github.com/cic-sap/go-hot-reload

go-hot-reload

Keep the pid of the process, replace the executable file

example code

package main

import _ "embed"
import (
	"fmt"
	reload "github.com/cic-sap/go-hot-reload/v1"

	"log"
	"net/http"
	"os"
	"time"
)

import "github.com/gin-gonic/gin"

//go:embed ver.txt
var ver string

func main() {

	log.Println("start")
	log.SetFlags(log.Lshortfile | log.LstdFlags)
	go reload.AutoReload()

	// your app code ...
	go func() {
		for {
			time.Sleep(time.Second)
			log.Println("ver", ver, "pid", os.Getpid())
		}
	}()

	r := gin.Default()

	r.GET("/", func(c *gin.Context) {
		c.String(http.StatusOK, fmt.Sprintf("hello ver:%s", ver))
	})

	r.Run("0.0.0.0:2345")

	log.Println("end")
}

How to replace k8s pod process online

example

build-new:
	date +"%H:%M:%S" > ver.txt
	go build -o example.new .

http-hot_reload:build-new
	curl  http://127.0.0.1:8087/upload  -F "file=@./example.new" -v

set -ex
export KUBECONFIG=~/.kube/kubeconfig--gcp01.yaml

(GOOS=linux go build -o myapp main.go ;mv myapp myapp.tmp;gzip -fv myapp.tmp) &

name=`kubectl get pods  -n ns1 -l app=myapp -o=jsonpath='{.items[0].metadata.name}'`
wait
kubectl get pods  -n ns1 -l app=myapp &

kubectl -n ns1 cp  myapp.tmp.gz  $name:/usr/local/bin/myapp.tmp.gz
kubectl -n ns1 exec  $name --  sh -x -c 'cd /usr/local/bin/;pwd;ls -alh myapp*;gzip -f -d -v myapp.tmp.gz;mv -f -v myapp.tmp myapp;ls -alh myapp*;'