[fast checkin]: work around the config limitations (#11165)

Author: moukoublen

internal/pkg/agent/application/gateway/fleet/fleet_gateway.go

@@ -100,7 +100,7 @@ func New(
 	acker acker.Acker,
 	stateStore stateStore,
 	stateFetcher StateFetcher,
-	cfg configuration.FleetCheckin,
+	cfg *configuration.FleetCheckin,
 ) (*FleetGateway, error) {
 	scheduler := scheduler.NewPeriodicJitter(defaultGatewaySettings.Duration, defaultGatewaySettings.Jitter)
 	st := defaultGatewaySettings
@@ -615,9 +615,13 @@ func (s *CheckinStateFetcher) FetchState(ctx context.Context) (coordinator.State
 func (s *CheckinStateFetcher) Done()                                     {}
 func (s *CheckinStateFetcher) StartStateWatch(ctx context.Context) error { return nil }
 
-func getBackoffSettings(cfg configuration.FleetCheckin) *backoffSettings {
+func getBackoffSettings(cfg *configuration.FleetCheckin) *backoffSettings {
 	bo := defaultFleetBackoffSettings
 
+	if cfg == nil {
+		return &defaultFleetBackoffSettings
+	}
+
 	if cfg.RequestBackoffInit > 0 {
 		bo.Init = cfg.RequestBackoffInit
 	}

internal/pkg/agent/application/managed_mode.go

@@ -175,7 +175,7 @@ func (m *managedConfigManager) Run(ctx context.Context) error {
 	} else {
 		stateFetcher = fleetgateway.NewCheckinStateFetcher(m.coord.State)
 	}
-	m.log.Infof("running managed config manager with checkin mode: %s", m.cfg.Fleet.Checkin.Mode)
+	m.log.Infof("running managed config manager with checkin mode: %s", m.cfg.Fleet.Checkin.GetMode())
 
 	gateway, err := fleetgateway.New(
 		m.log,

internal/pkg/agent/configuration/fleet.go

@@ -21,7 +21,7 @@ type FleetAgentConfig struct {
 	Client              remote.Config      `config:",inline" yaml:",inline"`
 	Info                *AgentInfo         `config:"agent" yaml:"agent"`
 	Server              *FleetServerConfig `config:"server" yaml:"server,omitempty"`
-	Checkin             FleetCheckin       `config:"checkin" yaml:"checkin,omitempty"`
+	Checkin             *FleetCheckin      `config:"checkin" yaml:"checkin,omitempty"`
 }
 
 // Valid validates the required fields for accessing the API.
@@ -54,13 +54,7 @@ func DefaultFleetAgentConfig() *FleetAgentConfig {
 		Enabled: false,
 		Client:  remote.DefaultClientConfig(),
 		Info:    &AgentInfo{},
-		Checkin: DefaultFleetCheckin(),
-	}
-}
-
-func DefaultFleetCheckin() FleetCheckin {
-	return FleetCheckin{
-		Mode: fleetCheckinModeStandard,
+		Checkin: nil,
 	}
 }
 
@@ -71,10 +65,22 @@ type FleetCheckin struct {
 }
 
 func (f *FleetCheckin) IsModeOnStateChanged() bool {
-	return f.Mode == fleetCheckinModeOnStateChanged
+	return f != nil && f.Mode == fleetCheckinModeOnStateChanged
+}
+
+func (f *FleetCheckin) GetMode() string {
+	if f == nil || f.Mode == "" {
+		return fleetCheckinModeStandard
+	}
+
+	return f.Mode
 }
 
 func (f *FleetCheckin) Validate() error {
+	if f == nil {
+		return nil
+	}
+
 	if f.Mode != "" && f.Mode != fleetCheckinModeStandard && f.Mode != fleetCheckinModeOnStateChanged {
 		return errors.New("checkin.mode must be either 'standard' or 'on_state_change'")
 	}

internal/pkg/config/config_test.go

@@ -131,7 +131,7 @@ func TestCommaParsing(t *testing.T) {
 func dumpToYAML(t *testing.T, out string, in interface{}) {
 	b, err := yaml.Marshal(in)
 	require.NoError(t, err)
-	err = os.WriteFile(out, b, 0600)
+	err = os.WriteFile(out, b, 0o600)
 	require.NoError(t, err)
 }