Forward migrate action to endpoint

internal/pkg/agent/application/actions/handlers/handler_action_migrate.go

@@ -25,7 +25,9 @@ import (
 const ()
 
 type migrateCoordinator interface {
-	Migrate(_ context.Context, _ *fleetapi.ActionMigrate, _ func(done <-chan struct{}) backoff.Backoff) error
+	actionCoordinator
+
+	Migrate(_ context.Context, _ *fleetapi.ActionMigrate, _ func(done <-chan struct{}) backoff.Backoff, _ func(context.Context, *fleetapi.ActionMigrate) error) error
 	ReExec(callback reexec.ShutdownCallbackFn, argOverrides ...string)
 	Protection() protection.Config
 }
@@ -90,7 +92,7 @@ func (h *Migrate) Handle(ctx context.Context, a fleetapi.Action, ack acker.Acker
 
 	action.Data.EnrollmentToken = enrollmentToken
 
-	if err := h.coord.Migrate(ctx, action, fleetgateway.RequestBackoff); err != nil {
+	if err := h.coord.Migrate(ctx, action, fleetgateway.RequestBackoff, h.notifyComponents); err != nil {
 		// this should not happen, unmanaged agent should not receive the action
 		// defensive coding to avoid misbehavior
 		if errors.Is(err, coordinator.ErrNotManaged) {
@@ -112,6 +114,22 @@ func (h *Migrate) Handle(ctx context.Context, a fleetapi.Action, ack acker.Acker
 	return nil
 }
 
+func (h *Migrate) notifyComponents(ctx context.Context, migrateAction *fleetapi.ActionMigrate) error {
+	state := h.coord.State()
+	ucs := findMatchingUnitsByActionType(state, fleetapi.ActionTypeMigrate)
+	if len(ucs) > 0 {
+		err := notifyUnitsOfProxiedAction(ctx, h.log, migrateAction, ucs, h.coord.PerformAction)
+		if err != nil {
+			return err
+		}
+	} else {
+		// Log and continue
+		h.log.Debugf("No components running for %v action type", fleetapi.ActionTypeMigrate)
+	}
+
+	return nil
+}
+
 func (h *Migrate) ackFailure(ctx context.Context, err error, action *fleetapi.ActionMigrate, acker acker.Acker) {
 	action.Err = err
 

internal/pkg/agent/application/actions/handlers/handler_action_migrate_test.go

@@ -22,6 +22,7 @@ import (
 	"github.com/elastic/elastic-agent/internal/pkg/agent/protection"
 	"github.com/elastic/elastic-agent/internal/pkg/core/backoff"
 	"github.com/elastic/elastic-agent/internal/pkg/fleetapi"
+	"github.com/elastic/elastic-agent/pkg/component"
 	"github.com/elastic/elastic-agent/pkg/core/logger/loggertest"
 	mockinfo "github.com/elastic/elastic-agent/testing/mocks/internal_/pkg/agent/application/info"
 )
@@ -38,7 +39,7 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: nil})
 
@@ -77,7 +78,8 @@ func TestActionMigratelHandler(t *testing.T) {
 				ack.On("Commit", t.Context()).Return(nil)
 
 				coord := &fakeMigrateCoordinator{}
-				coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+				coord.On("State").Return(coordinator.State{})
+				coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 				coord.On("ReExec", mock.Anything, mock.Anything)
 				coord.On("Protection").Return(protection.Config{SignatureValidationKey: nil, Enabled: tc.protectionEnabled})
 
@@ -114,7 +116,8 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+		coord.On("State").Return(coordinator.State{})
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: nil})
 
@@ -163,7 +166,8 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+		coord.On("State").Return(coordinator.State{})
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: signatureValidationKey})
 
@@ -199,7 +203,7 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: signatureValidationKey})
 
@@ -248,7 +252,8 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+		coord.On("State").Return(coordinator.State{})
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: nil})
 
@@ -300,7 +305,7 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(nil)
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(nil)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: signatureValidationKey})
 
@@ -322,7 +327,8 @@ func TestActionMigratelHandler(t *testing.T) {
 		ack.On("Commit", t.Context()).Return(nil)
 
 		coord := &fakeMigrateCoordinator{}
-		coord.On("Migrate", mock.Anything, mock.Anything).Return(coordinator.ErrFleetServer)
+		coord.On("State").Return(coordinator.State{})
+		coord.On("Migrate", mock.Anything, mock.Anything, mock.Anything, mock.Anything).Return(coordinator.ErrFleetServer)
 		coord.On("ReExec", mock.Anything, mock.Anything)
 		coord.On("Protection").Return(protection.Config{SignatureValidationKey: nil})
 
@@ -343,11 +349,21 @@ type fakeMigrateCoordinator struct {
 	mock.Mock
 }
 
-func (f *fakeMigrateCoordinator) Migrate(ctx context.Context, a *fleetapi.ActionMigrate, _ func(done <-chan struct{}) backoff.Backoff) error {
-	args := f.Called(ctx, a)
+func (f *fakeMigrateCoordinator) Migrate(ctx context.Context, a *fleetapi.ActionMigrate, b func(done <-chan struct{}) backoff.Backoff, n func(context.Context, *fleetapi.ActionMigrate) error) error {
+	args := f.Called(ctx, a, b, n)
 	return args.Error(0)
 }
 
