API gateways are essential for managing and securing data flow between services. As software architectures evolve, different types of API gateways have emerged to address specific challenges: Legacy, Agnostic, and Kubernetes-native. Drawing on insights from Cindy Mullins and Gartner's "Lightweight Gateways" concept, this guide explores these categories to help you understand their strengths and limitations, enabling you to choose the best gateway for your organisation’s needs.
The Role of Legacy API Gateways
Legacy API Gateways were born in an era dominated by monolithic applications, where stability and comprehensive feature sets were paramount. These gateways were designed to integrate seamlessly with traditional on-premises architectures, offering robust solutions for security, traffic management, and API monetisation within a unified platform.
For large-scale enterprises, these gateways provided the reliability and stability needed to manage APIs in controlled environments. They include extensive features such as security enforcement, rate limiting, authentication, load balancing, and detailed analytics, all tailored to a time when software deployments were more static.
However, the very nature of these gateways—monolithic and heavyweight—has become a drawback in today’s fast-paced, dynamic environments. Modern software architectures demand flexibility, scalability, and the ability to integrate seamlessly with cloud-native and distributed systems. Legacy gateways often struggle to meet these demands due to their reliance on proprietary technologies, which can lead to vendor lock-in, and their lack of support for modern development practices like DevOps and continuous integration/continuous deployment (CI/CD) pipelines.
Despite these challenges, legacy API gateways still play a crucial role in many organisations, particularly those with significant investments in traditional IT infrastructure. They are often deeply embedded in existing systems, providing essential support for legacy applications that have yet to transition to cloud-native architectures. In such scenarios, the stability and comprehensive feature set of legacy gateways can be a valuable asset. However, as organisations increasingly adopt cloud-native and microservices-based approaches, the limitations of legacy gateways become more apparent, especially when it comes to handling the dynamic, scalable nature of modern applications.
The Flexibility of Agnostic API Gateways
As businesses began to diversify their technology stacks and adopt multi-cloud strategies, the need for more adaptable API gateways became clear. Agnostic API Gateways emerged as a response to this need, offering a platform-neutral solution that can operate seamlessly across a variety of environments. Unlike legacy gateways, which are often tightly coupled to specific infrastructures, agnostic gateways are designed to function independently of the underlying platform. This flexibility makes them particularly appealing to organisations that require a unified API management solution across diverse and dynamic ecosystems.
The defining characteristic of agnostic API gateways is their emphasis on interoperability and standards-based design. This allows them to integrate with various tools, platforms, and services without the need for significant customisation or reliance on proprietary technologies. As a result, agnostic gateways are well-suited to environments where avoiding vendor lock-in is a priority.
Agnostic gateways are typically lightweight and cloud-native, designed with scalability and flexibility in mind. They can be deployed with minimal overhead, making them ideal for businesses that need to rapidly adapt to changing requirements. Their modular architecture allows for easy integration with existing systems, enabling organisations to extend their API management capabilities without the need for a complete overhaul.
One of the major advantages of agnostic gateways is their support for modern development practices, such as DevOps and CI/CD. By being infrastructure-neutral, these gateways can be seamlessly integrated into CI/CD pipelines, allowing for automated testing, deployment, and scaling of APIs across different environments. This capability is crucial for organisations that prioritise speed and agility in their development processes.
Security is another area where agnostic gateways excel. They are designed to be compatible with various security standards and protocols, enabling organisations to enforce consistent security policies across different environments. Whether an API is deployed on-premises or in the cloud, an agnostic gateway ensures that security measures such as authentication, authorisation, and data encryption are consistently applied.
However, this broad compatibility and flexibility can sometimes introduce complexity, particularly when integrating with legacy systems or protocols. Additionally, because agnostic gateways are designed to be platform-neutral, they may lack some of the deep, specialised features that are available in gateways tailored to specific environments. Organisations must carefully assess their specific requirements and weigh the trade-offs between flexibility and specialisation when choosing an agnostic API gateway.
The Power of Kubernetes-native API Gateways
As cloud-native and microservices architectures became the norm, a new breed of API gateways emerged—those that are Kubernetes-native. These gateways are designed specifically to handle the dynamic, distributed nature of microservices, with deep integration into Kubernetes, the leading container orchestration platform.
Kubernetes-native API Gateways are optimised for managing APIs in environments where agility, scalability, and security are paramount. Unlike traditional or agnostic gateways that function independently of the underlying infrastructure, Kubernetes-native gateways are built to work within the Kubernetes ecosystem. This tight integration allows them to leverage Kubernetes features such as service discovery, scaling, and network policies directly, providing a more cohesive and efficient approach to API management.
