[8.4](backport #1285) Expand status reporter/controller interfaces to allow local reporters (#1305)

* Expand status reporter/controller interfaces to allow local reporters (#1285)

* Expand status reporter/controller interfaces to allow local reporters

Add a local reporter map to the status controller. These reporters are
not used when updating status with fleet-server, they are only used to
gather local state information - specifically if the agent is degraded
because checkin with fleet-server has failed. This bypasses the bug that
was introduced with the liveness endpoint where the agent could checkin
(to fleet-server) with a degraded status because a previous checkin
failed. Local reporters are used to generate a separate status. This
status is used in the liveness endpoint.

* fix linter

(cherry picked from commit 717708a)

# Conflicts:
#	internal/pkg/core/status/reporter.go

* Fix merge conflict

Co-authored-by: Michel Laterman <82832767+michel-laterman@users.noreply.github.com>
Co-authored-by: michel-laterman <michel.laterman@elastic.co>

Author: mergify[bot]

CHANGELOG.next.asciidoc

@@ -116,6 +116,7 @@
 - Use at least warning level for all status logs {pull}1218[1218]
 - Remove fleet event reporter and events from checkin body. {issue}993[993]
 - Fix unintended reset of source URI when downloading components {pull}1252[1252]
+- Create separate status reporter for local only events so that degraded fleet-checkins no longer affect health on successful fleet-checkins. {issue}1157[1157] {pull}1285[1285]
 
 ==== New features
 

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

@@ -88,6 +88,7 @@ type fleetGateway struct {
 	checkinFailCounter int
 	statusController   status.Controller
 	statusReporter     status.Reporter
+	localReporter      status.Reporter
 	stateStore         stateStore
 	queue              actionQueue
 }
@@ -156,6 +157,7 @@ func newFleetGatewayWithScheduler(
 		done:             done,
 		acker:            acker,
 		statusReporter:   statusController.RegisterComponent("gateway"),
+		localReporter:    statusController.RegisterLocalComponent("gateway-checkin"),
 		statusController: statusController,
 		stateStore:       stateStore,
 		queue:            queue,
@@ -208,6 +210,7 @@ func (f *fleetGateway) worker() {
 				f.statusReporter.Update(state.Failed, errMsg, nil)
 			} else {
 				f.statusReporter.Update(state.Healthy, "", nil)
+				f.localReporter.Update(state.Healthy, "", nil) // we don't need to specifically set the local reporter to failed above, but it needs to be reset to healthy if a checking succeeds
 			}
 
 		case <-f.bgContext.Done():
@@ -291,12 +294,11 @@ func (f *fleetGateway) doExecute() (*fleetapi.CheckinResponse, error) {
 				)
 
 				f.log.Error(err)
+				f.localReporter.Update(state.Failed, err.Error(), nil)
 				return nil, err
 			}
 			if f.checkinFailCounter > 1 {
-				// do not update status reporter with failure
-				// status reporter would report connection failure on first successful connection, leading to
-				// stale result for certain period causing slight confusion.
+				f.localReporter.Update(state.Degraded, fmt.Sprintf("checkin failed: %v", err), nil)
 				f.log.Errorf("checking number %d failed: %s", f.checkinFailCounter, err.Error())
 			}
 			continue
@@ -386,6 +388,7 @@ func (f *fleetGateway) stop() {
 	f.log.Info("Fleet gateway is stopping")
 	defer f.scheduler.Stop()
 	f.statusReporter.Unregister()
+	f.localReporter.Unregister()
 	close(f.done)
 	f.wg.Wait()
 }

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

@@ -25,6 +25,7 @@ import (
 	"github.com/elastic/elastic-agent/internal/pkg/agent/application/paths"
 	"github.com/elastic/elastic-agent/internal/pkg/agent/storage"
 	"github.com/elastic/elastic-agent/internal/pkg/agent/storage/store"
+	"github.com/elastic/elastic-agent/internal/pkg/core/state"
 	"github.com/elastic/elastic-agent/internal/pkg/fleetapi"
 	noopacker "github.com/elastic/elastic-agent/internal/pkg/fleetapi/acker/noop"
 	"github.com/elastic/elastic-agent/internal/pkg/scheduler"
@@ -703,12 +704,18 @@ func TestRetriesOnFailures(t *testing.T) {
 		queue.On("DequeueActions").Return([]fleetapi.Action{})
 		queue.On("Actions").Return([]fleetapi.Action{})
 
