[service/extensions] enforce order of start and shutdown of extension…

…s according to configuration

.chloggen/extension-lifecycle-order.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: service/extensions
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Implement strict ordering of startup, shutdown and notifications to extensions.
+
+# One or more tracking issues or pull requests related to the change
+issues: [8732]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

service/extensions/extensions.go

@@ -23,18 +23,20 @@ const zExtensionName = "zextensionname"
 
 // Extensions is a map of extensions created from extension configs.
 type Extensions struct {
-	telemetry   servicetelemetry.TelemetrySettings
-	extMap      map[component.ID]extension.Extension
-	instanceIDs map[component.ID]*component.InstanceID
+	telemetry    servicetelemetry.TelemetrySettings
+	extensionIDs []component.ID
+	extMap       map[component.ID]extension.Extension
+	instanceIDs  map[component.ID]*component.InstanceID
 }
 
 // Start starts all extensions.
 func (bes *Extensions) Start(ctx context.Context, host component.Host) error {
 	bes.telemetry.Logger.Info("Starting extensions...")
-	for extID, ext := range bes.extMap {
+	for _, extID := range bes.extensionIDs {
 		extLogger := components.ExtensionLogger(bes.telemetry.Logger, extID)
 		extLogger.Info("Extension is starting...")
 		instanceID := bes.instanceIDs[extID]
+		ext := bes.extMap[extID]
 		_ = bes.telemetry.ReportComponentStatus(instanceID, component.NewStatusEvent(component.StatusStarting))
 		if err := ext.Start(ctx, components.NewHostWrapper(host, extLogger)); err != nil {
 			_ = bes.telemetry.ReportComponentStatus(instanceID, component.NewPermanentErrorEvent(err))
@@ -49,8 +51,9 @@ func (bes *Extensions) Start(ctx context.Context, host component.Host) error {
 func (bes *Extensions) Shutdown(ctx context.Context) error {
 	bes.telemetry.Logger.Info("Stopping extensions...")
 	var errs error
-	for extID, ext := range bes.extMap {
+	for _, extID := range bes.extensionIDs {
 		instanceID := bes.instanceIDs[extID]
+		ext := bes.extMap[extID]
 		_ = bes.telemetry.ReportComponentStatus(instanceID, component.NewStatusEvent(component.StatusStopping))
 		if err := ext.Shutdown(ctx); err != nil {
 			_ = bes.telemetry.ReportComponentStatus(instanceID, component.NewPermanentErrorEvent(err))
@@ -64,7 +67,8 @@ func (bes *Extensions) Shutdown(ctx context.Context) error {
 }
 
 func (bes *Extensions) NotifyPipelineReady() error {
-	for extID, ext := range bes.extMap {
+	for _, extID := range bes.extensionIDs {
+		ext := bes.extMap[extID]
 		if pw, ok := ext.(extension.PipelineWatcher); ok {
 			if err := pw.Ready(); err != nil {
 				return fmt.Errorf("failed to notify extension %q: %w", extID, err)
@@ -77,7 +81,8 @@ func (bes *Extensions) NotifyPipelineReady() error {
 func (bes *Extensions) NotifyPipelineNotReady() error {
 	// Notify extensions in reverse order.
 	var errs error
-	for _, ext := range bes.extMap {
+	for _, extID := range bes.extensionIDs {
+		ext := bes.extMap[extID]
 		if pw, ok := ext.(extension.PipelineWatcher); ok {
 			errs = multierr.Append(errs, pw.NotReady())
 		}
@@ -87,7 +92,8 @@ func (bes *Extensions) NotifyPipelineNotReady() error {
 
 func (bes *Extensions) NotifyConfig(ctx context.Context, conf *confmap.Conf) error {
 	var errs error
-	for _, ext := range bes.extMap {
+	for _, extID := range bes.extensionIDs {
+		ext := bes.extMap[extID]
 		if cw, ok := ext.(extension.ConfigWatcher); ok {
 			clonedConf := confmap.NewFromStringMap(conf.ToStringMap())
 			errs = multierr.Append(errs, cw.NotifyConfig(ctx, clonedConf))
@@ -97,7 +103,8 @@ func (bes *Extensions) NotifyConfig(ctx context.Context, conf *confmap.Conf) err
 }
 
 func (bes *Extensions) NotifyComponentStatusChange(source *component.InstanceID, event *component.StatusEvent) {
-	for _, ext := range bes.extMap {
+	for _, extID := range bes.extensionIDs {
+		ext := bes.extMap[extID]
 		if sw, ok := ext.(extension.StatusWatcher); ok {
 			sw.ComponentStatusChanged(source, event)
 		}
@@ -120,7 +127,7 @@ func (bes *Extensions) HandleZPages(w http.ResponseWriter, r *http.Request) {
 	data := zpages.SummaryExtensionsTableData{}
 