+func (f *fakeMigrateCoordinator) State() coordinator.State {
+	args := f.Called()
+	return args.Get(0).(coordinator.State)
+}
+
+func (f *fakeMigrateCoordinator) PerformAction(ctx context.Context, comp component.Component, unit component.Unit, name string, params map[string]interface{}) (map[string]interface{}, error) {
+	args := f.Called(ctx, comp, unit, name, params)
+	return args.Get(0).(map[string]interface{}), args.Error(1)
+}
+
 func (f *fakeMigrateCoordinator) ReExec(callback reexec.ShutdownCallbackFn, argOverrides ...string) {
 	f.Called(callback, argOverrides)
 }

internal/pkg/agent/application/coordinator/coordinator.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -361,6 +362,11 @@ type Coordinator struct {
 
 	// Abstraction for diagnostics AddSecretMarkers function for testability
 	secretMarkerFunc func(*logger.Logger, *config.Config) error
+
+	// migrationProgressWg is used to block processing of incoming policies after enroll is done
+	// incomming policies are blocked until we reboot so components receiving proxied MIGRATE action
+	// are not confused
+	migrationProgressWg sync.WaitGroup
 }
 
 // The channels Coordinator reads to receive updates from the various managers.
@@ -596,7 +602,12 @@ func (c *Coordinator) ReExec(callback reexec.ShutdownCallbackFn, argOverrides ..
 
 // Migrate migrates agent to a new cluster and ACKs success to the old one.
 // In case of failure no ack is performed and error is returned.
-func (c *Coordinator) Migrate(ctx context.Context, action *fleetapi.ActionMigrate, backoffFactory func(done <-chan struct{}) backoff.Backoff) error {
+func (c *Coordinator) Migrate(
+	ctx context.Context,
+	action *fleetapi.ActionMigrate,
+	backoffFactory func(done <-chan struct{}) backoff.Backoff,
+	notifyFn func(context.Context, *fleetapi.ActionMigrate) error,
+) error {
 	if !c.isManaged {
 		return ErrNotManaged
 	}
@@ -666,6 +677,24 @@ func (c *Coordinator) Migrate(ctx context.Context, action *fleetapi.ActionMigrat
 		return errors.Join(fmt.Errorf("failed to enroll: %w", err), restoreErr)
 	}
 
+	// lock processing of new config before notifying components
+	// hold lock until notification failure or reexec
+	c.migrationProgressWg.Add(1)
+	if notifyFn != nil {
+		// notify before completing migration
+		// components such endpoint are crucial to work even though it's on stale cluster
+		// error on component side is returned as part of Action response
+		if err := notifyFn(ctx, action); err != nil {
+			restoreErr := RestoreConfig()
+
+			// in case of failure no need to lock processing
+			// safe to forward policy from source cluster
+			c.migrationProgressWg.Done()
+
+			return errors.Join(fmt.Errorf("failed to notify components: %w", err), restoreErr)
+		}
+	}
+
 	// ACK success to source fleet server
 	if err := c.ackMigration(ctx, action, c.fleetAcker); err != nil {
 		c.logger.Warnf("failed to ACK success: %v", err)
@@ -677,23 +706,30 @@ func (c *Coordinator) Migrate(ctx context.Context, action *fleetapi.ActionMigrat
 		return fmt.Errorf("failed to clean backup config: %w", err)
 	}
 
+	c.bestEffortUnenroll(ctx, originalOptions)
+
+	return nil
+}
+
+func (c *Coordinator) bestEffortUnenroll(ctx context.Context, originalOptions enroll.EnrollOptions) {
 	originalRemoteConfig, err := originalOptions.RemoteConfig(false)
 	if err != nil {
-		return fmt.Errorf("failed to construct original remote config: %w", err)
+		c.logger.Warnf("failed to construct original remote config: %v", err)
+		return
 	}
 
 	originalClient, err := fleetapiClient.NewAuthWithConfig(
 		c.logger, originalOptions.EnrollAPIKey, originalRemoteConfig)
 	if err != nil {
-		return fmt.Errorf("failed to create original fleet client: %w", err)
+		c.logger.Warnf("failed to create original fleet client: %v", err)
+		return
 	}
 
 	// Best effort: call unenroll on source cluster once done
 	if err := c.unenroll(ctx, originalClient); err != nil {
 		c.logger.Warnf("failed to unenroll from original cluster: %v", err)
+		return
 	}
-
-	return nil
 }
 
 type upgradeOpts struct {
@@ -1532,6 +1568,8 @@ func (c *Coordinator) runLoopIteration(ctx context.Context) {
 
 // Always called on the main Coordinator goroutine.
 func (c *Coordinator) processConfig(ctx context.Context, cfg *config.Config) (err error) {
+	c.migrationProgressWg.Wait()
+
 	if c.otelMgr != nil {
 		c.otelCfg = cfg.OTel
 	}