HDC Kubernetes Demo

README.md

This demo is an HTTP server that exposes some environment variables from Kubernetes.

Slides

With presenter notes: http://static.velvetcache.org.s3.amazonaws.com/talks/2017/kubernetes-hdc.pdf

Without presenter notes: http://static.velvetcache.org.s3.amazonaws.com/talks/2017/kubernetes-hdc-no-notes.pdf

deployment.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: kubernetes-demo
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: kubernetes-demo
    spec:
      containers:
        - name: kubernetes-demo
          image: jmhobbs/kubernetes-demo:latest
          imagePullPolicy: Always
          ports:
            - containerPort: 8080
          env:
            - name: MESSAGE
              value: "Hello World!"
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name

Dockerfile

FROM scratch
ADD main /
EXPOSE 8080
CMD ["/main"]

main.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"time"
)

type response struct {
	Message string
	Pod     string
}

func main() {
	http.Handle("/", http.HandlerFunc(handler))
	log.Println("Listening on :8080")
	http.ListenAndServe(":8080", nil)
}

func handler(w http.ResponseWriter, r *http.Request) {
	log.Printf("%s %s - %s \n", r.Method, r.URL, r.RemoteAddr)
	w.Header()["Content-Type"] = []string{"text/plain"}
	w.Header()["Cache-Control"] = []string{"no-cache"}
	w.Header()["Refresh"] = []string{"1"}

	if r.URL.Path != "/" {
		w.WriteHeader(http.StatusNotFound)
		w.Write([]byte("404 - Not Found"))
		return
	}

	resp := response{os.Getenv("MESSAGE"), os.Getenv("POD_NAME")}
	if resp.Message == "" {
		resp.Message = "Hello World!"
	}

	fmt.Fprintf(w, "%s\n\nServing from Pod %s\n\n%s", resp.Message, resp.Pod, time.Now().String())
}

service.yaml

apiVersion: v1
kind: Service
metadata:
  name: kubernetes-demo
spec:
  type: LoadBalancer
  selector:
    app: kubernetes-demo
  ports:
  - port: 80
    targetPort: 8080
    protocol: TCP