remove flag and enable flag syncs by default

Signed-off-by: Kavindu Dodanduwa <kavindudodanduwa@gmail.com>

docs/reference/flagd-cli/flagd_start.md

@@ -22,7 +22,6 @@ flagd start [flags]
   -k, --server-key-path string      Server side tls key path
   -d, --socket-path string          Flagd socket path. With grpc the service will become available on this address. With http(s) the grpc-gateway proxy will use this address internally.
   -s, --sources string              JSON representation of an array of SourceConfig objects. This object contains 2 required fields, uri (string) and provider (string). Documentation for this object: https://flagd.dev/reference/sync-configuration/#source-configuration
-  -e, --sync-enabled                Enables the gRPC sync service from flagd. This is disabled by default
   -g, --sync-port int32             gRPC Sync port (default 8015)
   -f, --uri .yaml/.yml/.json        Set a sync provider uri to read data from, this can be a filepath, URL (HTTP and gRPC) or FeatureFlag custom resource. When flag keys are duplicated across multiple providers the merge priority follows the index of the flag arguments, as such flags from the uri at index 0 take the lowest precedence, with duplicated keys being overwritten by those from the uri at index 1. Please note that if you are using filepath, flagd only supports files with .yaml/.yml/.json extension.
 ```

docs/reference/grpc-sync-service.md

@@ -5,7 +5,6 @@ description: flagd as a gRPC sync service
 # Overview
 
 flagd can expose a gRPC sync service, allowing in-process providers to obtain their flag definitions.
-This mode is **disabled** by default, and you can enable it by using startup flag `--sync-enabled` (or `-e` shorthand flag).
 The gRPC sync stream contains flag definitions currently configured at flagd as [sync-configurations](./sync-configuration.md).
 
 ```mermaid

flagd/cmd/start.go

@@ -26,7 +26,6 @@ const (
 	serverKeyPathFlagName  = "server-key-path"
 	socketPathFlagName     = "socket-path"
 	sourcesFlagName        = "sources"
-	syncEnabledFlagName    = "sync-enabled"
 	syncPortFlagName       = "sync-port"
 	uriFlagName            = "uri"
 )
@@ -67,9 +66,6 @@ func init() {
 	flags.StringP(otelCollectorURI, "o", "", "Set the grpc URI of the OpenTelemetry collector "+
 		"for flagd runtime. If unset, the collector setup will be ignored and traces will not be exported.")
 
-	flags.BoolP(syncEnabledFlagName, "e", false, "Enables the gRPC sync service from flagd. "+
-		"This is disabled by default")
-
 	_ = viper.BindPFlag(corsFlagName, flags.Lookup(corsFlagName))
 	_ = viper.BindPFlag(logFormatFlagName, flags.Lookup(logFormatFlagName))
 	_ = viper.BindPFlag(metricsExporter, flags.Lookup(metricsExporter))
@@ -82,7 +78,6 @@ func init() {
 	_ = viper.BindPFlag(sourcesFlagName, flags.Lookup(sourcesFlagName))
 	_ = viper.BindPFlag(uriFlagName, flags.Lookup(uriFlagName))
 	_ = viper.BindPFlag(syncPortFlagName, flags.Lookup(syncPortFlagName))
-	_ = viper.BindPFlag(syncEnabledFlagName, flags.Lookup(syncEnabledFlagName))
 }
 
 // startCmd represents the start command
@@ -138,7 +133,6 @@ var startCmd = &cobra.Command{
 			ServicePort:       viper.GetUint16(portFlagName),
 			ServiceSocketPath: viper.GetString(socketPathFlagName),
 			SyncServicePort:   viper.GetUint16(syncPortFlagName),
-			WithSyncService:   viper.GetBool(syncEnabledFlagName),
 			SyncProviders:     syncProviders,
 		})
 		if err != nil {

flagd/pkg/runtime/from_config.go

@@ -30,7 +30,6 @@ type Config struct {
 	ServicePort       uint16
 	ServiceSocketPath string
 	SyncServicePort   uint16
-	WithSyncService   bool
 
 	SyncProviders []sync.SourceConfig
 	CORS          []string
@@ -84,17 +83,14 @@ func FromConfig(logger *logger.Logger, version string, config Config) (*Runtime,
 		recorder)
 
 	// flag sync service
-	var flagSyncService flagsync.ISyncService = &flagsync.NoopSyncService{}
-	if config.WithSyncService {
-		flagSyncService, err = flagsync.NewSyncService(flagsync.SvcConfigurations{
-			Logger:  logger.WithFields(zap.String("component", "FlagSyncService")),
-			Port:    config.SyncServicePort,
-			Sources: sources,
-			Store:   s,
-		})
-		if err != nil {
-			return nil, fmt.Errorf("error creating sync service: %w", err)
-		}
+	flagSyncService, err := flagsync.NewSyncService(flagsync.SvcConfigurations{
+		Logger:  logger.WithFields(zap.String("component", "FlagSyncService")),
+		Port:    config.SyncServicePort,
+		Sources: sources,
+		Store:   s,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("error creating sync service: %w", err)
 	}
 
 	// build sync providers

flagd/pkg/service/flag-sync/sync_service.go

@@ -149,16 +149,3 @@ func (t *syncTracker) trackAndUpdate(source string) {
 		close(t.doneChan)
 	}
 }
-
-// NoopSyncService as a filler implementation of the sync service.
-// This can be used as a default implementation and avoid unnecessary null checks or service enabled checks in runtime.
-type NoopSyncService struct{}
-
-func (n *NoopSyncService) Start(context.Context) error {
-	// NOOP
-	return nil
-}
-
-func (n *NoopSyncService) Emit(bool, string) {
-	// NOOP
-}