Remove global config watcher (#8080)

* remove global config watcher

* keep config watcher disabled for tests

* compile fix

* fix resource leak

6 files changed, 103 insertions, 53 deletions

diff --git a/app/admin.go b/app/admin.go
index e46d9073c..e7d1eb9ed 100644
--- a/app/admin.go
+++ b/app/admin.go
@@ -173,13 +173,13 @@ func (a *App) SaveConfig(cfg *model.Config, sendConfigChangeClusterMessage bool)
 		return model.NewAppError("saveConfig", "ent.cluster.save_config.error", nil, "", http.StatusForbidden)
 	}
 
-	utils.DisableConfigWatch()
+	a.DisableConfigWatch()
 	a.UpdateConfig(func(update *model.Config) {
 		*update = *cfg
 	})
 	a.PersistConfig()
 	a.ReloadConfig()
-	utils.EnableConfigWatch()
+	a.EnableConfigWatch()
 
 	if a.Metrics != nil {
 		if *a.Config().MetricsSettings.Enable {
diff --git a/app/app.go b/app/app.go
index 8aa894b9b..561942019 100644
--- a/app/app.go
+++ b/app/app.go
@@ -4,19 +4,16 @@
 package app
 
 import (
-	"crypto/md5"
-	"encoding/json"
-	"fmt"
 	"html/template"
 	"net"
 	"net/http"
-	"runtime/debug"
 	"strings"
 	"sync"
 	"sync/atomic"
 
 	l4g "github.com/alecthomas/log4go"
 	"github.com/gorilla/mux"
+	"github.com/pkg/errors"
 
 	"github.com/mattermost/mattermost-server/einterfaces"
 	ejobs "github.com/mattermost/mattermost-server/einterfaces/jobs"
@@ -65,6 +62,8 @@ type App struct {
 	roles               map[string]*model.Role
 	configListenerId    string
 	licenseListenerId   string
+	disableConfigWatch  bool
+	configWatcher       *utils.ConfigWatcher
 
 	pluginCommands     []*PluginCommand
 	pluginCommandsLock sync.RWMutex
@@ -78,7 +77,7 @@ var appCount = 0
 
 // New creates a new App. You must call Shutdown when you're done with it.
 // XXX: For now, only one at a time is allowed as some resources are still shared.
-func New(options ...Option) *App {
+func New(options ...Option) (*App, error) {
 	appCount++
 	if appCount > 1 {
 		panic("Only one App should exist at a time. Did you forget to call Shutdown()?")
@@ -99,11 +98,16 @@ func New(options ...Option) *App {
 	}
 
 	if utils.T == nil {
-		utils.TranslationsPreInit()
+		if err := utils.TranslationsPreInit(); err != nil {
+			return nil, errors.Wrapf(err, "unable to load Mattermost translation files")
+		}
 	}
 	model.AppErrorInit(utils.T)
 	utils.LoadGlobalConfig(app.configFile)
-	utils.InitTranslations(utils.Cfg.LocalizationSettings)
+	app.EnableConfigWatch()
+	if err := utils.InitTranslations(utils.Cfg.LocalizationSettings); err != nil {
+		return nil, errors.Wrapf(err, "unable to load Mattermost translation files")
+	}
 
 	app.configListenerId = utils.AddConfigListener(func(_, _ *model.Config) {
 		app.configOrLicenseListener()
@@ -142,7 +146,7 @@ func New(options ...Option) *App {
 		handlers: make(map[string]webSocketHandler),
 	}
 
-	return app
+	return app, nil
 }
 
 func (a *App) configOrLicenseListener() {
@@ -171,6 +175,8 @@ func (a *App) Shutdown() {
 	utils.RemoveConfigListener(a.configListenerId)
 	utils.RemoveLicenseListener(a.licenseListenerId)
 	l4g.Info(utils.T("api.server.stop_server.stopped.info"))
+
+	a.DisableConfigWatch()
 }
 
 var accountMigrationInterface func(*App) einterfaces.AccountMigrationInterface
@@ -341,46 +347,6 @@ func (a *App) initJobs() {
 	}
 }
 
