Implement support for running geesefs OUTSIDE of the container using systemd to not crash mountpoints when csi-s3 is upgraded or restarted

pkg/mounter/geesefs.go

@@ -3,6 +3,11 @@ package mounter
 import (
 	"fmt"
 	"os"
+	"strings"
+	"time"
+
+	systemd "github.com/coreos/go-systemd/v22/dbus"
+	dbus "github.com/godbus/dbus/v5"
 
 	"github.com/yandex-cloud/k8s-csi-s3/pkg/s3"
 )
@@ -38,19 +43,109 @@ func (geesefs *geesefsMounter) Unstage(stageTarget string) error {
 	return nil
 }
 
-func (geesefs *geesefsMounter) Mount(source string, target string) error {
-	fullPath := fmt.Sprintf("%s:%s", geesefs.meta.BucketName, geesefs.meta.Prefix)
-	args := []string{
+func (geesefs *geesefsMounter) CopyBinary(from, to string) error {
+	st, err := os.Stat(from)
+	if err != nil {
+		return fmt.Errorf("Failed to stat %s: %v", from, err)
+	}
+	st2, err := os.Stat(to)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("Failed to stat %s: %v", to, err)
+	}
+	if err != nil || st2.Size() != st.Size() || st2.ModTime() != st.ModTime() {
+		if err == nil {
+			// remove the file first to not hit "text file busy" errors
+			err = os.Remove(to)
+			if err != nil {
+				return fmt.Errorf("Error removing %s to update it: %v", to, err)
+			}
+		}
+		bin, err := os.ReadFile(from)
+		if err != nil {
+			return fmt.Errorf("Error copying %s to %s: %v", from, to, err)
+		}
+		err = os.WriteFile(to, bin, 0755)
+		if err != nil {
+			return fmt.Errorf("Error copying %s to %s: %v", from, to, err)
+		}
+		err = os.Chtimes(to, st.ModTime(), st.ModTime())
+		if err != nil {
+			return fmt.Errorf("Error copying %s to %s: %v", from, to, err)
+		}
+	}
+	return nil
+}
+
+func (geesefs *geesefsMounter) MountDirect(target string, args []string) error {
+	args = append([]string{
 		"--endpoint", geesefs.endpoint,
 		"-o", "allow_other",
 		"--log-file", "/dev/stderr",
-	}
-	if geesefs.region != "" {
-		args = append(args, "--region", geesefs.region)
-	}
-	args = append(args, geesefs.meta.MountOptions...)
-	args = append(args, fullPath, target)
+	}, args...)
 	os.Setenv("AWS_ACCESS_KEY_ID", geesefs.accessKeyID)
 	os.Setenv("AWS_SECRET_ACCESS_KEY", geesefs.secretAccessKey)
 	return fuseMount(target, geesefsCmd, args)
 }
+
+func (geesefs *geesefsMounter) Mount(source, target, volumeID string) error {
+	fullPath := fmt.Sprintf("%s:%s", geesefs.meta.BucketName, geesefs.meta.Prefix)
+	var args []string
+	if geesefs.region != "" {
+		args = append(args, "--region", geesefs.region)
+	}
+	useSystemd := true
+	for i := 0; i < len(geesefs.meta.MountOptions); i++ {
+		if geesefs.meta.MountOptions[i] == "--no-systemd" {
+			useSystemd = false
+		} else {
+			args = append(args, geesefs.meta.MountOptions[i])
+		}
+	}
+	args = append(args, fullPath, target)
+	// Try to start geesefs using systemd so it doesn't get killed when the container exits
+	if !useSystemd {
+		return geesefs.MountDirect(target, args)
+	}
+	conn, err := systemd.New()
+	if err != nil {
+		fmt.Printf("Failed to connect to systemd dbus service: %v, starting geesefs directly\n", err)
+		return geesefs.MountDirect(target, args)
+	}
+	defer conn.Close()
+	// systemd is present
+	if err = geesefs.CopyBinary("/usr/bin/geesefs", "/csi/geesefs"); err != nil {
+		return err
+	}
+	pluginDir := os.Getenv("PLUGIN_DIR")
+	if pluginDir == "" {
+		pluginDir = "/var/lib/kubelet/plugins/ru.yandex.s3.csi"
+	}
+	args = append([]string{pluginDir+"/geesefs", "-f", "-o", "allow_other", "--endpoint", geesefs.endpoint}, args...)
+	unitName := "geesefs-"+systemd.PathBusEscape(volumeID)+".service"
+	props := []systemd.Property{
+		systemd.Property{
+			Name: "Description",
+			Value: dbus.MakeVariant("GeeseFS mount for Kubernetes volume "+volumeID),
+		},
+		systemd.PropExecStart(args, false),
+		systemd.Property{
+			Name: "Environment",
+			Value: dbus.MakeVariant([]string{ "AWS_ACCESS_KEY_ID="+geesefs.accessKeyID, "AWS_SECRET_ACCESS_KEY="+geesefs.secretAccessKey }),
+		},
+		systemd.Property{
+			Name: "CollectMode",
+			Value: dbus.MakeVariant("inactive-or-failed"),
+		},
+	}
+	_, err = conn.StartTransientUnit(unitName, "replace", props, nil)
+	if err != nil && strings.Contains(err.Error(), "already exists") {
+		// Stop and garbage collect the unit if automatic collection didn't work for some reason
+		conn.StopUnit(unitName, "replace", nil)
+		conn.ResetFailedUnit(unitName)
+		_, err = conn.StartTransientUnit(unitName, "replace", props, nil)
+	}
+	if err != nil {
+		return fmt.Errorf("Error starting systemd unit %s on host: %v", unitName, err)
+	}
+	return waitForMount(target, 10*time.Second)
+}