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What is Ingress?

Ingress is a Kubernetes API object that manages external access to services, typically over HTTP and HTTPS.

It acts as an application-layer (Layer 7) router, controlling:

  • URLs / paths
  • Hostnames
  • SSL/TLS termination
  • Load balancing
  • Traffic rules

Ingress allows you to expose multiple Services through a single external IP.

Think of it like an NGINX / Envoy reverse proxy managed by Kubernetes.

Key Characteristics

1. L7 (HTTP/HTTPS) routing

Ingress routes traffic based on:

  • URL path
  • Hostname
  • Subdomain

Examples:

/api → service A  
/ui → service B  
shop.example.com → shop-service

2. Requires an Ingress Controller

  • Ingress is just a rule set. To actually route traffic, you need an Ingress Controller, such as:
    • NGINX
    • HAProxy
    • Traefik
    • Istio (as gateway)
    • AWS/GCP/Azure L7 LB controllers
  • Without a controller, Ingress does nothing.

3. Provides a single entrypoint

Instead of exposing each Service as a NodePort/LoadBalancer, you can use:

  • ONE external IP
  • Handling MANY services This reduces costs and simplifies management.

4. Supports TLS / SSL termination

  • Ingress can perform HTTPS termination using certificates:
tls:
- hosts:
  - example.com
  secretName: tls-secret
  • The Ingress controller handles TLS handshake.

5. Centralized traffic routing rules

Ingress acts as a policy layer where you define:

  • Rate limits
  • Security rules
  • Rewrite rules
  • Redirects
  • Load-balancing behavior

Use Cases

  • ✔ Expose multiple microservices behind one public IP
  • ✔ Host-based routing (api.example.com, app.example.com)
  • ✔ Path-based routing (/auth, /db, /ui)
  • ✔ TLS/HTTPS termination
  • ✔ Reverse proxy behavior
  • ✔ API gateway for microservices
  • ✔ Telecom CNF northbound/southbound interfaces
  • ✔ Ingress for dashboards, UIs, APIs

YAML Definition

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: demo.example.com
    http:
      paths:
      - path: /app
        pathType: Prefix
        backend:
          service:
            name: app-service
            port:
              number: 80