[Tech Analysis] Kubernetes Ingress API Deprecation and Gateway API Analysis

Last November, Kubernetes announced the deprecation of technical support for Ingress NGINX, recommending Gateway API as an alternative. The existing Ingress had a limitation known as 'Annotation hell,' where implementing complex routing for large-scale services required excessive reliance on Annotations.

Gateway API is a next-generation standard designed to solve this, offering the following key advantages.

• Role-oriented management: Infrastructure administrators can manage the Gateway, while developers can independently manage the HTTPRoute.
• Standardized features: Header manipulation, traffic mirroring, and weight-based distribution (Canary) are supported as standard API features.
• Flexible protocols: In addition to HTTP, gRPC, TCP, UDP routing is intuitively supported.
• Sharing and reuse: A single Gateway can be shared by HTTPRoutes across multiple namespaces.

To operate Gateway API, a Gateway Controller is required. The article covers the installation process using F5's open source Nginx Gateway Fabric. The environment can be set up by first installing the Gateway API CRD, then deploying the controller via Helm.

The actual traffic flow proceeds in the order Client $\rightarrow$ Gateway (Service & Pod) $\rightarrow$ HTTPRoute $\rightarrow$ Service & Pod. Here, the Gateway Controller does not directly participate in the actual service traffic, but instead performs the role of automatically deploying and managing the related Service and Pod according to the Gateway resource.