# Day 27 - Kubernetes Ingress

## **1\. Why People Find Kubernetes Ingress Difficult**

Two reasons:

1. They don’t understand **why Ingress is required**.
    
2. Practical setup fails on Minikube or local clusters because **Ingress controller is missing**.
    

---

## **2\. Before Ingress (Before Kubernetes v1.1)**

People used Kubernetes with:

* **Deployment** → creates Pods
    
* **Service** → exposes Pods, provides internal/external LB using kube-proxy
    

Everything worked fine **until real production needs appeared**.

---

## **3\. Problems People Faced With ONLY Services**

### **Problem 1 — Missing Enterprise Load Balancing Features**

Traditional VM-based environments had powerful load balancers like:

* **Nginx (as LB)**
    
* **F5**
    
* **HAProxy**
    
* **Traefik**
    

These offered advanced features:

* Path-based routing `/a → service1`, `/b → service2`
    
* Host-based routing [`app.example.com`](http://app.example.com) `→ service1`
    
* Sticky sessions
    
* Weighted/rationed load balancing (70/30)
    
* Whitelisting / blacklisting
    
* TLS/HTTPS termination
    
* WAF  
    ...and many more
    

Kubernetes **Services** DID NOT support these.  
Service only does **simple round-robin load balancing** using `kube-proxy`.

This made enterprises **unhappy**.

---

### **Problem 2 — Huge Cost with LoadBalancer Services**

When using:

```plaintext
type: LoadBalancer
```

Every Service gets a **public static IP**.

In large companies:

* 1000 services = 1000 load balancers = huge cloud cost  
    Cloud providers charge for every static LB IP.
    

In VMs earlier:

* They used **one load balancer** for all apps.
    
* Routing done by path/host rules.
    

So Kubernetes LoadBalancer type became **too expensive**.

---

## **4\. Kubernetes Adds a New Concept → INGRESS**

To solve above two problems.

Kubernetes said:

* “We will let users create a **Ingress resource**”
    
* But Kubernetes will **not implement LB logic** for all vendors.
    
* Instead, LB companies must create **Ingress Controllers**.
    

---

## **5\. What is an Ingress Controller?**

A **load balancer implementation** inside Kubernetes.

Examples:

* NGINX Ingress Controller
    
* HAProxy Ingress Controller
    
* Traefik
    
* F5 BIG-IP Ingress
    
* Ambassador
    
* Apache APISIX
    

Workflow:

1. **User creates Ingress resource** (rules like path/host/TLS).
    
2. **Ingress controller reads those rules**.
    
3. **Ingress controller configures the load balancer** inside the cluster.
    

Without an Ingress controller:

* Ingress **does nothing**.
    

---

## **6\. Practical Understanding (Extremely Important)**

Just like:

* Pods → handled by Kubelet
    
* Services → handled by kube-proxy
    
* Deployments → handled by deployment-controller
    

Ingress → MUST be handled by **Ingress Controller**.

So:  
✔ You can create 100 Ingress YAML files  
✖ Nothing will work  
❗ Unless the Ingress controller is installed.

---

## **7\. Common Ingress Controller Installation (Minikube Example)**

On Minikube, installation is simple:

```plaintext
minikube addons enable ingress
```

This deploys:

* `nginx-ingress-controller` Pod
    
* In namespace `ingress-nginx`
    

After this:

* Ingress controller starts watching your Ingress rules
    
* Updates routing internally
    

---

## **8\. Example of the Ingress Resource in Your Content**

You created:

* Deployment → Pod
    
* Service → NodePort
    
* Ingress → Host-based routing ([`foo.bar.com`](http://foo.bar.com))
    

Ingress YAML points to:

```plaintext
serviceName: my-service
servicePort: 80
path: /bar
host: foo.bar.com
```

---

## **9\. After Ingress Controller Installs**

* Ingress now gets an **Address (IP)**.
    
* Ingress controller logs show:
    
    ```plaintext
    Successfully synced ingress: Ingress example
    ```
    

This means:

* Controller picked up your Ingress rule
    
* Updated its internal Nginx config
    

---

## **10\. Accessing Ingress on Local Machine**

Because DNS is not real on local environment:

* You MUST update `/etc/hosts` file
    
* Map your domain ([`foo.bar.com`](http://foo.bar.com)) to Ingress IP
    

Example:

```plaintext
192.168.64.11 foo.bar.com
```

Then you can access:

```plaintext
http://foo.bar.com/bar
```

---

## **11\. Summary — What You Should Remember**

### **Ingress solves two major problems**

1. Missing enterprise-grade LB features
    
2. High cost of cloud LB for each service
    

### **Ingress requires Ingress Controller**

Without it → Ingress does nothing.

### **Ingress Controller = Load Balancer + API Gateway inside Kubernetes**

### **One Ingress can route traffic to MANY services**

Using host/path rules.