Support using symlinks in storage class to find correct driver

Author: Harvey Lowndes

cmd/oci/main.go

@@ -18,6 +18,9 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"path"
+	"strings"
+	"sync"
 
 	"github.com/oracle/oci-flexvolume-driver/pkg/flexvolume"
 	"github.com/oracle/oci-flexvolume-driver/pkg/oci/driver"
@@ -27,6 +30,12 @@ import (
 var version string
 var build string
 
+// All registered drivers.
+var (
+	driversMutex sync.Mutex
+	drivers      = make(map[string]flexvolume.Driver)
+)
+
 // GetLogPath returns the default path to the driver log file.
 func GetLogPath() string {
 	path := os.Getenv("OCI_FLEXD_DRIVER_LOG_DIR")
@@ -36,6 +45,10 @@ func GetLogPath() string {
 	return path + "/oci_flexvolume_driver.log"
 }
 
+func loadRegisteredDrivers() {
+	registerDriver("oci-bvs", &driver.OCIFlexvolumeDriver{})
+}
+
 func main() {
 	// TODO: Maybe use sirupsen/logrus?
 	f, err := os.OpenFile(GetLogPath(), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
@@ -50,5 +63,58 @@ func main() {
 	log.SetOutput(f)
 
 	log.Printf("OCI FlexVolume Driver version: %s (%s)", version, build)
-	flexvolume.ExecDriver(&driver.OCIFlexvolumeDriver{}, os.Args)
+
+	loadRegisteredDrivers()
+
+	driver, err := getDriverFromArgs()
+	if err != nil {
+		log.Fatalf(err.Error())
+	}
+
+	flexvolume.ExitWithResult(flexvolume.ExecDriver(driver, os.Args))
+}
+
+func getDriverFromArgs() (flexvolume.Driver, error) {
+	driver, err := getRegisteredDriver(flexvolume.DefaultSymlinkDirectory) //Block volume is default
+	if err != nil {
+		return nil, err
+	}
+
+	dir := path.Base(os.Args[0])
+	dir = string(strings.TrimPrefix(dir, "oracle~"))
+
+	if dir != "oci" && dir != flexvolume.DefaultSymlinkDirectory {
+		driver, err = getRegisteredDriver(dir)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	log.Printf("Using %s driver", dir)
+
+	return driver, nil
+}
+
+// getRegisteredDriver returns an instance of the named driver, or nil if
+// the name is unknown. An error is thrown if the named driver is not found.
+func getRegisteredDriver(name string) (flexvolume.Driver, error) {
+	driversMutex.Lock()
+	defer driversMutex.Unlock()
+	f, found := drivers[name]
+	if !found {
+		return nil, fmt.Errorf("No driver found for %s", name)
+	}
+	return f, nil
+}
+
+// registerDriver registers a flexvolume.Driver by name.  This
+// is expected to happen during app startup.
+func registerDriver(name string, driver flexvolume.Driver) {
+	driversMutex.Lock()
+	defer driversMutex.Unlock()
+	if _, found := drivers[name]; found {
+		log.Fatalf("Driver %q was registered twice", name)
+	}
+	log.Printf("Registered driver %q", name)
+	drivers[name] = driver
 }

deploy.sh

@@ -20,7 +20,9 @@ set -o pipefail
 VENDOR=oracle
 DRIVER=oci
 
-driver_dir="/flexmnt/$VENDOR${VENDOR:+"~"}${DRIVER}"
+ORACLE_OCI_FOLDER=$VENDOR${VENDOR:+"~"}${DRIVER}
+
+driver_dir="/flexmnt/$ORACLE_OCI_FOLDER"
 
 LOG_FILE="$driver_dir/oci_flexvolume_driver.log"
 
