Introduction

When exposing services to external traffic in Kubernetes, two common approaches are Kubernetes Ingress and Istio Ingress Gateway. Both provide a way to route traffic into a cluster, but they differ in architecture, features, and use cases. This article explores their differences and when to use Istio’s ingress gateways.

What is Kubernetes Ingress?

Kubernetes Ingress is a native API object that manages external HTTP/S traffic to services within a Kubernetes cluster. It uses an Ingress Controller to handle routing rules and direct requests to backend services.

Features of Kubernetes Ingress:

• Basic Traffic Routing: Directs HTTP/S traffic based on hostnames and paths.

• TLS Termination: Supports SSL/TLS encryption.

• Load Balancing: Distributes traffic among service pods.

• Annotations & Custom Configs: Allows configuration of timeouts, rewrites, and security policies.

Limitations of Kubernetes Ingress:

• Lacks advanced traffic control like retries, fault injection, and circuit breaking.

• Limited observability and tracing for monitoring requests.

• No built-in mutual TLS (mTLS) support.

• Does not support advanced service mesh features like request mirroring or traffic shifting.

What is Istio Ingress Gateway?

Istio Ingress Gateway is a component of the Istio service mesh that manages external traffic into an Istio-enabled cluster. Unlike Kubernetes Ingress, Istio’s ingress is integrated with Envoy Proxy, providing fine-grained traffic control, security, and observability.

Features of Istio Ingress Gateway:

• Advanced Traffic Management: Supports traffic splitting, canary deployments, and header-based routing.

• Security Features: Built-in mTLS, authentication, and JWT authorization.

• Observability: Provides detailed metrics, logs, and tracing.

• Protocol Support: Handles not only HTTP/S but also TCP, gRPC, and WebSockets.

• Dynamic Configuration: Uses Istio’s control plane for flexible routing policies.

Example Istio Ingress Gateway Configuration:

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: my-ingress-gateway
  namespace: istio-system
spec:
  selector:
    istio: ingressgateway
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "example.com"

This configuration defines an Istio Gateway that listens for traffic on port 80 and routes it to services based on Istio’s VirtualServices.

Kubernetes Ingress vs. Istio Ingress Gateway

When to Use Kubernetes Ingress vs. Istio Ingress Gateway

Use Kubernetes Ingress if:

• You need basic HTTP/S traffic routing.

• You want to use a lightweight ingress without a service mesh.

• You are not using advanced security or traffic control features.

Use Istio Ingress Gateway if:

• You need fine-grained traffic control (e.g., A/B testing, request mirroring).

• You require mTLS, JWT authentication, or advanced security policies.

• You need observability with full tracing and detailed logs.

• You are running a service mesh with Istio.

Conclusion

Both Kubernetes Ingress and Istio Ingress Gateway serve as entry points for traffic into a cluster, but they cater to different use cases. Kubernetes Ingress is simpler and suited for basic routing needs, whereas Istio Ingress Gateway provides advanced security, traffic management, and observability features—making it ideal for service mesh environments. Choosing between them depends on your traffic control, security, and observability requirements.