-func (a *App) Config() *model.Config {
-	return utils.Cfg
-}
-
-func (a *App) UpdateConfig(f func(*model.Config)) {
-	old := utils.Cfg.Clone()
-	f(utils.Cfg)
-	utils.InvokeGlobalConfigListeners(old, utils.Cfg)
-}
-
-func (a *App) PersistConfig() {
-	utils.SaveConfig(a.ConfigFileName(), a.Config())
-}
-
-func (a *App) ReloadConfig() {
-	debug.FreeOSMemory()
-	utils.LoadGlobalConfig(a.ConfigFileName())
-
-	// start/restart email batching job if necessary
-	a.InitEmailBatching()
-}
-
-func (a *App) ConfigFileName() string {
-	return utils.CfgFileName
-}
-
-func (a *App) ClientConfig() map[string]string {
-	return a.clientConfig
-}
-
-func (a *App) ClientConfigHash() string {
-	return a.clientConfigHash
-}
-
-func (a *App) regenerateClientConfig() {
-	a.clientConfig = utils.GenerateClientConfig(a.Config(), a.DiagnosticId())
-	clientConfigJSON, _ := json.Marshal(a.clientConfig)
-	a.clientConfigHash = fmt.Sprintf("%x", md5.Sum(clientConfigJSON))
-}
-
 func (a *App) DiagnosticId() string {
 	return a.diagnosticId
 }
diff --git a/app/app_test.go b/app/app_test.go
index 2058ddd79..fd24bdfd7 100644
--- a/app/app_test.go
+++ b/app/app_test.go
@@ -11,6 +11,7 @@ import (
 	l4g "github.com/alecthomas/log4go"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/store/storetest"
@@ -47,7 +48,8 @@ func TestMain(m *testing.M) {
 
 func TestAppRace(t *testing.T) {
 	for i := 0; i < 10; i++ {
-		a := New()
+		a, err := New()
+		require.NoError(t, err)
 		a.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.ListenAddress = ":0" })
 		a.StartServer()
 		a.Shutdown()
diff --git a/app/apptestlib.go b/app/apptestlib.go
index 912433290..1ec45f0fa 100644
--- a/app/apptestlib.go
+++ b/app/apptestlib.go
@@ -57,13 +57,18 @@ func StopTestStore() {
 }
 
 func setupTestHelper(enterprise bool) *TestHelper {
-	var options []Option
+	options := []Option{DisableConfigWatch}
 	if testStore != nil {
 		options = append(options, StoreOverride(testStore))
 	}
 
+	a, err := New(options...)
+	if err != nil {
+		panic(err)
+	}
+
 	th := &TestHelper{
-		App:         New(options...),
+		App:         a,
 		pluginHooks: make(map[string]plugin.Hooks),
 	}
 
diff --git a/app/config.go b/app/config.go
new file mode 100644
index 000000000..483804c99
--- /dev/null
+++ b/app/config.go
@@ -0,0 +1,73 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package app
+
+import (
+	"crypto/md5"
+	"encoding/json"
+	"fmt"
+	"runtime/debug"
+
+	l4g "github.com/alecthomas/log4go"
+
+	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/utils"
+)
+
+func (a *App) Config() *model.Config {
+	return utils.Cfg
+}
+
+func (a *App) UpdateConfig(f func(*model.Config)) {
+	old := utils.Cfg.Clone()
+	f(utils.Cfg)
+	utils.InvokeGlobalConfigListeners(old, utils.Cfg)
+}
+
+func (a *App) PersistConfig() {
+	utils.SaveConfig(a.ConfigFileName(), a.Config())
+}
+
+func (a *App) ReloadConfig() {
+	debug.FreeOSMemory()
+	utils.LoadGlobalConfig(a.ConfigFileName())
+
+	// start/restart email batching job if necessary
+	a.InitEmailBatching()
+}
+
+func (a *App) ConfigFileName() string {
+	return utils.CfgFileName
+}
+
+func (a *App) ClientConfig() map[string]string {
+	return a.clientConfig
+}
+
+func (a *App) ClientConfigHash() string {
+	return a.clientConfigHash
+}
+
+func (a *App) EnableConfigWatch() {
+	if a.configWatcher == nil && !a.disableConfigWatch {
+		configWatcher, err := utils.NewConfigWatcher(utils.CfgFileName)
+		if err != nil {
+			l4g.Error(err)
+		}
+		a.configWatcher = configWatcher
+	}
+}
+
+func (a *App) DisableConfigWatch() {
+	if a.configWatcher != nil {
+		a.configWatcher.Close()
+		a.configWatcher = nil
+	}
+}
+
+func (a *App) regenerateClientConfig() {
+	a.clientConfig = utils.GenerateClientConfig(a.Config(), a.DiagnosticId())
+	clientConfigJSON, _ := json.Marshal(a.clientConfig)
+	a.clientConfigHash = fmt.Sprintf("%x", md5.Sum(clientConfigJSON))
+}
diff --git a/app/options.go b/app/options.go
index 9b40806f3..464566024 100644
--- a/app/options.go
+++ b/app/options.go
@@ -35,3 +35,7 @@ func ConfigFile(file string) Option {
 		a.configFile = file
 	}
 }
+
+func DisableConfigWatch(a *App) {
+	a.disableConfigWatch = true
+}