Kubernetes has been the go-to platform for container orchestration, and with its growth, the need for efficient and flexible traffic management has become crucial. Traditionally, the Ingress Controller and Ingress resources have been used to manage traffic routing in Kubernetes clusters. However, a new and more powerful alternative is emerging—the Gateway API.
In this blog post, we will explore the differences between the Gateway API and the traditional Ingress model, highlighting why the Gateway API is quickly becoming the future of Kubernetes traffic management.
Understanding the Basics
Before diving into the comparison, let’s quickly review what each component does:
- Ingress Controller/Ingress Resources: Handles HTTP/HTTPS routing to services inside a Kubernetes cluster. It uses rules to direct traffic based on URL paths or domains.
- Gateway API: A new, extensible API designed to provide more granular control over traffic routing, including support for multiple protocols and advanced configurations.
1. Architecture and Flexibility
- Ingress Controller: Ingress is simpler but limited in flexibility. It relies on fixed configuration fields, which can be challenging when dealing with complex scenarios. Customization often involves using inconsistent annotations that vary by implementation.
+-------------------------------------+
| Client Requests |
| (HTTP/HTTPS Traffic) |
+-------------------------------------+
|
v
+-------------------------------------+
| Ingress Controller |
|-------------------------------------|
| - Interprets Ingress rules |
| - Routes HTTP/HTTPS traffic |
| - Limited role-based separation |
+-------------------------------------+
|
v
+-------------------------------------+
| Kubernetes Services |
| (Backend applications: Web, API, DB)|
+-------------------------------------+
- Ingress Resource: Defines simple HTTP/HTTPS routing rules.
- Ingress Controller: Processes these rules and directs traffic to services accordingly.
- Annotations: Used for customization but vary between implementations, leading to inconsistencies.
- Gateway API: Built with a modular architecture that separates the control and data planes. It uses specific CRDs (Custom Resource Definitions) like Gateway, GatewayClass, HTTPRoute, and more, allowing for advanced and flexible configurations that are easier to manage.
+-------------------------------------+
| Client Requests |
| (HTTP, HTTPS, TCP, UDP Traffic) |
+-------------------------------------+
|
v
+-------------------------------------+
| Gateway |
|-------------------------------------|
| - Acts as the entry point |
| - Supports multiple protocols |
| - Extensible via GatewayClass |
+-------------------------------------+
|
+-------------------------------------+
| HTTPRoute / TCPRoute |
|-------------------------------------|
| - Granular traffic routing rules |
| - Header-based routing, splitting |
| - Weighted traffic management |
+-------------------------------------+
|
v
+-------------------------------------+
| Kubernetes Services |
| (Backend applications: Web, API, DB)|
+-------------------------------------+
- GatewayClass: Defines the infrastructure-level settings, usually managed by infrastructure teams.
- Gateway: Acts as a logical gateway for traffic, handling multiple protocols and forwarding requests to the appropriate route.
- Route Resources (HTTPRoute, TCPRoute, etc.): Handle detailed traffic management, making it easy to define complex routing rules.
- Role-based Separation: Allows different teams to manage different parts of the network configuration, improving collaboration and security.
2. Extensibility and Customization
- Ingress Controller: Extending the functionality depends heavily on vendor-specific annotations, which can lead to inconsistent behavior across different implementations.
- Gateway API: Designed with extensibility in mind, it supports multi-protocol routing (HTTP, TCP, UDP) and advanced traffic management features out of the box. This makes it a better choice for complex use cases.
3. Role-Based Management
- Ingress Controller: Does not provide a clear separation of roles, making it challenging to divide responsibilities between infrastructure and application teams.
- Gateway API: Supports role-based configurations, allowing infrastructure teams to manage GatewayClass and platform/application teams to manage route configurations (HTTPRoute, TCPRoute), fostering better collaboration.
4. Granularity and Traffic Management
- Ingress Controller: Limited to basic HTTP-based routing, making it difficult to implement traffic splitting or advanced routing strategies.
- Gateway API: Provides more granular control over routing and supports advanced traffic management features like weighted traffic routing and canary deployments directly within the API.
5. Stability and Maturity
- Ingress Controller: A mature and widely adopted technology but limited by its simplicity.
- Gateway API: Though newer, it is rapidly gaining support from the Kubernetes community and is being developed with future scalability and extensibility in mind.
6. Portability
- Ingress Controller: Configurations often depend on annotations that vary between different implementations, leading to portability issues.
- Gateway API: Promotes consistency and portability, as its design accommodates vendor-specific features in a structured way that reduces reliance on annotations.
7. Multi-Tenant Support
- Ingress Controller: Basic multi-tenancy support, but lacks fine-grained isolation.
- Gateway API: Supports multi-tenancy with features like Namespace-bound route resources, providing a more secure and isolated environment for different applications or teams.
When to Choose Gateway API Over Ingress Controller ?
You might be wondering which option is better for your Kubernetes setup. Here are some guidelines:
- Choose Ingress Controller if:Your setup requires only basic HTTP/HTTPS routing.You don’t need complex traffic management or role-based separation.
- Choose Gateway API if:You need multi-protocol support and advanced routing features.You are looking for a solution that separates infrastructure and application concerns.You want a future-proof, scalable traffic management solution.
What are the Evolution Timelines ?
- 2015: Ingress API was introduced in Kubernetes 1.1, establishing a basic standard for traffic management.
