deployment.yaml

kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  labels:
    app: readiness-bug
  name: readiness-bug
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: readiness-bug
    spec:
      containers:
      - name: readiness-bug
        image: broady/k8s-readiness-bug:latest
        imagePullPolicy: Always
        ports:
        - name: http
          containerPort: 8080
        env:
        - name: ANYTHING
          value: something
        readinessProbe:
          httpGet:
            path: /healthz
            port: http
          timeoutSeconds: 1

---
kind: Service
apiVersion: v1
metadata:
  labels:
    app: readiness-bug
  name: readiness-bug
spec:
  type: LoadBalancer
  ports:
  - name: http
    port: 80
    targetPort: http
  selector:
    app: readiness-bug

main.go

package main

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

var startup = time.Now()

func main() {
	http.HandleFunc("/healthz", health)
	http.HandleFunc("/", serve)
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func serve(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "since startup: %s\n", time.Now().Sub(startup))

	for _, e := range os.Environ() {
		fmt.Fprintln(w, e)
	}
}

func health(w http.ResponseWriter, r *http.Request) {
	if time.Now().After(startup.Add(30 * time.Second)) {
		io.WriteString(w, "ok")
		return
	}
	http.Error(w, "starting up", http.StatusServiceUnavailable)
}