lib/http: shutdown all servers on exit to remove unix socket

Before this change only serve http was Shutting down its server which
was causing other servers such as serve restic to leave behind their
unix sockets.

This change moves the finalisation to lib/http so all servers have it
and removes it from serve http.

Fixes #6648

cmd/serve/http/http.go

@@ -11,14 +11,12 @@ import (
 	"path"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
 	"github.com/rclone/rclone/cmd"
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/accounting"
-	"github.com/rclone/rclone/lib/atexit"
 	libhttp "github.com/rclone/rclone/lib/http"
 	"github.com/rclone/rclone/lib/http/serve"
 	"github.com/rclone/rclone/vfs"
@@ -82,17 +80,6 @@ control the stats printing.
 				log.Fatal(err)
 			}
 
-			var finaliseOnce sync.Once
-			finalise := func() {
-				finaliseOnce.Do(func() {
-					if err := s.server.Shutdown(); err != nil {
-						log.Printf("error shutting down server: %v", err)
-					}
-				})
-			}
-			fnHandle := atexit.Register(finalise)
-			defer atexit.Unregister(fnHandle)
-
 			s.server.Wait()
 			return nil
 		})

lib/http/server.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/go-chi/chi/v5"
 	"github.com/rclone/rclone/fs/config/flags"
+	"github.com/rclone/rclone/lib/atexit"
 	"github.com/spf13/pflag"
 )
 
@@ -145,6 +146,7 @@ type Server struct {
 	template     *TemplateConfig
 	htmlTemplate *template.Template
 	usingAuth    bool // set if we are using auth middleware
+	atexitHandle atexit.FnHandle
 }
 
 // Option allows customizing the server
@@ -390,6 +392,8 @@ func (s *Server) Serve() {
 		// log.Printf("listening on %s", ii.url)
 		go ii.serve(&s.wg)
 	}
+	// Install an atexit handler to shutdown gracefully
+	s.atexitHandle = atexit.Register(func() { _ = s.Shutdown() })
 }
 
 // Wait blocks while the server is serving requests
@@ -402,14 +406,23 @@ func (s *Server) Router() chi.Router {
 	return s.mux
 }
 
+// Time to wait to Shutdown an HTTP server
+const gracefulShutdownTime = 10 * time.Second
+
 // Shutdown gracefully shuts down the server
 func (s *Server) Shutdown() error {
-	ctx := context.Background()
+	// Stop the atexit handler
+	if s.atexitHandle != nil {
+		atexit.Unregister(s.atexitHandle)
+		s.atexitHandle = nil
+	}
 	for _, ii := range s.instances {
+		expiry := time.Now().Add(gracefulShutdownTime)
+		ctx, cancel := context.WithDeadline(context.Background(), expiry)
 		if err := ii.httpServer.Shutdown(ctx); err != nil {
 			log.Printf("error shutting down server: %s", err)
-			continue
 		}
+		cancel()
 	}
 	s.wg.Wait()
 	return nil