Fundamentals⌗

kube-proxy x iptables⌗

kube-proxy x ipvs⌗

Diagram⌗ 


                            +--------------------------+
                            |   External User (Browser)|
                            +--------------------------+
                                        |
                             HTTP/HTTPS to NodeIP:NodePort
                                        |
                                [ Kubernetes Node ]
                                        |
                        +-----------------------------------+
                        |  NodePort Service (Ingress-NGINX) | 
                        |  Type: NodePort                   | 
                        |  Ports: 80 → 30080, 443 → 30443   |
                        +-----------------------------------+
                                        |
                          [ Ingress-NGINX Controller Pod ]
                          (nginx reverse proxy running in pod)
                                        |
                          Matches Ingress rules like:
                            - Host: app.example.com
                            - Path: /api → service/api
                                        |
                      +----------------+----------------+
                      |                                 |
            [ Service: frontend-svc ]        [ Service: api-svc ]
                      |                                 |
                  [ Pod(s): frontend ]           [ Pod(s): backend ]

What is Ingress?⌗

Ingress is a Kubernetes API object that manages external access to services, typically use HTTP or HTTP/S service. It allows you to define rules for routing external traffic to internal services. But Ingress is just a configuration, it doesn’t do the actual routing.

That’s where the Ingress Controller comes in.

What is an Ingress Controller?⌗

An Ingress Controller is a specialized Kubernetes component (usually deployed as a pod) that implements the rules defined in Ingress resources.

In other words:

An Ingress defines what traffic should go where, and the Ingress Controller is the component that makes it happen.

Key Roles of an Ingress Controller⌗

Role Description
💬 Listens for Ingress resources Watches the Kubernetes API for any Ingress definitions
⚙️ Builds a routing config Dynamically builds a reverse proxy configuration (e.g., NGINX, HAProxy)
🚦 Handles external traffic Exposes itself (via NodePort/LoadBalancer) to accept requests from the outside
🚚 Routes traffic to services Based on domain/path rules in Ingress resources
🔐 Can handle HTTPS & TLS Supports automatic TLS with cert-manager or manual certs
🔍 Supports advanced rules Path rewrites, custom headers, authentication, rate-limiting, etc.

common ingress controller:⌗

  • ingress-nginx: ingress-nginx is an Ingress controller for Kubernetes using NGINX as a reverse proxy and load balancer

for example, you can run the following command to install ingress-nginx conroller:

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.8.0/deploy/static/provider/cloud/deploy.yaml

# This sets up:
# - A Pod that runs the NGINX controller.
# - A Service (usually LoadBalancer or NodePort) to expose NGINX to the internet.

How to Inspect the Ingress Nginx Controller⌗ 

# get ingress
sudo kubectl get ingress -n namespace

# describe ingress
sudo kubectl describe ingress -n namespace

# get all deployment (-A is equal to --all-namespaces)
sudo kubectl get deployment -A

# get ingress deployment
sudo kubectl get deployment ingress_name -n namespace -o yaml

What is a NodePort in Kubernetes?⌗

A NodePort is a type of Kubernetes Service that exposes an application running in the cluster on a static port on every node’s IP address.

In simple terms: NodePort maps a port on your Kubernetes node (like 30080) to a pod running inside the cluster.

How to Check the NodePort for Ingress-NGINX⌗ 

# Get the NodePort for the ingress-nginx Service (-n ingress-namespace)
sudo kubectl get svc -n ingress-nginx 

# output means you can access ingress-nginx-controller (pod) port 80 via node (host) port 30080 (http), and port 443 via 30443 (https)
# for example, if the node ip is 192.168.1.10, you can access ingress-nginx-controller via:
# http://192.168.1.10:30080
# https://192.168.1.10:30443
NAME                                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx-controller             NodePort    10.99.184.72     <none>        80:30080/TCP,443:30443/TCP   3d