Avoid code which looks at local files when etcd is configured (#7144)

This situation happens only in gateway nas which supports
etcd based `config.json` to support all FS mode features.

The issue was we would try to migrate something which doesn't
exist when etcd is configured which leads to inconsistent
server configs in memory.

This PR fixes this situation by properly loading config after
initialization, avoiding backend disk config migration to be
done only if etcd is not configured.

cmd/config-common.go

@@ -103,9 +103,8 @@ func readConfigEtcd(ctx context.Context, client *etcd.Client, configFile string)
 	return nil, errConfigNotFound
 }
 
-// watchConfig - watches for changes on `configFile` on etcd and loads them.
-func watchConfig(objAPI ObjectLayer, configFile string, loadCfgFn func(ObjectLayer) error) {
-	if globalEtcdClient != nil {
+// watchConfigEtcd - watches for changes on `configFile` on etcd and loads them.
+func watchConfigEtcd(objAPI ObjectLayer, configFile string, loadCfgFn func(ObjectLayer) error) {
 	ctx, cancel := context.WithTimeout(context.Background(), defaultContextTimeout)
 	defer cancel()
 	for watchResp := range globalEtcdClient.Watch(ctx, configFile) {
@@ -116,7 +115,6 @@ func watchConfig(objAPI ObjectLayer, configFile string, loadCfgFn func(ObjectLay
 		}
 	}
 }
-}
 
 func checkConfigEtcd(ctx context.Context, client *etcd.Client, configFile string) error {
 	timeoutCtx, cancel := context.WithTimeout(ctx, defaultContextTimeout)

cmd/config-current.go

@@ -545,11 +545,8 @@ func (s *serverConfig) loadToCachedConfigs() {
 		globalIsCompressionEnabled = compressionConf.Enabled
 	}
 
-	if globalIAMValidators == nil {
 	globalIAMValidators = getAuthValidators(s)
-	}
 
-	if globalPolicyOPA == nil {
 	if s.Policy.OPA.URL != nil && s.Policy.OPA.URL.String() != "" {
 		globalPolicyOPA = iampolicy.NewOpa(iampolicy.OpaArgs{
 			URL:         s.Policy.OPA.URL,
@@ -559,7 +556,6 @@ func (s *serverConfig) loadToCachedConfigs() {
 		})
 	}
 }
-}
 
 // newSrvConfig - initialize a new server config, saves env parameters if
 // found, otherwise use default parameters

cmd/config.go

@@ -157,6 +157,8 @@ func initConfig(objAPI ObjectLayer) error {
 		return errServerNotInitialized
 	}
 
+	configFile := path.Join(minioConfigPrefix, minioConfigFile)
+
 	if globalEtcdClient != nil {
 		if err := checkConfigEtcd(context.Background(), globalEtcdClient, getConfigFile()); err != nil {
 			if err == errConfigNotFound {
@@ -172,6 +174,10 @@ func initConfig(objAPI ObjectLayer) error {
 				return err
 			}
 		}
+
+		// Watch config for changes and reloads them.
+		go watchConfigEtcd(objAPI, configFile, loadConfig)
+
 	} else {
 		if isFile(getConfigFile()) {
 			if err := migrateConfig(); err != nil {
@@ -184,16 +190,12 @@ func initConfig(objAPI ObjectLayer) error {
 		if err := migrateConfigToMinioSys(objAPI); err != nil {
 			return err
 		}
-	}
-
-	configFile := path.Join(minioConfigPrefix, minioConfigFile)
-
-	// Watch config for changes and reloads them in-memory.
-	go watchConfig(objAPI, configFile, loadConfig)
 
+		// Migrates backend '<export_path>/.minio.sys/config/config.json' to latest version.
 		if err := migrateMinioSysConfig(objAPI); err != nil {
 			return err
 		}
+	}
 
 	return loadConfig(objAPI)
 }

cmd/gateway-main.go

@@ -223,7 +223,7 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 		globalConfigSys = NewConfigSys()
 
 		// Load globalServerConfig from etcd
-		_ = globalConfigSys.Init(newObject)
+		logger.LogIf(context.Background(), globalConfigSys.Init(newObject))
 	}
 
 	// Load logger subsystem
@@ -247,7 +247,7 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 	globalIAMSys = NewIAMSys()
 	if enableIAMOps {
 		// Initialize IAM sys.
-		_ = globalIAMSys.Init(newObject)
+		logger.LogIf(context.Background(), globalIAMSys.Init(newObject))
 	}
 
 	// Create new policy system.
@@ -259,7 +259,7 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 	// Create new notification system.
 	globalNotificationSys = NewNotificationSys(globalServerConfig, globalEndpoints)
 	if globalEtcdClient != nil && newObject.IsNotificationSupported() {
-		_ = globalNotificationSys.Init(newObject)
+		logger.LogIf(context.Background(), globalNotificationSys.Init(newObject))
 	}
 
 	// Encryption support checks in gateway mode.