Graceful Shutdown Experiment

deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: graceful-shutdown
  labels:
    app: graceful-shutdown
spec:
  replicas: 1
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  selector:
    matchLabels:
      app: graceful-shutdown
  template:
    metadata:
      labels:
        app: graceful-shutdown
    spec:
      containers:
      - name: graceful-shudown
        args:
        - --shutdown.delay=5
        image: salachike/graceful-shudown:v0.0.1
        ports:
        - containerPort: 8080

Dockerfile

FROM golang:1.19.4-alpine3.16 as builder
COPY ./main.go ./
RUN go build -o /app ./main.go

FROM alpine:3.16
COPY --from=builder /app .
USER nobody
ENTRYPOINT ["./app"]
CMD ["--shutdown.delay=0"]

ingress.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: graceful-shutdown 
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
  rules:
  - host: graceful.shutdown.test.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: graceful-shutdown
            port:
              number: 80

main.go

package main

import (
	"context"
	"flag"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"
)

func main() {
	var t time.Duration
	flag.DurationVar(&t, "shutdown.delay", 0, "duration until shutdown starts")
	flag.Parse()

	srv := http.Server{
		Addr: ":8080",
		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w.Write([]byte("hello world"))
		}),
	}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	go func() {
		log.Println("Server is running")
		if err := srv.ListenAndServe(); err != http.ErrServerClosed {
			log.Fatal(err)
		}
	}()

	for {
		select {
		case <-ctx.Done():
			time.Sleep(t)
			srv.Shutdown(ctx)
			return
		}
	}
}

service.yaml

apiVersion: v1
kind: Service
metadata:
  labels:
    app: graceful-shutdown
  name: graceful-shutdown
spec:
  selector:
    app: graceful-shutdown
  type: NodePort
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080