Check license expiration, disable license and notify administrator (#14420)

* Check license expiration and notify administrator

app/server.go

@@ -348,6 +348,9 @@ func NewServer(options ...Option) (*Server, error) {
 		s.Go(func() {
 			runCommandWebhookCleanupJob(s)
 		})
+		s.Go(func() {
+			runLicenseExpirationCheckJob(s)
+		})
 
 		if complianceI := s.Compliance; complianceI != nil {
 			complianceI.StartComplianceDailyJob()
@@ -777,6 +780,13 @@ func runSessionCleanupJob(s *Server) {
 	}, time.Hour*24)
 }
 
+func runLicenseExpirationCheckJob(s *Server) {
+	doLicenseExpirationCheck(s)
+	model.CreateRecurringTask("License Expiration Check", func() {
+		doLicenseExpirationCheck(s)
+	}, time.Hour*24)
+}
+
 func doSecurity(s *Server) {
 	s.DoSecurityUpdateCheck()
 }
@@ -804,6 +814,46 @@ func doSessionCleanup(s *Server) {
 	s.Store.Session().Cleanup(model.GetMillis(), SESSIONS_CLEANUP_BATCH_SIZE)
 }
 
+func doLicenseExpirationCheck(s *Server) {
+	s.FakeApp().LoadLicense()
+	license := s.License()
+
+	if license == nil {
+		mlog.Debug("License cannot be found.")
+		return
+	}
+
+	if !license.IsPastGracePeriod() {
+		mlog.Debug("License is not past the grace period.")
+		return
+	}
+
+	users, err := s.Store.User().GetSystemAdminProfiles()
+	if err != nil {
+		mlog.Error("Failed to get system admins for license expired message from Mattermost.")
+		return
+	}
+
+	//send email to admin(s)
+	for _, user := range users {
+		user := user
+		if user.Email == "" {
+			mlog.Error("Invalid system admin email.", mlog.String("user_email", user.Email))
+			continue
+		}
+
+		mlog.Debug("Sending license expired email.", mlog.String("user_email", user.Email))
+		s.Go(func() {
+			if err := s.FakeApp().SendRemoveExpiredLicenseEmail(user.Email, user.Locale, *s.Config().ServiceSettings.SiteURL, license.Id); err != nil {
+				mlog.Error("Error while sending the license expired email.", mlog.String("user_email", user.Email), mlog.Err(err))
+			}
+		})
+	}
+
+	//remove the license
+	s.FakeApp().RemoveLicense()
+}
+
 func (s *Server) StartSearchEngine() (string, string) {
 	if s.SearchEngine.ElasticsearchEngine != nil && s.SearchEngine.ElasticsearchEngine.IsActive() {
 		s.Go(func() {