 	data.Rows = make([]zpages.SummaryExtensionsTableRowData, 0, len(bes.extMap))
-	for id := range bes.extMap {
+	for _, id := range bes.extensionIDs {
 		row := zpages.SummaryExtensionsTableRowData{FullName: id.String()}
 		data.Rows = append(data.Rows, row)
 	}
@@ -150,9 +157,10 @@ type Settings struct {
 // New creates a new Extensions from Config.
 func New(ctx context.Context, set Settings, cfg Config) (*Extensions, error) {
 	exts := &Extensions{
-		telemetry:   set.Telemetry,
-		extMap:      make(map[component.ID]extension.Extension),
-		instanceIDs: make(map[component.ID]*component.InstanceID),
+		telemetry:    set.Telemetry,
+		extMap:       make(map[component.ID]extension.Extension),
+		instanceIDs:  make(map[component.ID]*component.InstanceID),
+		extensionIDs: make([]component.ID, 0, len(cfg)),
 	}
 	for _, extID := range cfg {
 		instanceID := &component.InstanceID{
@@ -178,6 +186,7 @@ func New(ctx context.Context, set Settings, cfg Config) (*Extensions, error) {
 
 		exts.extMap[extID] = ext
 		exts.instanceIDs[extID] = instanceID
+		exts.extensionIDs = append(exts.extensionIDs, extID)
 	}
 
 	return exts, nil

service/extensions/extensions_test.go

@@ -93,6 +93,44 @@ func TestBuildExtensions(t *testing.T) {
 	}
 }
 
+func TestOrdering(t *testing.T) {
+	var startOrder []string
+	var shutdownOrder []string
+
+	recordingExtensionFactory := newRecordingExtensionFactory(func(set extension.CreateSettings, host component.Host) error {
+		startOrder = append(startOrder, set.ID.String())
+		return nil
+	}, func(set extension.CreateSettings) error {
+		shutdownOrder = append(shutdownOrder, set.ID.String())
+		return nil
+	})
+
+	exts, err := New(context.Background(), Settings{
+		Telemetry: servicetelemetry.NewNopTelemetrySettings(),
+		BuildInfo: component.NewDefaultBuildInfo(),
+		Extensions: extension.NewBuilder(
+			map[component.ID]component.Config{
+				component.NewID(recordingExtensionFactory.Type()):                struct{}{},
+				component.NewIDWithName(recordingExtensionFactory.Type(), "foo"): struct{}{},
+				component.NewIDWithName(recordingExtensionFactory.Type(), "bar"): struct{}{},
+			},
+			map[component.Type]extension.Factory{
+				recordingExtensionFactory.Type(): recordingExtensionFactory,
+			}),
+	}, Config{
+		component.NewID(recordingExtensionFactory.Type()),
+		component.NewIDWithName(recordingExtensionFactory.Type(), "foo"),
+		component.NewIDWithName(recordingExtensionFactory.Type(), "bar"),
+	})
+	require.NoError(t, err)
+	err = exts.Start(context.Background(), componenttest.NewNopHost())
+	require.NoError(t, err)
+	require.Equal(t, []string{"recording", "recording/foo", "recording/bar"}, startOrder)
+	err = exts.Shutdown(context.Background())
+	require.NoError(t, err)
+	require.Equal(t, []string{"recording", "recording/foo", "recording/bar"}, shutdownOrder)
+}
+
 func TestNotifyConfig(t *testing.T) {
 	notificationError := errors.New("Error processing config")
 	nopExtensionFactory := extensiontest.NewNopFactory()
@@ -362,3 +400,34 @@ func newStatusTestExtensionFactory(name component.Type, startErr, shutdownErr er
 		component.StabilityLevelDevelopment,
 	)
 }
+
+func newRecordingExtensionFactory(startCallback func(set extension.CreateSettings, host component.Host) error, shutdownCallback func(set extension.CreateSettings) error) extension.Factory {
+	return extension.NewFactory(
+		"recording",
+		func() component.Config {
+			return &struct{}{}
+		},
+		func(ctx context.Context, set extension.CreateSettings, extension component.Config) (extension.Extension, error) {
+			return &recordingExtension{
+				createSettings:   set,
+				startCallback:    startCallback,
+				shutdownCallback: shutdownCallback,
+			}, nil
+		},
+		component.StabilityLevelDevelopment,
+	)
+}
+
+type recordingExtension struct {
+	startCallback    func(set extension.CreateSettings, host component.Host) error
+	shutdownCallback func(set extension.CreateSettings) error
+	createSettings   extension.CreateSettings
+}
+
+func (ext *recordingExtension) Start(_ context.Context, host component.Host) error {
+	return ext.startCallback(ext.createSettings, host)
+}
+
+func (ext *recordingExtension) Shutdown(_ context.Context) error {
+	return ext.shutdownCallback(ext.createSettings)
+}