[cinder-csi-plugin] Allow --cloud-config to be given multiple times

This change allows cinder-csi-plugin to be invoked with multiple config
files. These will be parsed sequentially in the order specified. Values
in later config files override values in earlier config files.

This makes 'layered' configurations simpler to manage. For example a
base configuration containing authentication information and a per-node
override configuration which applies only to a single node. Keeping
these in separate files simplifies the task of changing the base
configuration for all nodes.

cmd/cinder-csi-plugin/main.go

@@ -34,7 +34,7 @@ import (
 var (
 	endpoint    string
 	nodeID      string
-	cloudconfig string
+	cloudconfig []string
 	cluster     string
 )
 
@@ -80,7 +80,7 @@ func main() {
 	cmd.PersistentFlags().StringVar(&endpoint, "endpoint", "", "CSI endpoint")
 	cmd.MarkPersistentFlagRequired("endpoint")
 
-	cmd.PersistentFlags().StringVar(&cloudconfig, "cloud-config", "", "CSI driver cloud config")
+	cmd.PersistentFlags().StringSliceVar(&cloudconfig, "cloud-config", nil, "CSI driver cloud config")
 	cmd.MarkPersistentFlagRequired("cloud-config")
 
 	cmd.PersistentFlags().StringVar(&cluster, "cluster", "", "The identifier of the cluster that the plugin is running in.")

pkg/csi/cinder/openstack/openstack.go

@@ -90,28 +90,33 @@ func logcfg(cfg Config) {
 	klog.Infof("Block storage opts: %v", cfg.BlockStorage)
 }
 
-// GetConfigFromFile retrieves config options from file
-func GetConfigFromFile(configFilePath string) (Config, error) {
+// GetConfigFromFiles retrieves config options from file
+func GetConfigFromFiles(configFilePaths []string) (Config, error) {
 	var cfg Config
-	config, err := os.Open(configFilePath)
-	if err != nil {
-		klog.Errorf("Failed to open OpenStack configuration file: %v", err)
-		return cfg, err
-	}
-	defer config.Close()
 
-	err = gcfg.FatalOnly(gcfg.ReadInto(&cfg, config))
-	if err != nil {
-		klog.Errorf("Failed to read OpenStack configuration file: %v", err)
-		return cfg, err
+	// Read all specified config files in order. Values from later config files
+	// will overwrite values from earlier ones.
+	for _, configFilePath := range configFilePaths {
+		config, err := os.Open(configFilePath)
+		if err != nil {
+			klog.Errorf("Failed to open OpenStack configuration file: %v", err)
+			return cfg, err
+		}
+		defer config.Close()
+
+		err = gcfg.FatalOnly(gcfg.ReadInto(&cfg, config))
+		if err != nil {
+			klog.Errorf("Failed to read OpenStack configuration file: %v", err)
+			return cfg, err
+		}
 	}
 
 	// Update the config with data from clouds.yaml if UseClouds is enabled
 	if cfg.Global.UseClouds {
 		if cfg.Global.CloudsFile != "" {
 			os.Setenv("OS_CLIENT_CONFIG_FILE", cfg.Global.CloudsFile)
 		}
-		err = client.ReadClouds(&cfg.Global)
+		err := client.ReadClouds(&cfg.Global)
 		if err != nil {
 			return cfg, err
 		}
@@ -124,20 +129,20 @@ func GetConfigFromFile(configFilePath string) (Config, error) {
 const defaultMaxVolAttachLimit int64 = 256
 
 var OsInstance IOpenStack = nil
-var configFile = "/etc/cloud.conf"
+var configFiles = []string{"/etc/cloud.conf"}
 var cfg Config
 
-func InitOpenStackProvider(cfgFile string) {
-	configFile = cfgFile
-	klog.V(2).Infof("InitOpenStackProvider configFile: %s", configFile)
+func InitOpenStackProvider(cfgFiles []string) {
+	configFiles = cfgFiles
+	klog.V(2).Infof("InitOpenStackProvider configFiles: %s", configFiles)
 }
 
