[MM-32234] Fix config.json getting reset (#16805)

* Add support for read-only config stores * Allow read/write config store for plugin commands that require it
2021-01-28 20:04:17 +01:00
--- a/api4/apitestlib.go
+++ b/api4/apitestlib.go
@@ -96,7 +96,7 @@ func setupTestHelper(dbStore store.Store, searchEngine *searchengine.Broker, ent
 	}
 	memoryStore.Set(memoryConfig)

-	configStore, err := config.NewStoreFromBacking(memoryStore, nil)
+	configStore, err := config.NewStoreFromBacking(memoryStore, nil, false)
 	if err != nil {
 		panic(err)
 	}
--- a/api4/config_test.go
+++ b/api4/config_test.go
@@ -691,11 +691,11 @@ func TestMigrateConfig(t *testing.T) {
 	})

 	th.TestForSystemAdminAndLocal(t, func(t *testing.T, client *model.Client4) {
-		f, err := config.NewStore("from.json", false, nil)
+		f, err := config.NewStore("from.json", false, false, nil)
 		require.NoError(t, err)
 		defer f.RemoveFile("from.json")

-		_, err = config.NewStore("to.json", false, nil)
+		_, err = config.NewStore("to.json", false, false, nil)
 		require.NoError(t, err)
 		defer f.RemoveFile("to.json")

--- a/app/config.go
+++ b/app/config.go
@@ -46,6 +46,9 @@ func (a *App) EnvironmentConfig() map[string]interface{} {
 }

 func (s *Server) UpdateConfig(f func(*model.Config)) {
+	if s.configStore.IsReadOnly() {
+		return
+	}
 	old := s.Config()
 	updated := old.Clone()
 	f(updated)
--- a/app/options.go
+++ b/app/options.go
@@ -43,9 +43,9 @@ func StoreOverride(override interface{}) Option {
 // or a database connection string. It receives as well a set of
 // custom defaults that will be applied for any unset property of the
 // config loaded from the dsn on top of the normal defaults
-func Config(dsn string, watch bool, configDefaults *model.Config) Option {
+func Config(dsn string, watch, readOnly bool, configDefaults *model.Config) Option {
 	return func(s *Server) error {
-		configStore, err := config.NewStore(dsn, watch, configDefaults)
+		configStore, err := config.NewStore(dsn, watch, readOnly, configDefaults)
 		if err != nil {
 			return errors.Wrap(err, "failed to apply Config option")
 		}
--- a/app/server.go
+++ b/app/server.go
@@ -210,7 +210,7 @@ func NewServer(options ...Option) (*Server, error) {
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to load config")
 		}
-		configStore, err := config.NewStoreFromBacking(innerStore, nil)
+		configStore, err := config.NewStoreFromBacking(innerStore, nil, false)
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to load config")
 		}
--- a/app/server_test.go
+++ b/app/server_test.go
@@ -384,7 +384,7 @@ func TestSentry(t *testing.T) {

 		s, err := NewServer(func(server *Server) error {
 			configStore, _ := config.NewFileStore("config.json", true)
-			store, _ := config.NewStoreFromBacking(configStore, nil)
+			store, _ := config.NewStoreFromBacking(configStore, nil, false)
 			server.configStore = store
 			server.UpdateConfig(func(cfg *model.Config) {
 				*cfg.ServiceSettings.ListenAddress = ":0"
@@ -435,7 +435,7 @@ func TestSentry(t *testing.T) {

 		s, err := NewServer(func(server *Server) error {
 			configStore, _ := config.NewFileStore("config.json", true)
-			store, _ := config.NewStoreFromBacking(configStore, nil)
+			store, _ := config.NewStoreFromBacking(configStore, nil, false)
 			server.configStore = store
 			server.UpdateConfig(func(cfg *model.Config) {
 				*cfg.ServiceSettings.ListenAddress = ":0"
--- a/cmd/mattermost/commands/config.go
+++ b/cmd/mattermost/commands/config.go
@@ -145,7 +145,7 @@ func getConfigStore(command *cobra.Command) (*config.Store, error) {
 		return nil, errors.Wrap(err, "failed to initialize i18n")
 	}

-	configStore, err := config.NewStore(getConfigDSN(command, config.GetEnvironment()), false, nil)
+	configStore, err := config.NewStore(getConfigDSN(command, config.GetEnvironment()), false, false, nil)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to initialize config store")
 	}
--- a/cmd/mattermost/commands/config_test.go
+++ b/cmd/mattermost/commands/config_test.go
@@ -543,9 +543,9 @@ func TestConfigMigrate(t *testing.T) {
 	sqlDSN := getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource)
 	fileDSN := "config.json"

-	ds, err := config.NewStore(sqlDSN, false, nil)
+	ds, err := config.NewStore(sqlDSN, false, false, nil)
 	require.NoError(t, err)
-	fs, err := config.NewStore(fileDSN, false, nil)
+	fs, err := config.NewStore(fileDSN, false, false, nil)
 	require.NoError(t, err)

 	defer ds.Close()
--- a/cmd/mattermost/commands/db.go
+++ b/cmd/mattermost/commands/db.go
@@ -57,7 +57,7 @@ func initDbCmdF(command *cobra.Command, _ []string) error {
 		return errors.Wrap(err, "error loading custom configuration defaults")
 	}

