refactor(flexvolume): simplify capabilities handling

pkg/volume/flexvolume/BUILD

@@ -42,6 +42,7 @@ go_test(
         "attacher_test.go",
         "common_test.go",
         "detacher_test.go",
+        "driver-call_test.go",
         "flexvolume_test.go",
         "mounter_test.go",
         "plugin_test.go",

pkg/volume/flexvolume/driver-call.go

@@ -58,9 +58,6 @@ const (
 	optionKeyPodUID       = "kubernetes.io/pod.uid"
 
 	optionKeyServiceAccountName = "kubernetes.io/serviceAccount.name"
-
-	attachCapability         = "attach"
-	selinuxRelabelCapability = "selinuxRelabel"
 )
 
 const (
@@ -83,11 +80,6 @@ type DriverCall struct {
 	args    []string
 }
 
-type driverCapabilities struct {
-	attach         bool
-	selinuxRelabel bool
-}
-
 func (plugin *flexVolumePlugin) NewDriverCall(command string) *DriverCall {
 	return plugin.NewDriverCallWithTimeout(command, 0)
 }
@@ -210,7 +202,19 @@ type DriverStatus struct {
 	// Returns capabilities of the driver.
 	// By default we assume all the capabilities are supported.
 	// If the plugin does not support a capability, it can return false for that capability.
-	Capabilities map[string]bool
+	Capabilities *DriverCapabilities `json:",omitempty"`
+}
+
+type DriverCapabilities struct {
+	Attach         bool `json:"attach"`
+	SELinuxRelabel bool `json:"selinuxRelabel"`
+}
+
+func defaultCapabilities() *DriverCapabilities {
+	return &DriverCapabilities{
+		Attach:         true,
+		SELinuxRelabel: true,
+	}
 }
 
 // isCmdNotSupportedErr checks if the error corresponds to command not supported by
@@ -226,7 +230,9 @@ func isCmdNotSupportedErr(err error) bool {
 // handleCmdResponse processes the command output and returns the appropriate
 // error code or message.
 func handleCmdResponse(cmd string, output []byte) (*DriverStatus, error) {
-	var status DriverStatus
+	status := DriverStatus{
+		Capabilities: defaultCapabilities(),
+	}
 	if err := json.Unmarshal(output, &status); err != nil {
 		glog.Errorf("Failed to unmarshal output for command: %s, output: %q, error: %s", cmd, string(output), err.Error())
 		return nil, err
@@ -241,23 +247,3 @@ func handleCmdResponse(cmd string, output []byte) (*DriverStatus, error) {
 
 	return &status, nil
 }
-
-// getDriverCapabilities returns the reported capabilities as returned by driver's init() function
-func (ds *DriverStatus) getDriverCapabilities() *driverCapabilities {
-	driverCaps := &driverCapabilities{
-		attach:         true,
-		selinuxRelabel: true,
-	}
-
-	// Check if driver supports SELinux Relabeling of mounted volume
-	if dcap, ok := ds.Capabilities[selinuxRelabelCapability]; ok {
-		driverCaps.selinuxRelabel = dcap
-	}
-
-	// Check whether the plugin is attachable.
-	if dcap, ok := ds.Capabilities[attachCapability]; ok {
-		driverCaps.attach = dcap
-	}
-
-	return driverCaps
-}

pkg/volume/flexvolume/driver-call_test.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package flexvolume
+
+import (
+	"testing"
+)
+
+func TestHandleResponseDefaults(t *testing.T) {
+	ds, err := handleCmdResponse("test", []byte(`{"status": "Success"}`))
+	if err != nil {
+		t.Error("error: ", err)
+	}
+
+	if *ds.Capabilities != *defaultCapabilities() {
+		t.Error("wrong default capabilities: ", *ds.Capabilities)
+	}
+}

pkg/volume/flexvolume/mounter-defaults.go

@@ -47,7 +47,7 @@ func (f *mounterDefaults) GetAttributes() volume.Attributes {
 	return volume.Attributes{
 		ReadOnly:        f.readOnly,
 		Managed:         !f.readOnly,
-		SupportsSELinux: f.flexVolume.plugin.capabilities.selinuxRelabel,
+		SupportsSELinux: f.flexVolume.plugin.capabilities.SELinuxRelabel,
 	}
 }
 

pkg/volume/flexvolume/plugin.go

@@ -42,8 +42,8 @@ type flexVolumePlugin struct {
 	runner     exec.Interface
 
 	sync.Mutex
-	capabilities        *driverCapabilities
 	unsupportedCommands []string
+	capabilities        DriverCapabilities
 }
 
 type flexVolumeAttachablePlugin struct {
@@ -65,19 +65,16 @@ func NewFlexVolumePlugin(pluginDir, name string) (volume.VolumePlugin, error) {
 		unsupportedCommands: []string{},
 	}
 
-	// Retrieve driver reported capabilities
+	// Initialize the plugin and probe the capabilities
 	call := flexPlugin.NewDriverCall(initCmd)
 	ds, err := call.Run()
 	if err != nil {
 		return nil, err
 	}
+	flexPlugin.capabilities = *ds.Capabilities
 
-	driverCaps := ds.getDriverCapabilities()
+	if flexPlugin.capabilities.Attach {
-	flexPlugin.capabilities = driverCaps
+		// Plugin supports attach/detach, so return flexVolumeAttachablePlugin
-
-	// Check whether the plugin is attachable.
-	if driverCaps.attach {
-		// Plugin supports attach/detach by default, so return flexVolumeAttachablePlugin
 		return &flexVolumeAttachablePlugin{flexVolumePlugin: flexPlugin}, nil
 	} else {
 		return flexPlugin, nil