Accessing Kubernetes service on port 80

Question

I have a Kubernetes service (a Python Flask application) exposed publicly on port 30000 (All Kubernetes NodePorts have to be in the range 30000-32767 from what I understand) using the LoadBalancer type. I need for my public-facing service to be accessible on the standard HTTP port 80. What's the best way to go about doing this?

Answer 1

If you don't use any cloudproviders, you can just set externalIPs option in service and make this IP up on node, and kube-proxy will route traffic from this IP to your pod for you.

{
    "kind": "Service",
    "apiVersion": "v1",
    "metadata": {
        "name": "my-service"
    },
    "spec": {
        "selector": {
            "app": "MyApp"
        },
        "ports": [
            {
                "name": "http",
                "protocol": "TCP",
                "port": 80,
                "targetPort": 9376
            }
        ],
        "externalIPs" : [
            "80.11.12.10"
        ]
    }
}

https://kubernetes.io/docs/concepts/services-networking/service/#external-ips

Answer 2

If you want to use cloud provider's LB, assuming your app expose on port 8080 and you want to publicly expose it on port 80, here is how the configuration should look:

apiVersion: v1
kind: Service
metadata:
  name: flask_app
  labels:
    run: flask_app
  namespace: default
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 8080
    protocol: TCP
    name: http
  selector:
    run: flask_app
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: flask_app
  namespace: default
spec:
  replicas: 1
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
    type: RollingUpdate
  template:
    metadata:
      labels:
        run: flask_app
    spec:
      restartPolicy: Always
      terminationGracePeriodSeconds: 60
      containers:
      - name: flask_app
        image: repo/flask_app:latest
        ports:
        - containerPort: 8080
        imagePullPolicy: Always

Another option is to use a Ingress Controller, for example Nginx.

https://kubernetes.io/docs/concepts/services-networking/ingress/