storagenode-updater: respond to Windows Service events (#3077)

cmd/storagenode-updater/main.go

@@ -32,6 +32,8 @@ import (
 )
 
 var (
+	cancel context.CancelFunc
+
 	rootCmd = &cobra.Command{
 		Use:   "storagenode-updater",
 		Short: "Version updater for storage node",
@@ -81,7 +83,8 @@ func cmdRun(cmd *cobra.Command, args []string) (err error) {
 		return errs.New("unable to find storage node executable binary")
 	}
 
-	ctx, cancel := context.WithCancel(context.Background())
+	var ctx context.Context
+	ctx, cancel = context.WithCancel(context.Background())
 	c := make(chan os.Signal, 1)
 	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
 

cmd/storagenode-updater/windows.go

@@ -0,0 +1,74 @@
+// Copyright (C) 2019 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+// Implements support for running the storagenode-updater as a Windows Service.
+//
+// The Windows Service can be created with sc.exe, e.g.
+//
+// sc.exe create storagenode-updater binpath= "C:\Users\MyUser\storagenode-updater.exe run ..."
+
+// +build windows
+
+package main
+
+import (
+	"time"
+	"log"
+
+	"golang.org/x/sys/windows/svc"
+)
+
+func init() {
+	interactive, err := svc.IsAnInteractiveSession()
+	if err != nil {
+		panic("Failed to determine if session is interactive:" + err.Error())
+	}
+
+	if interactive {
+		return
+	}
+
+	err = svc.Run("storagenode-updater", &service{})
+	if err != nil {
+		panic("Service failed: " + err.Error())
+	}
+}
+
+type service struct{}
+
+func (m *service) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (ssec bool, errno uint32) {
+	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown
+
+	changes <- svc.Status{State: svc.StartPending}
+
+	go func() {
+		_ = rootCmd.Execute()
+	}()
+
+	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
+
+	for {
+		select {
+		case c := <-r:
+			switch c.Cmd {
+			case svc.Interrogate:
+				log.Println("Interrogate request received.")
+				changes <- c.CurrentStatus
+				// Testing deadlock from https://code.google.com/p/winsvc/issues/detail?id=4
+				time.Sleep(100 * time.Millisecond)
+				changes <- c.CurrentStatus
+			case svc.Stop, svc.Shutdown:
+				log.Println("Stop/Shutdown request received.")
+				changes <- svc.Status{State: svc.StopPending}
+
+				cancel()
+				// Sleep some time to give chance for goroutines finish cleanup after cancelling the context
+				time.Sleep(3 * time.Second)
+				// After returning the Windows Service is stopped and the process terminates
+				return
+			default:
+				log.Println("Unexpected control request:", c)
+			}
+		}
+	}
+}