- 2020: Ingress v1 became stable with Kubernetes 1.19, bringing enhancements to the original Ingress API.
- 2020: Gateway API was introduced in alpha in Kubernetes 1.18 as a response to the need for more flexible and robust traffic management features.
- 2024: The Gateway API is growing in adoption and is expected to become the future standard for Kubernetes traffic management.
Ingress API
- Introduced: The Ingress API was first introduced in Kubernetes 1.1 in 2015.
- Purpose: It was designed to provide a way to manage external access to services running in a Kubernetes cluster, mainly handling HTTP and HTTPS traffic. The goal was to standardize how traffic enters the cluster and is routed to different services.
- Maturity: Ingress has been a core component of Kubernetes for years and reached a more stable state with Ingress v1 in Kubernetes 1.19 in 2020, improving its features and making it generally available.
Gateway API
- Introduced: The Gateway API was introduced later, as a Kubernetes SIG-NETWORK project, starting with its first alpha release in Kubernetes 1.18 in 2020.
- Purpose: The Gateway API was designed to address the limitations of the Ingress API, focusing on a more extensible, role-oriented, and modular way to manage traffic routing for various protocols beyond HTTP/HTTPS (such as TCP and UDP). It aimed to provide a more consistent and flexible model for defining and managing traffic flows.
- Maturity: The Gateway API is still under active development, gradually progressing through alpha and beta stages. As of 2024, it continues to gain wider support from the Kubernetes ecosystem, with more contributors and vendors adopting it for advanced use cases.
Will Gateway API replace Ingress in Future?
The Gateway API was introduced to address the specific limitations of the Ingress API, such as its limited protocol support, lack of extensibility, and inconsistent use of annotations for customization. The Gateway API provides a more structured approach to defining traffic flows and allows for advanced use cases, making it the evolution path for Kubernetes network management.
While the Ingress API remains a widely-used solution, the Gateway API is seen as the long-term direction for Kubernetes traffic management due to its scalability, flexibility, and vendor-agnostic design.
The Gateway API is expected to become the next-generation standard for traffic management in Kubernetes and will likely replace the Ingress API over time. However, this transition will be gradual, and both APIs will coexist for the foreseeable future. Here’s why Gateway API is positioned to replace Ingress and what you can expect:
1. Designed to Address Ingress Limitations
The Gateway API was created to solve specific problems with the Ingress API, including:
- Limited protocol support: Ingress mainly supports HTTP and HTTPS, while the Gateway API supports additional protocols like TCP and UDP.
- Annotation-based customization: The Ingress API relies heavily on vendor-specific annotations, which can lead to inconsistent behavior across different implementations. The Gateway API’s design focuses on extensibility and modularity, making it easier to implement advanced traffic routing without relying on annotations.
- Role-based architecture: The Gateway API provides a clearer separation of concerns between infrastructure and application teams, allowing for more organized management of networking resources.
2. Long-Term Vision for Kubernetes Networking
The Kubernetes community, specifically the SIG-NETWORK group, is guiding the development of the Gateway API with the intention that it will be the future of Kubernetes traffic management. The new API is designed with more powerful capabilities and flexibility that cater to the needs of modern microservices architectures.
3. Adoption by the Ecosystem
- Many Kubernetes networking providers (e.g., Istio, Traefik, NGINX, Envoy) are actively developing support for the Gateway API in their controllers.
- Vendors are aligning their roadmaps with the Gateway API, as its more standardized structure makes it easier to support cross-platform and multi-cluster environments.
4. Coexistence with Ingress for Backward Compatibility
- Ingress API will continue to be supported: The Ingress API will remain available and supported by Kubernetes for the near future, ensuring backward compatibility with existing setups.
- Incremental migration: Organizations with existing Ingress resources don’t need to switch immediately. The Gateway API will allow for an incremental adoption path, letting users transition their traffic management setups at their own pace.
5. Development Status
- The Gateway API is still evolving, with improvements and new features being added as it progresses through alpha, beta, and stable stages.
- Until the Gateway API reaches complete stability and maturity, Kubernetes will continue to support the Ingress API to ensure stability for production environments.
What to Expect in the Future
- Gradual Deprecation of Ingress: Once the Gateway API reaches a mature, stable state and gains widespread adoption, it is likely that the Kubernetes community will deprecate the Ingress API. However, this process will be slow and carefully managed to give organizations plenty of time to migrate.
- Future Enhancements: As the Gateway API continues to develop, it will likely introduce even more advanced features that are not possible with the Ingress API, further encouraging its adoption.
Should You Start Using Gateway API Now?
- For new projects: If you’re starting a new Kubernetes project or setting up a new cluster, it’s a good idea to consider using the Gateway API. It offers more flexibility and will future-proof your traffic management setup.
- For existing projects: If you have an existing deployment using Ingress, there’s no immediate need to migrate, but it’s a good idea to plan for the future. Familiarize your team with the Gateway API and consider transitioning gradually to leverage its advanced capabilities.
Conclusion
The Gateway API is poised to eventually replace the Ingress API as the standard for traffic management in Kubernetes. Its modern design, extensibility, and support for multiple protocols make it a more powerful and flexible solution. However, the transition will be gradual, and the Ingress API will remain supported for the foreseeable future to ensure backward compatibility and a smooth migration path.
Organizations can start adopting the Gateway API to future-proof their Kubernetes setups, knowing that they are aligning with the long-term vision for Kubernetes networking.
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