One of the standout features of Kubernetes-native gateways is their ability to manage the complex interdependencies within microservices architectures. In Kubernetes, applications are often composed of numerous small, loosely coupled services that can be scaled, updated, or replaced independently. Kubernetes-native gateways are designed to manage these microservices efficiently, ensuring that traffic is routed correctly, security policies are applied consistently, and services remain highly available even as they scale or are updated.
These gateways also shine in supporting modern development practices like DevOps and CI/CD. Because they are native to the Kubernetes environment, they can be tightly integrated into CI/CD pipelines, enabling automated and consistent API management across the entire development lifecycle. This means that as new microservices are deployed or updated, the gateway can automatically adjust routing, apply security policies, and update API documentation, ensuring that the API layer remains consistent and up-to-date without requiring manual intervention.
Security is another area where Kubernetes-native gateways excel. Given the distributed and dynamic nature of microservices, securing APIs in a Kubernetes environment requires a different approach compared to traditional monolithic applications. Kubernetes-native gateways can enforce security policies at the service level, providing fine-grained control over access, authentication, and encryption. They can also integrate with Kubernetes' built-in security features, such as network policies and secrets management, to protect APIs from common threats like unauthorised access and data breaches.
Scalability is a fundamental strength of Kubernetes-native API gateways. Kubernetes itself is designed to scale applications horizontally, allowing additional instances of a service to be created as demand increases. Kubernetes-native gateways scale alongside the services they manage, distributing traffic across multiple instances and preventing any single point of failure. This scalability is crucial for organisations that need to handle fluctuating workloads and ensure high availability, even under heavy traffic conditions.
However, the deep integration with Kubernetes also means that organisations need a certain level of expertise in Kubernetes to fully leverage these gateways. While they are ideal for managing APIs in containerised environments, they may not be the best fit for organisations that still rely heavily on legacy systems or non-containerised applications. In such cases, a hybrid approach that combines Kubernetes-native gateways with other types of gateways may be necessary to achieve comprehensive API management.
Comparing the Three Categories
The decision to use a Legacy, Agnostic, or Kubernetes-native API Gateway depends largely on an organisation’s specific needs and existing infrastructure. Each type offers distinct advantages and poses unique challenges.
Legacy API gateways have long been the cornerstone of API management in traditional, monolithic architectures. Their feature-rich, comprehensive solutions make them well-suited for managing APIs in stable, controlled environments. However, their monolithic architecture can become a limitation in today’s fast-paced, distributed, and cloud-native world. These gateways often require significant infrastructure and can struggle to scale effectively in dynamic environments. Additionally, they are prone to vendor lock-in due to their reliance on proprietary technologies, which can limit flexibility as organisations look to adopt new platforms and technologies.
Agnostic API gateways offer a more flexible and adaptable approach. These gateways are platform-neutral, meaning they can operate across a wide range of environments, from on-premises data centres to multiple cloud platforms. This flexibility makes them ideal for organisations with diverse infrastructure or those looking to avoid vendor lock-in. Agnostic gateways are typically lightweight, modular, and scalable, aligning well with modern, agile development practices. However, the very flexibility that defines agnostic gateways can sometimes introduce complexity, particularly in environments where there is a need to integrate with legacy systems or other specialised platforms. While they are versatile, they may lack the deep, specialised features that more tailored gateways can provide.
Kubernetes-native API gateways represent the cutting edge of API management, specifically designed for cloud-native environments and microservices architectures. These gateways are deeply integrated with Kubernetes, the leading container orchestration platform, and are optimised for managing APIs in dynamic, distributed environments. Their seamless integration with Kubernetes allows them to leverage native features such as service discovery, scaling, and network policies, providing a highly efficient and cohesive approach to API management. Kubernetes-native gateways are particularly well-suited to environments where agility, scalability, and security are paramount. They support modern development practices, such as continuous integration and continuous deployment (CI/CD), and can automatically adjust to changes in the microservices landscape, ensuring consistent and secure API management even as services evolve. However, the deep integration with Kubernetes means that these gateways require a certain level of expertise in Kubernetes to fully leverage their capabilities. Additionally, they may not be the best fit for organisations that rely heavily on legacy or non-containerised applications, where a more traditional or hybrid approach might be needed.
