MM-25404: Add GetHealthScore metric for the cluster (#14767)

* MM-25404: Add GetHealthScore metric for the cluster

This PR adds the necessary function to the cluster interface
so that they can be called from App code.

* Add mocks

* Remove fakeapp

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/busy_test.go

@@ -124,3 +124,4 @@ func (c *ClusterMock) GetPluginStatuses() (model.PluginStatuses, *model.AppError
 func (c *ClusterMock) ConfigChanged(previousConfig *model.Config, newConfig *model.Config, sendToOtherServer bool) *model.AppError {
 	return nil
 }
+func (c *ClusterMock) HealthScore() int { return 0 }

app/server.go

@@ -1242,6 +1242,10 @@ func (s *Server) TotalWebsocketConnections() int {
 	return int(count)
 }
 
+func (s *Server) ClusterHealthScore() int {
+	return s.Cluster.HealthScore()
+}
+
 func (s *Server) ensureDiagnosticId() {
 	if s.diagnosticId != "" {
 		return

einterfaces/cluster.go

@@ -15,6 +15,10 @@ type ClusterInterface interface {
 	RegisterClusterMessageHandler(event string, crm ClusterMessageHandler)
 	GetClusterId() string
 	IsLeader() bool
+	// HealthScore returns a number which is indicative of how well an instance is meeting
+	// the soft real-time requirements of the protocol. Lower numbers are better,
+	// and zero means "totally healthy".
+	HealthScore() int
 	GetMyClusterInfo() *model.ClusterInfo
 	GetClusterInfos() []*model.ClusterInfo
 	SendClusterMessage(cluster *model.ClusterMessage)

einterfaces/mocks/ClusterInterface.go

@@ -153,6 +153,20 @@ func (_m *ClusterInterface) GetPluginStatuses() (model.PluginStatuses, *model.Ap
 	return r0, r1
 }
 
+// HealthScore provides a mock function with given fields:
+func (_m *ClusterInterface) HealthScore() int {
+	ret := _m.Called()
+
+	var r0 int
+	if rf, ok := ret.Get(0).(func() int); ok {
+		r0 = rf()
+	} else {
+		r0 = ret.Get(0).(int)
+	}
+
+	return r0
+}
+
 // IsLeader provides a mock function with given fields:
 func (_m *ClusterInterface) IsLeader() bool {
 	ret := _m.Called()

testlib/cluster.go

@@ -21,6 +21,10 @@ func (c *FakeClusterInterface) RegisterClusterMessageHandler(event string, crm e
 	c.clusterMessageHandler = crm
 }
 
+func (c *FakeClusterInterface) HealthScore() int {
+	return 0
+}
+
 func (c *FakeClusterInterface) GetClusterId() string { return "" }
 
 func (c *FakeClusterInterface) IsLeader() bool { return false }