Understanding Kubernetes: Part 18 -Ingress Controller

If you’ve been following our Kubernetes series 2025, welcome back! For new readers, check out Part 16: Understanding Kubernetes: Ingress

📖 Not a Medium member? No worries! Here’s the free link: Part 17 — Ingress Controller

What is an Ingress Controller in Kubernetes?

An Ingress Controller is a component in Kubernetes responsible for implementing the Ingress resource, processing its rules, and directing traffic accordingly. It acts as a reverse proxy, routing HTTP/HTTPS traffic based on defined Ingress rules. While an Ingress resource defines how traffic should be routed, the Ingress Controller enforces those rules and manages actual traffic flow within the cluster.

Kubernetes does not provide a default Ingress Controller; users need to deploy one such as Nginx, Traefik, HAProxy, AWS ALB, or GCP HTTP(S) Load Balancer based on their infrastructure requirements.

Example Use Case:

Suppose you have an Ingress resource configured to expose multiple microservices under a single domain. The Ingress Controller (e.g., Nginx) will:

• Listen to external traffic requests on port 80/443.

• Analyze the Ingress resource configuration.

• Route requests to appropriate backend services based on host/path rules.

• Provide TLS termination for secure access.

Capabilities of Ingress Controller:

1. Traffic Routing:

• Routes incoming requests based on domain names and URL paths as defined in the Ingress resource.

2. TLS Termination:

• Offloads HTTPS processing and provides SSL/TLS encryption using certificates.

3. Load Balancing:

• Distributes traffic across backend pods, ensuring scalability and reliability.

4. Annotations for Advanced Features:

• Supports configuration via annotations (e.g., rate limiting, access control).

5. Security Features:

• Provides authentication, authorization, and DDoS protection mechanisms.

6. Monitoring & Logging:

• Integrates with tools like Prometheus, Grafana, and Fluentd for observability.

Popular Ingress Controllers:

1. Nginx Ingress Controller:

• Most widely used, offering robust routing, security, and easy integration.

2. Traefik:

• Lightweight with automatic discovery, dynamic configuration, and built-in observability.

3. HAProxy:

• High-performance load balancer with extensive traffic management features.

4. AWS ALB Ingress Controller:

• Provides AWS-native integration with Elastic Load Balancer (ALB).

5. GCE Ingress Controller:

• Google Cloud-specific Ingress Controller that integrates with GCP Load Balancing.

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YAML Example — Nginx Ingress Controller Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  namespace: ingress-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx-ingress
  template:
    metadata:
      labels:
        app: nginx-ingress
    spec:
      containers:
      - name: nginx-ingress
        image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:latest
        args:
          - /nginx-ingress-controller
          - --configmap=$(POD_NAMESPACE)/nginx-config
        env:
          - name: POD_NAMESPACE
            valueFrom:
              fieldRef:
                fieldPath: metadata.namespace
        ports:
          - name: http
            containerPort: 80
          - name: https
            containerPort: 443

Explanation:

• Deploys an Nginx Ingress Controller pod that listens on HTTP (80) and HTTPS (443).

• Uses environment variables to dynamically configure namespaces.

• Requires a ConfigMap to store custom Nginx configurations.

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In My Previous Role:

As a Senior DevOps Engineer, I deployed and managed Ingress Controllers (Nginx and AWS ALB) to provide seamless traffic management across Kubernetes clusters. Some of the key contributions included:

• Implemented Nginx Ingress Controller for handling millions of requests daily with zero downtime.

• Automated SSL certificate management using Cert-Manager for HTTPS traffic.

• Integrated AWS ALB Ingress Controller to optimize traffic routing across multi-region environments.

• Fine-tuned Ingress configurations to ensure load balancing, rate limiting, and security hardening.

• Leveraged monitoring tools (Prometheus, Grafana) to track traffic patterns and optimize scaling strategies.

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