 // CreateOpenStackProvider creates Openstack Instance
 func CreateOpenStackProvider() (IOpenStack, error) {
 	// Get config from file
-	cfg, err := GetConfigFromFile(configFile)
+	cfg, err := GetConfigFromFiles(configFiles)
 	if err != nil {
-		klog.Errorf("GetConfigFromFile %s failed with error: %v", configFile, err)
+		klog.Errorf("GetConfigFromFiles %s failed with error: %v", configFiles, err)
 		return nil, err
 	}
 	logcfg(cfg)

pkg/csi/cinder/openstack/openstack_test.go

@@ -28,6 +28,7 @@ import (
 )
 
 var fakeFileName = "cloud.conf"
+var fakeOverrideFileName = "cloud-override.conf"
 var fakeUserName = "user"
 var fakePassword = "pass"
 var fakeAuthUrl = "https://169.254.169.254/identity/v3"
@@ -37,8 +38,8 @@ var fakeRegion = "RegionOne"
 var fakeCAfile = "fake-ca.crt"
 var fakeCloudName = "openstack"
 
-// Test GetConfigFromFile
-func TestGetConfigFromFile(t *testing.T) {
+// Test GetConfigFromFiles
+func TestGetConfigFromFiles(t *testing.T) {
 	// init file
 	var fakeFileContent = `
 [Global]
@@ -76,10 +77,41 @@ rescan-on-resize=true`
 	expectedOpts.Global.Region = fakeRegion
 	expectedOpts.BlockStorage.RescanOnResize = true
 
-	// Invoke GetConfigFromFile
-	actualAuthOpts, err := GetConfigFromFile(fakeFileName)
+	// Invoke GetConfigFromFiles
+	actualAuthOpts, err := GetConfigFromFiles([]string{fakeFileName})
 	if err != nil {
-		t.Errorf("failed to GetConfigFromFile: %v", err)
+		t.Errorf("failed to GetConfigFromFiles: %v", err)
+	}
+
+	// Assert
+	assert.Equal(expectedOpts, actualAuthOpts)
+
+	// Create an override config file
+	var fakeOverrideFileContent = `
+[BlockStorage]
+rescan-on-resize=false`
+
+	f, err = os.Create(fakeOverrideFileName)
+	if err != nil {
+		t.Errorf("failed to create file: %v", err)
+	}
+
+	_, err = f.WriteString(fakeOverrideFileContent)
+	f.Close()
+	if err != nil {
+		t.Errorf("failed to write file: %v", err)
+	}
+	defer os.Remove(fakeOverrideFileName)
+
+	// expectedOpts should reflect the overriden value of rescan-on-resize. All
+	// other values should be the same as before because they come from the
+	// 'base' configuration
+	expectedOpts.BlockStorage.RescanOnResize = false
+
+	// Invoke GetConfigFromFiles with both the base and override config files
+	actualAuthOpts, err = GetConfigFromFiles([]string{fakeFileName, fakeOverrideFileName})
+	if err != nil {
+		t.Errorf("failed to GetConfigFromFiles: %v", err)
 	}
 
 	// Assert
@@ -130,10 +162,10 @@ rescan-on-resize=true`
 	expectedOpts.Global.Cloud = fakeCloudName
 	expectedOpts.BlockStorage.RescanOnResize = true
 
-	// Invoke GetConfigFromFile
-	actualAuthOpts, err := GetConfigFromFile(fakeFileName)
+	// Invoke GetConfigFromFiles
+	actualAuthOpts, err := GetConfigFromFiles([]string{fakeFileName})
 	if err != nil {
-		t.Errorf("failed to GetConfigFromFile: %v", err)
+		t.Errorf("failed to GetConfigFromFiles: %v", err)
 	}
 
 	// Assert