’s libraries provides a crucial reference point. 

   

• Secure all microservices architecture communication with TLS.

   

• Ensure that all microservices components, dependent libraries, and APIs remain up-to-date.

Microservices Versus a Monolith: Which Is Best?

Dr. Peter Rogers coined the term “micro web services” during a cloud computing conference in 2004. Then, until 2011, the term “microservices” rose to prominence to describe the type of software architecture companies like Netflix and Amazon used to design complex applications.

More recently, many businesses have begun shifting their development teams efforts to adopt this approach for developing complex software. This is because the complexity of the code used in monolithic applications makes them too difficult to scale, maintain, and upgrade. In contrast, engineers can work on each component in a microservices app independently, isolating potential issues from the rest of the application and ensuring that it functions even when problems occur.

Furthermore, using a single programming language in monolithic applications makes them incompatible with newer technologies. In contrast, microservices applications can contain—and are compatible with—several languages, making new integrations and changes a relatively seamless process.

Single sign-on (SSO) enables an entity—whether a user, system, process, service, or app—to log in to one service, application, or system and automatically gain access to other applications without needing to sign in again. For example, when users log in to their Gmail account, they are also logged in to all other Google services, including YouTube, AdSense, and Google Drive.

Many organizations have increasingly turned to SSO because it provides a seamless experience for users accessing multiple applications and services. This is especially true for working in cloud environments, as users only need one credential to access all related apps and systems.

In a microservices architecture, you can integrate SSO into any of the following:

• Authenticating users when accessing the microservice application

• Authenticating a microservice component when communicating with other components on the app

• Authenticating external applications when trying to access the microservice application

Handling authentication and authorization in a microservice architecture presents a continual challenge. Each component in the microservices app needs an authentication code to handle the authentication and authorization process. Using the same code in all microservices is a security risk because a single vulnerability in the authentication code will then compromise all components sharing that code. To add to the complexity, specific microservices within the architecture may use a different programming language or web framework to function. 

Fortunately, applying SSO to a microservices architecture can enable all microservice components, users, and external applications to authenticate once and gain access to the full array of services within the app.

Using single sign-on architecture in microservices applications mitigates many complexities associated with the traditional authentication logic implemented in monolithic applications. With SSO, a user can provide one credential to access a suite of available services, while external parties can use APIs to access specific parts of your application.

Using SSO in microservices is the best option to protect your microservices and mitigate many challenges and security issues associated with using a different credential to access each microservice.