@@ -33,14 +35,20 @@ if [ ! -d "$driver_dir" ]; then
   mkdir "$driver_dir"
 fi
 
+if [ ! -d "$driver_dir-bvs" ]; then
+  mkdir "$driver_dir-bvs"
+fi
+
 cp "/$DRIVER" "$driver_dir/.$DRIVER"
 mv -f "$driver_dir/.$DRIVER" "$driver_dir/$DRIVER"
 
+ln -sf "../$ORACLE_OCI_FOLDER/$DRIVER" "$driver_dir-bvs/$DRIVER-bvs"
+
 if [ -f "$CONFIG_FILE" ]; then
   cp  "$CONFIG_FILE"  "$driver_dir/$config_file_name"
 fi
 
 while : ; do
   touch $LOG_FILE
   tail -f $LOG_FILE
-done
+done

pkg/flexvolume/flexvolume.go

@@ -67,6 +67,8 @@ const (
 	OptionKeyPodUID       = "kubernetes.io/pod.uid"
 
 	OptionKeyServiceAccountName = "kubernetes.io/serviceAccount.name"
+
+	DefaultSymlinkDirectory = "oci-bvs"
 )
 
 // Driver is the main Flexvolume interface.
@@ -111,6 +113,15 @@ func Fail(a ...interface{}) DriverStatus {
 	}
 }
 
+// Failf creates a StatusFailure Result with a given message.
+func Failf(s string, a ...interface{}) DriverStatus {
+	msg := fmt.Sprintf(s, a...)
+	return DriverStatus{
+		Status:  StatusFailure,
+		Message: msg,
+	}
+}
+
 // Succeed creates a StatusSuccess Result with a given message.
 func Succeed(a ...interface{}) DriverStatus {
 	return DriverStatus{
@@ -119,6 +130,14 @@ func Succeed(a ...interface{}) DriverStatus {
 	}
 }
 
+// NotSupportedf creates a StatusNotSupported Result with a given message.
+func NotSupportedf(s string, a ...interface{}) DriverStatus {
+	return DriverStatus{
+		Status:  StatusNotSupported,
+		Message: fmt.Sprintf(s, a...),
+	}
+}
+
 // NotSupported creates a StatusNotSupported Result with a given message.
 func NotSupported(a ...interface{}) DriverStatus {
 	return DriverStatus{
@@ -143,127 +162,127 @@ func processOpts(optsStr string) (Options, error) {
 
 // ExecDriver executes the appropriate FlexvolumeDriver command based on
 // recieved call-out.
-func ExecDriver(driver Driver, args []string) {
+func ExecDriver(driver Driver, args []string) DriverStatus {
 	if len(args) < 2 {
-		ExitWithResult(Fail("Expected at least one argument"))
+		return Failf("Expected at least one argument")
 	}
 
 	log.Printf("'%s %s' called with %s", args[0], args[1], args[2:])
 
 	switch args[1] {
 	// <driver executable> init
 	case "init":
-		ExitWithResult(driver.Init())
+		return driver.Init()
 
 	// <driver executable> getvolumename <json options>
 	// Currently broken as of lates kube release (1.6.4). Work around hardcodes
 	// exiting with StatusNotSupported.
 	// TODO(apryde): Investigate current situation and version support
 	// requirements.
 	case "getvolumename":
-		ExitWithResult(NotSupported("getvolumename is broken as of kube 1.6.4"))
+		return NotSupportedf("getvolumename is broken as of kube 1.6.4")
 
 	// <driver executable> attach <json options> <node name>
 	case "attach":
 		if len(args) != 4 {
-			ExitWithResult(Fail("attach expected exactly 4 arguments; got ", args))
+			Failf("attach expected exactly 4 arguments; got ", args)
 		}
 
 		opts, err := processOpts(args[2])
 		if err != nil {
-			ExitWithResult(Fail(err))
+			return Failf(err.Error())
 		}
 
 		nodeName := args[3]
-		ExitWithResult(driver.Attach(opts, nodeName))
+		return driver.Attach(opts, nodeName)
 
