Simple ingress controller

Overview

This is a simple ingress controller for Kubernetes. It watches for Ingress resources and creates a corresponding mapping rule to forward requests.

sequenceDiagram
    participant Local as Local Machine
    participant Ingress as Ingress Controller (DaemonSet)
    participant Service as Backend Server

    Local->>Ingress: curl -k --header "HOST: kaixin.local" https://kaixin.local:8083/v2/endpoint
    Ingress->>Service: Forward request to backend server
    Service-->>Ingress: Response from backend server
    Ingress-->>Local: Response from Ingress Controller

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k3d

This setup uses k3d to create a local k8s cluster. Each docker container is a node in k8s cluster.
Install k3d using the following command:

k3d registry create kaixin-registry --port 12345
k3d cluster create --registry-use k3d-kaixin-registry:12345 -p "8083:32005@loadbalancer" another-kaixin-demo --agents 1

Here is the k8s cluster created by k3d:

Build and run

docker build -f ./deployment/Dockerfile -t kaixin-registry:12345/gateway:v1.0 .
docker push kaixin-registry:12345/gateway:v1.0

kubectl apply -f ./deployment/deployment-app.yaml
kubectl apply -f ./deployment/deployment-ingress-controller.yaml
kubectl apply -f ./deployment/ingress.yaml

Test the ingress controller

curl -k --header "HOST: kaixin.local" https://kaixin.local:8083/v2/endpoint
curl -k --header "HOST: another.local" https://another.local:8083/v2/endpoint

Generate self-signed certificate

openssl genrsa -out ca.key 2048
openssl req -x509 \
  -new -nodes  \
  -days 10000 \
  -key ca.key \
  -out ca.crt \
  -subj "/CN=kaixin.local"

Create k8s secret

kubectl create secret tls tls-cert \
--key ca.key \
--cert ca.crt

References

• How To Call Kubernetes API using Simple HTTP Client
• How to Build a Custom Kubernetes Ingress Controller in Go