+		localReporter := &testutils.MockReporter{}
+		localReporter.On("Update", state.Degraded, mock.Anything, mock.Anything).Times(2)
+		localReporter.On("Update", mock.Anything, mock.Anything, mock.Anything).Maybe()
+		localReporter.On("Unregister").Maybe()
+
 		fleetReporter := &testutils.MockReporter{}
 		fleetReporter.On("Update", mock.Anything, mock.Anything, mock.Anything).Maybe()
 		fleetReporter.On("Unregister").Maybe()
 
 		statusController := &testutils.MockController{}
 		statusController.On("RegisterComponent", "gateway").Return(fleetReporter).Once()
+		statusController.On("RegisterLocalComponent", "gateway-checkin").Return(localReporter).Once()
 		statusController.On("StatusString").Return("string")
 
 		gateway, err := newFleetGatewayWithScheduler(
@@ -767,6 +774,7 @@ func TestRetriesOnFailures(t *testing.T) {
 		waitFn()
 		statusController.AssertExpectations(t)
 		fleetReporter.AssertExpectations(t)
+		localReporter.AssertExpectations(t)
 	})
 
 	t.Run("The retry loop is interruptible",

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

@@ -13,13 +13,17 @@ import (
 
 type noopController struct{}
 
-func (*noopController) SetAgentID(_ string)                        {}
-func (*noopController) RegisterComponent(_ string) status.Reporter { return &noopReporter{} }
+func (*noopController) SetAgentID(_ string)                             {}
+func (*noopController) RegisterComponent(_ string) status.Reporter      { return &noopReporter{} }
+func (*noopController) RegisterLocalComponent(_ string) status.Reporter { return &noopReporter{} }
 func (*noopController) RegisterComponentWithPersistance(_ string, _ bool) status.Reporter {
 	return &noopReporter{}
 }
-func (*noopController) RegisterApp(_ string, _ string) status.Reporter   { return &noopReporter{} }
-func (*noopController) Status() status.AgentStatus                       { return status.AgentStatus{Status: status.Healthy} }
+func (*noopController) RegisterApp(_ string, _ string) status.Reporter { return &noopReporter{} }
+func (*noopController) Status() status.AgentStatus                     { return status.AgentStatus{Status: status.Healthy} }
+func (*noopController) LocalStatus() status.AgentStatus {
+	return status.AgentStatus{Status: status.Healthy}
+}
 func (*noopController) StatusCode() status.AgentStatusCode               { return status.Healthy }
 func (*noopController) UpdateStateID(_ string)                           {}
 func (*noopController) StatusString() string                             { return "online" }

internal/pkg/core/status/handler.go

@@ -19,10 +19,11 @@ type LivenessResponse struct {
 }
 
 // ServeHTTP is an HTTP Handler for the status controller.
+// It uses the local agent status so it is able to report a degraded state if the fleet-server checkin has issues.
 // Respose code is 200 for a healthy agent, and 503 otherwise.
 // Response body is a JSON object that contains the agent ID, status, message, and the last status update time.
 func (r *controller) ServeHTTP(wr http.ResponseWriter, req *http.Request) {
-	s := r.Status()
+	s := r.LocalStatus()
 	lr := LivenessResponse{
 		ID:         r.agentID,
 		Status:     s.Status.String(),

internal/pkg/core/status/reporter.go

@@ -58,25 +58,31 @@ type AgentStatus struct {
 type Controller interface {
 	SetAgentID(string)
 	RegisterComponent(string) Reporter
+	RegisterLocalComponent(string) Reporter
 	RegisterComponentWithPersistance(string, bool) Reporter
 	RegisterApp(id string, name string) Reporter
 	Status() AgentStatus
+	LocalStatus() AgentStatus
 	StatusCode() AgentStatusCode
 	StatusString() string
 	UpdateStateID(string)
 	ServeHTTP(http.ResponseWriter, *http.Request)
 }
 
 type controller struct {
-	mx           sync.Mutex
-	status       AgentStatusCode
-	message      string
-	updateTime   time.Time
-	reporters    map[string]*reporter
-	appReporters map[string]*reporter
-	log          *logger.Logger
-	stateID      string
-	agentID      string
+	updateTime     time.Time
+	log            *logger.Logger
+	reporters      map[string]*reporter
+	localReporters map[string]*reporter
+	appReporters   map[string]*reporter
+	stateID        string
+	message        string
+	agentID        string
+	status         AgentStatusCode
+	localStatus    AgentStatusCode
+	localMessage   string
+	localTime      time.Time
+	mx             sync.Mutex
 }
 