-	configStore, err := config.NewStore(getConfigDSN(command, config.GetEnvironment()), false, customDefaults)
+	configStore, err := config.NewStore(getConfigDSN(command, config.GetEnvironment()), false, false, customDefaults)
 	if err != nil {
 		return errors.Wrap(err, "failed to load configuration")
 	}
--- a/cmd/mattermost/commands/init.go
+++ b/cmd/mattermost/commands/init.go
@@ -12,8 +12,8 @@ import (
 	"github.com/mattermost/mattermost-server/v5/utils"
 )

-func InitDBCommandContextCobra(command *cobra.Command) (*app.App, error) {
-	a, err := InitDBCommandContext(getConfigDSN(command, config.GetEnvironment()))
+func initDBCommandContextCobra(command *cobra.Command, readOnlyConfigStore bool) (*app.App, error) {
+	a, err := initDBCommandContext(getConfigDSN(command, config.GetEnvironment()), readOnlyConfigStore)
 	if err != nil {
 		// Returning an error just prints the usage message, so actually panic
 		panic(err)
@@ -25,14 +25,22 @@ func InitDBCommandContextCobra(command *cobra.Command) (*app.App, error) {
 	return a, nil
 }

-func InitDBCommandContext(configDSN string) (*app.App, error) {
+func InitDBCommandContextCobra(command *cobra.Command) (*app.App, error) {
+	return initDBCommandContextCobra(command, true)
+}
+
+func InitDBCommandContextCobraReadWrite(command *cobra.Command) (*app.App, error) {
+	return initDBCommandContextCobra(command, false)
+}
+
+func initDBCommandContext(configDSN string, readOnlyConfigStore bool) (*app.App, error) {
 	if err := utils.TranslationsPreInit(); err != nil {
 		return nil, err
 	}
 	model.AppErrorInit(utils.T)

 	s, err := app.NewServer(
-		app.Config(configDSN, false, nil),
+		app.Config(configDSN, false, readOnlyConfigStore, nil),
 		app.StartSearchEngine,
 	)
 	if err != nil {
--- a/cmd/mattermost/commands/jobserver.go
+++ b/cmd/mattermost/commands/jobserver.go
@@ -34,7 +34,7 @@ func jobserverCmdF(command *cobra.Command, args []string) error {
 	noSchedule, _ := command.Flags().GetBool("noschedule")

 	// Initialize
-	a, err := InitDBCommandContext(getConfigDSN(command, config.GetEnvironment()))
+	a, err := initDBCommandContext(getConfigDSN(command, config.GetEnvironment()), false)
 	if err != nil {
 		return err
 	}
--- a/cmd/mattermost/commands/plugin.go
+++ b/cmd/mattermost/commands/plugin.go
@@ -104,7 +104,7 @@ func init() {
 }

 func pluginAddCmdF(command *cobra.Command, args []string) error {
-	a, err := InitDBCommandContextCobra(command)
+	a, err := InitDBCommandContextCobraReadWrite(command)
 	if err != nil {
 		return err
 	}
@@ -134,7 +134,7 @@ func pluginAddCmdF(command *cobra.Command, args []string) error {
 }

 func pluginDeleteCmdF(command *cobra.Command, args []string) error {
-	a, err := InitDBCommandContextCobra(command)
+	a, err := InitDBCommandContextCobraReadWrite(command)
 	if err != nil {
 		return err
 	}
@@ -158,7 +158,7 @@ func pluginDeleteCmdF(command *cobra.Command, args []string) error {
 }

 func pluginEnableCmdF(command *cobra.Command, args []string) error {
-	a, err := InitDBCommandContextCobra(command)
+	a, err := InitDBCommandContextCobraReadWrite(command)
 	if err != nil {
 		return err
 	}
@@ -182,7 +182,7 @@ func pluginEnableCmdF(command *cobra.Command, args []string) error {
 }

 func pluginDisableCmdF(command *cobra.Command, args []string) error {
-	a, err := InitDBCommandContextCobra(command)
+	a, err := InitDBCommandContextCobraReadWrite(command)
 	if err != nil {
 		return err
 	}
@@ -265,7 +265,7 @@ func pluginPublicKeysCmdF(command *cobra.Command, args []string) error {
 }

 func pluginAddPublicKeyCmdF(command *cobra.Command, args []string) error {
-	a, err := InitDBCommandContextCobra(command)
+	a, err := InitDBCommandContextCobraReadWrite(command)
 	if err != nil {
 		return err
 	}
@@ -296,7 +296,7 @@ func pluginAddPublicKeyCmdF(command *cobra.Command, args []string) error {
 }

