Regarding graceful shutdown (introduced in Go 1.8), a bit more concrete example:
package main
import (
"context"
"io"
"log"
"net/http"
"sync"
"time"
)
func startHttpServer(wg *sync.WaitGroup) *http.Server {
srv := &http.Server{Addr: ":8080"}
http.HandleFunc("https://stackoverflow.com/", func(w http.ResponseWriter, r *http.Request) {
io.WriteString(w, "hello world\n")
})
go func() {
defer wg.Done() // let main know we are done cleaning up
// always returns error. ErrServerClosed on graceful close
if err := srv.ListenAndServe(); err != http.ErrServerClosed {
// unexpected error. port in use?
log.Fatalf("ListenAndServe(): %v", err)
}
}()
// returning reference so caller can call Shutdown()
return srv
}
func main() {
log.Printf("main: starting HTTP server")
httpServerExitDone := &sync.WaitGroup{}
httpServerExitDone.Add(1)
srv := startHttpServer(httpServerExitDone)
log.Printf("main: serving for 10 seconds")
time.Sleep(10 * time.Second)
log.Printf("main: stopping HTTP server")
// now close the server gracefully ("shutdown")
// timeout could be given with a proper context
// (in real world you shouldn't use TODO()).
if err := srv.Shutdown(context.TODO()); err != nil {
panic(err) // failure/timeout shutting down the server gracefully
}
// wait for goroutine started in startHttpServer() to stop
httpServerExitDone.Wait()
log.Printf("main: done. exiting")
}