API Gateways and API Federation
As organisations increasingly adopt multi-cloud strategies and microservices architectures, the concept of API Federation has gained prominence. API Federation involves orchestrating and managing APIs across multiple gateways, environments, and regions, effectively creating a unified API layer that abstracts the complexities of underlying services. This approach allows organizations to present a consistent API experience to consumers, regardless of where the APIs are hosted or how they are managed.
The choice of API gateway is fundamental to the success of API Federation, as different types of gateways offer varying levels of support for distributed and federated architectures. The ability of a gateway to integrate with other gateways, manage traffic across multiple environments, and enforce consistent security and governance policies is crucial for maintaining the integrity and performance of the federated API ecosystem.
Legacy API gateways, while robust and feature-rich, often present challenges in the context of API Federation. These gateways are typically designed for centralised, monolithic environments, where APIs are managed within a single, controlled infrastructure. As a result, they may lack the flexibility needed to operate seamlessly across distributed environments. When integrated into a federated architecture, legacy gateways can become bottlenecks, both in terms of performance and in the ability to scale across multiple regions or cloud providers. Additionally, the proprietary nature of many legacy gateways can lead to difficulties in achieving interoperability with other gateways or in adapting to the diverse requirements of a federated system.
Agnostic API gateways are much better suited to API Federation. These gateways are designed to be platform-neutral, enabling them to operate across a wide range of environments, from on-premises data centres to public and private clouds. This flexibility makes them ideal for federated architectures, where APIs need to be managed consistently across different platforms and regions. Agnostic gateways can easily integrate with other API management tools and gateways, regardless of the underlying infrastructure, making it easier to create a cohesive and unified API strategy that spans multiple environments.
Kubernetes-native API gateways offer yet another perspective on API Federation, particularly in cloud-native and microservices-heavy environments. These gateways are deeply integrated with Kubernetes, which has become the de facto standard for container orchestration in modern cloud environments. In a federated API architecture, Kubernetes-native gateways excel at managing APIs within and across Kubernetes clusters, providing a consistent and scalable approach to API management in dynamic, containerised environments.
Because Kubernetes-native gateways are built to work seamlessly within the Kubernetes ecosystem, they can easily federate APIs across multiple Kubernetes clusters, whether they are running in different regions, cloud providers, or even in hybrid setups that include on-premises and cloud-based clusters. This capability is particularly important for organisations that have fully embraced microservices and are looking to scale their applications across distributed environments. Kubernetes-native gateways can manage the complexities of service discovery, load balancing, and traffic routing within a federated architecture, ensuring that APIs remain performant and resilient even as they are scaled across multiple clusters.
However, while Kubernetes-native gateways are highly effective in cloud-native environments, they may not be the best fit for organisations that still rely heavily on legacy systems or that operate in environments where Kubernetes is not the primary orchestration tool. In such cases, a hybrid approach that combines Kubernetes-native gateways with agnostic or legacy gateways might be necessary to achieve a comprehensive API Federation strategy.
Categorised solutions
After all the theory, let's put the above into practice. To do this, we will categorise some of the solutions available for API gateways into three categories.
| API Gateway Solution | Legacy | Agnostic | Kubernetes-native |
|---|---|---|---|
| Ambassador EdgeStack | X | ||
| Apigee | X | ||
| APISIX | X | X | |
| AWS Gateway | X | ||
| Axway | X | ||
| Azure API Management | X | ||
| Boomi | X | ||
| Emissary Ingress | X | ||
| Envoy | X | X | |
| Gloo Edge | X | ||
| Gravitee | X | X | |
| KrakenD | X | ||
| Kong | X | X | |
| MuleSoft | X | ||
| nginx | X | X | |
| SAP API Management | X | ||
| Spring Cloud Gateway | X | X | |
| Traefik | X | ||
| Tyk | X | ||
| Zuplo | X |
Conclusion
The choice of API gateway—whether Legacy, Agnostic, or Kubernetes-native—is crucial for effective API Federation. Legacy gateways offer stability but may struggle in distributed environments. Agnostic gateways provide flexibility across platforms, while Kubernetes-native gateways excel in cloud-native settings. Understanding these strengths and limitations helps organisations build a robust, scalable API strategy that meets the demands of modern, distributed architectures.
References
How to Choose the Right API Gateway for Kubernetes Applications
Charge your APIs Volume 22: Mastering the Art of API Federation
Is API Management Really Dead? Understanding the Role of APIOps
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Daniel Kocot
Senior Solution Architect / Head of API Consulting
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