 	// <driver executable> detach <mount device> <node name>
 	case "detach":
 		if len(args) != 4 {
-			ExitWithResult(Fail("detach expected exactly 4 arguments; got ", args))
+			return Failf("detach expected exactly 4 arguments; got ", args)
 		}
 
 		mountDevice := args[2]
 		nodeName := args[3]
-		ExitWithResult(driver.Detach(mountDevice, nodeName))
+		return driver.Detach(mountDevice, nodeName)
 
 	// <driver executable> waitforattach <mount device> <json options>
 	case "waitforattach":
 		if len(args) != 4 {
-			ExitWithResult(Fail("waitforattach expected exactly 4 arguments; got ", args))
+			return Failf("waitforattach expected exactly 4 arguments; got ", args)
 		}
 
 		mountDevice := args[2]
 		opts, err := processOpts(args[3])
 		if err != nil {
-			ExitWithResult(Fail(err))
+			return Failf(err.Error())
 		}
 
-		ExitWithResult(driver.WaitForAttach(mountDevice, opts))
+		return driver.WaitForAttach(mountDevice, opts)
 
 	// <driver executable> isattached <json options> <node name>
 	case "isattached":
 		if len(args) != 4 {
-			ExitWithResult(Fail("isattached expected exactly 4 arguments; got ", args))
+			return Failf("isattached expected exactly 4 arguments; got ", args)
 		}
 
 		opts, err := processOpts(args[2])
 		if err != nil {
-			ExitWithResult(Fail(err))
+			return Failf(err.Error())
 		}
 		nodeName := args[3]
-		ExitWithResult(driver.IsAttached(opts, nodeName))
+		return driver.IsAttached(opts, nodeName)
 
 	// <driver executable> mountdevice <mount dir> <mount device> <json options>
 	case "mountdevice":
 		if len(args) != 5 {
-			ExitWithResult(Fail("mountdevice expected exactly 5 arguments; got ", args))
+			return Failf("mountdevice expected exactly 5 arguments; got ", args)
 		}
 
 		mountDir := args[2]
 		mountDevice := args[3]
 
 		opts, err := processOpts(args[4])
 		if err != nil {
-			ExitWithResult(Fail(err))
+			return Failf(err.Error())
 		}
 
-		ExitWithResult(driver.MountDevice(mountDir, mountDevice, opts))
+		return driver.MountDevice(mountDir, mountDevice, opts)
 
 	// <driver executable> unmountdevice <mount dir>
 	case "unmountdevice":
 		if len(args) != 3 {
-			ExitWithResult(Fail("unmountdevice expected exactly 3 arguments; got ", args))
+			return Failf("unmountdevice expected exactly 3 arguments; got ", args)
 		}
 
 		mountDir := args[2]
-		ExitWithResult(driver.UnmountDevice(mountDir))
+		return driver.UnmountDevice(mountDir)
 
 	// <driver executable> mount <mount dir> <json options>
 	case "mount":
 		if len(args) != 4 {
-			ExitWithResult(Fail("mount expected exactly 4 arguments; got ", args))
+			return Failf("mount expected exactly 4 arguments; got ", args)
 		}
 
 		mountDir := args[2]
 
 		opts, err := processOpts(args[3])
 		if err != nil {
-			ExitWithResult(Fail(err))
+			return Failf(err.Error())
 		}
 
-		ExitWithResult(driver.Mount(mountDir, opts))
+		return driver.Mount(mountDir, opts)
 
 	// <driver executable> unmount <mount dir>
 	case "unmount":
 		if len(args) != 3 {
-			ExitWithResult(Fail("mount expected exactly 3 arguments; got ", args))
+			return Failf("mount expected exactly 3 arguments; got ", args)
 		}
 
 		mountDir := args[2]
-		ExitWithResult(driver.Unmount(mountDir))
+		return driver.Unmount(mountDir)
 
 	default:
-		ExitWithResult(Fail("Invalid command; got ", args))
+		return Failf("invalid command; got ", args)
 	}
 }