Migrate cluster to use Server struct directly. (#10101)

app/cluster.go

@@ -4,28 +4,27 @@
 package app
 
 import (
-	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 )
 
 // Registers a given function to be called when the cluster leader may have changed. Returns a unique ID for the
 // listener which can later be used to remove it. If clustering is not enabled in this build, the callback will never
 // be called.
-func (a *App) AddClusterLeaderChangedListener(listener func()) string {
+func (s *Server) AddClusterLeaderChangedListener(listener func()) string {
 	id := model.NewId()
-	a.Srv.clusterLeaderListeners.Store(id, listener)
+	s.clusterLeaderListeners.Store(id, listener)
 	return id
 }
 
 // Removes a listener function by the unique ID returned when AddConfigListener was called
-func (a *App) RemoveClusterLeaderChangedListener(id string) {
-	a.Srv.clusterLeaderListeners.Delete(id)
+func (s *Server) RemoveClusterLeaderChangedListener(id string) {
+	s.clusterLeaderListeners.Delete(id)
 }
 
-func (a *App) InvokeClusterLeaderChangedListeners() {
-	mlog.Info("Cluster leader changed. Invoking ClusterLeaderChanged listeners.")
-	a.Srv.Go(func() {
-		a.Srv.clusterLeaderListeners.Range(func(_, listener interface{}) bool {
+func (s *Server) InvokeClusterLeaderChangedListeners() {
+	s.Log.Info("Cluster leader changed. Invoking ClusterLeaderChanged listeners.")
+	s.Go(func() {
+		s.clusterLeaderListeners.Range(func(_, listener interface{}) bool {
 			listener.(func())()
 			return true
 		})

app/enterprise.go

@@ -17,9 +17,9 @@ func RegisterAccountMigrationInterface(f func(*App) einterfaces.AccountMigration
 	accountMigrationInterface = f
 }
 
-var clusterInterface func(*App) einterfaces.ClusterInterface
+var clusterInterface func(*Server) einterfaces.ClusterInterface
 
-func RegisterClusterInterface(f func(*App) einterfaces.ClusterInterface) {
+func RegisterClusterInterface(f func(*Server) einterfaces.ClusterInterface) {
 	clusterInterface = f
 }
 
@@ -135,6 +135,6 @@ func (s *Server) initEnterprise() {
 		s.DataRetention = dataRetentionInterface(s.FakeApp())
 	}
 	if clusterInterface != nil {
-		s.Cluster = clusterInterface(s.FakeApp())
+		s.Cluster = clusterInterface(s)
 	}
 }

app/options.go

@@ -40,6 +40,18 @@ func RunJobs(s *Server) {
 	s.runjobs = true
 }
 
+func JoinCluster(s *Server) {
+	s.joinCluster = true
+}
+
+func StartMetrics(s *Server) {
+	s.startMetrics = true
+}
+
+func StartElasticsearch(s *Server) {
+	s.startElasticsearch = true
+}
+
 func DisableConfigWatch(s *Server) {
 	s.disableConfigWatch = true
 }

app/server.go

@@ -112,6 +112,10 @@ type Server struct {
 
 	Log *mlog.Logger
 
+	joinCluster        bool
+	startMetrics       bool
+	startElasticsearch bool
+
 	AccountMigration einterfaces.AccountMigrationInterface
 	Cluster          einterfaces.ClusterInterface
 	Compliance       einterfaces.ComplianceInterface
@@ -214,16 +218,16 @@ func NewServer(options ...Option) (*Server, error) {
 		mlog.Error(fmt.Sprint("Error to reset the server status.", result.Err.Error()))
 	}
 
-	if s.Cluster != nil {
+	if s.joinCluster && s.Cluster != nil {
 		s.FakeApp().RegisterAllClusterMessageHandlers()
 		s.Cluster.StartInterNodeCommunication()
 	}
 
-	if s.Metrics != nil {
+	if s.startMetrics && s.Metrics != nil {
 		s.Metrics.StartServer()
 	}
 
-	if s.Elasticsearch != nil {
+	if s.startElasticsearch && s.Elasticsearch != nil {
 		s.StartElasticsearch()
 	}
 

app/server_app_adapters.go

@@ -86,7 +86,7 @@ func (s *Server) RunOldAppInitalization() error {
 	a.EnsureDiagnosticId()
 	a.regenerateClientConfig()
 
-	a.Srv.clusterLeaderListenerId = a.AddClusterLeaderChangedListener(func() {
+	a.Srv.clusterLeaderListenerId = a.Srv.AddClusterLeaderChangedListener(func() {
 		mlog.Info("Cluster leader changed. Determining if job schedulers should be running:", mlog.Bool("isLeader", a.IsLeader()))
 		if a.Srv.Jobs != nil {
 			a.Srv.Jobs.Schedulers.HandleClusterLeaderChange(a.IsLeader())
@@ -156,7 +156,7 @@ func (s *Server) RunOldAppShutdown() {
 	a.StopPushNotificationsHubWorkers()
 	a.ShutDownPlugins()
 	a.RemoveLicenseListener(s.licenseListenerId)
-	a.RemoveClusterLeaderChangedListener(s.clusterLeaderListenerId)
+	s.RemoveClusterLeaderChangedListener(s.clusterLeaderListenerId)
 }
 
 // A temporary bridge to deal with cases where the code is so tighly coupled that

cmd/mattermost/commands/server.go

@@ -47,6 +47,7 @@ func runServer(configFileLocation string, disableConfigWatch bool, usedPlatform
 	options := []app.Option{
 		app.ConfigFile(configFileLocation),
 		app.RunJobs,
+		app.JoinCluster,
 	}
 	if disableConfigWatch {
 		options = append(options, app.DisableConfigWatch)