 // NewController creates a new reporter.
@@ -126,6 +132,28 @@ func (r *controller) UpdateStateID(stateID string) {
 	r.updateStatus()
 }
 
+// RegisterLocalComponent registers new component for local-only status updates.
+func (r *controller) RegisterLocalComponent(componentIdentifier string) Reporter {
+	id := componentIdentifier + "-" + uuid.New().String()[:8]
+	rep := &reporter{
+		name:         componentIdentifier,
+		isRegistered: true,
+		unregisterFunc: func() {
+			r.mx.Lock()
+			delete(r.localReporters, id)
+			r.mx.Unlock()
+		},
+		notifyChangeFunc: r.updateStatus,
+		isPersistent:     false,
+	}
+
+	r.mx.Lock()
+	r.localReporters[id] = rep
+	r.mx.Unlock()
+
+	return rep
+}
+
 // Register registers new component for status updates.
 func (r *controller) RegisterComponent(componentIdentifier string) Reporter {
 	return r.RegisterComponentWithPersistance(componentIdentifier, false)
@@ -199,6 +227,25 @@ func (r *controller) Status() AgentStatus {
 	}
 }
 
+// LocalStatus returns the status from the local registered components if they are different from the agent status.
+// If the agent status is more severe then the local status (failed vs degraded for example) agent status is used.
+// If they are equal (healthy and healthy) agent status is used.
+func (r *controller) LocalStatus() AgentStatus {
+	status := r.Status()
+	r.mx.Lock()
+	defer r.mx.Unlock()
+
+	if r.localStatus > status.Status {
+		return AgentStatus{
+			Status:     r.localStatus,
+			Message:    r.localMessage,
+			UpdateTime: r.localTime,
+		}
+	}
+	return status
+
+}
+
 // StatusCode retrieves current agent status code.
 func (r *controller) StatusCode() AgentStatusCode {
 	r.mx.Lock()
@@ -208,9 +255,23 @@ func (r *controller) StatusCode() AgentStatusCode {
 
 func (r *controller) updateStatus() {
 	status := Healthy
+	lStatus := Healthy
 	message := ""
+	lMessage := ""
 
 	r.mx.Lock()
+	for id, rep := range r.localReporters {
+		s := statusToAgentStatus(rep.status)
+		if s > lStatus {
+			lStatus = s
+			lMessage = fmt.Sprintf("component %s: %s", id, rep.message)
+		}
+		r.log.Debugf("local component '%s' has status '%s'", id, s)
+		if status == Failed {
+			break
+		}
+	}
+
 	for id, rep := range r.reporters {
 		s := statusToAgentStatus(rep.status)
 		if s > status {
@@ -244,6 +305,11 @@ func (r *controller) updateStatus() {
 		r.message = message
 		r.updateTime = time.Now().UTC()
 	}
+	if r.localStatus != lStatus {
+		r.localStatus = lStatus
+		r.localMessage = lMessage
+		r.localTime = time.Now().UTC()
+	}
 
 	r.mx.Unlock()
 

internal/pkg/testutils/status_reporter.go

@@ -25,6 +25,11 @@ func (m *MockController) RegisterComponent(id string) status.Reporter {
 	return args.Get(0).(status.Reporter)
 }
 
+func (m *MockController) RegisterLocalComponent(id string) status.Reporter {
+	args := m.Called(id)
+	return args.Get(0).(status.Reporter)
+}
+
 func (m *MockController) RegisterComponentWithPersistance(id string, b bool) status.Reporter {
 	args := m.Called(id, b)
 	return args.Get(0).(status.Reporter)
@@ -40,6 +45,11 @@ func (m *MockController) Status() status.AgentStatus {
 	return args.Get(0).(status.AgentStatus)
 }
 
+func (m *MockController) LocalStatus() status.AgentStatus {
+	args := m.Called()
+	return args.Get(0).(status.AgentStatus)
+}
+
 func (m *MockController) StatusCode() status.AgentStatusCode {
 	args := m.Called()
 	return args.Get(0).(status.AgentStatusCode)