 func pluginDeletePublicKeyCmdF(command *cobra.Command, args []string) error {
-	a, err := InitDBCommandContextCobra(command)
+	a, err := InitDBCommandContextCobraReadWrite(command)
 	if err != nil {
 		return err
 	}
--- a/cmd/mattermost/commands/plugin_test.go
+++ b/cmd/mattermost/commands/plugin_test.go
@@ -38,7 +38,7 @@ func TestPlugin(t *testing.T) {

 	fs, err := config.NewFileStore(th.ConfigPath(), false)
 	require.Nil(t, err)
-	cfsStore, err := config.NewStoreFromBacking(fs, nil)
+	cfsStore, err := config.NewStoreFromBacking(fs, nil, false)
 	require.Nil(t, err)
 	require.NotNil(t, cfsStore.Get().PluginSettings.PluginStates["testplugin"])
 	assert.True(t, cfsStore.Get().PluginSettings.PluginStates["testplugin"].Enable)
@@ -48,7 +48,7 @@ func TestPlugin(t *testing.T) {
 	assert.Contains(t, output, "Disabled plugin: testplugin")
 	fs, err = config.NewFileStore(th.ConfigPath(), false)
 	require.Nil(t, err)
-	cfsStore, err = config.NewStoreFromBacking(fs, nil)
+	cfsStore, err = config.NewStoreFromBacking(fs, nil, false)
 	require.Nil(t, err)
 	require.NotNil(t, cfsStore.Get().PluginSettings.PluginStates["testplugin"])
 	assert.False(t, cfsStore.Get().PluginSettings.PluginStates["testplugin"].Enable)
--- a/cmd/mattermost/commands/server.go
+++ b/cmd/mattermost/commands/server.go
@@ -50,7 +50,7 @@ func serverCmdF(command *cobra.Command, args []string) error {
 		mlog.Warn("Error loading custom configuration defaults: " + err.Error())
 	}

-	configStore, err := config.NewStore(getConfigDSN(command, config.GetEnvironment()), !disableConfigWatch, customDefaults)
+	configStore, err := config.NewStore(getConfigDSN(command, config.GetEnvironment()), !disableConfigWatch, false, customDefaults)
 	if err != nil {
 		return errors.Wrap(err, "failed to load configuration")
 	}
--- a/config/common_test.go
+++ b/config/common_test.go
@@ -140,7 +140,7 @@ func TestMergeConfigs(t *testing.T) {
 func TestConfigEnvironmentOverrides(t *testing.T) {
 	memstore, err := config.NewMemoryStore()
 	require.NoError(t, err)
-	base, err := config.NewStoreFromBacking(memstore, nil)
+	base, err := config.NewStoreFromBacking(memstore, nil, false)
 	require.NoError(t, err)
 	originalConfig := &model.Config{}
 	originalConfig.ServiceSettings.SiteURL = newString("http://notoverriden.ca")
@@ -169,7 +169,7 @@ func TestRemoveEnvironmentOverrides(t *testing.T) {

 	memstore, err := config.NewMemoryStore()
 	require.NoError(t, err)
-	base, err := config.NewStoreFromBacking(memstore, nil)
+	base, err := config.NewStoreFromBacking(memstore, nil, false)
 	require.NoError(t, err)
 	oldCfg := base.Get()
 	assert.Equal(t, "http://overridden.ca", *oldCfg.ServiceSettings.SiteURL)
--- a/config/database_test.go
+++ b/config/database_test.go
@@ -120,7 +120,7 @@ func newTestDatabaseStore(t *testing.T, customDefaults *model.Config) (*config.S
 	dss, err := config.NewDatabaseStore(getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource))
 	require.NoError(t, err)

-	cStore, err := config.NewStoreFromBacking(dss, customDefaults)
+	cStore, err := config.NewStoreFromBacking(dss, customDefaults, false)
 	require.NoError(t, err)

 	return cStore, nil
--- a/config/file_test.go
+++ b/config/file_test.go
@@ -91,7 +91,7 @@ func TestFileStoreNew(t *testing.T) {

 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, nil)
+		configStore, err := config.NewStoreFromBacking(fs, nil, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -105,7 +105,7 @@ func TestFileStoreNew(t *testing.T) {

 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, customConfigDefaults)
+		configStore, err := config.NewStoreFromBacking(fs, customConfigDefaults, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -124,7 +124,7 @@ func TestFileStoreNew(t *testing.T) {

 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, nil)
+		configStore, err := config.NewStoreFromBacking(fs, nil, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -138,7 +138,7 @@ func TestFileStoreNew(t *testing.T) {

 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, customConfigDefaults)
+		configStore, err := config.NewStoreFromBacking(fs, customConfigDefaults, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -160,7 +160,7 @@ func TestFileStoreNew(t *testing.T) {
 		path := filepath.Join(tempDir, "does_not_exist")
 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, nil)
+		configStore, err := config.NewStoreFromBacking(fs, nil, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -179,7 +179,7 @@ func TestFileStoreNew(t *testing.T) {
 		path := filepath.Join(tempDir, "does_not_exist")
 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, customConfigDefaults)
+		configStore, err := config.NewStoreFromBacking(fs, customConfigDefaults, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -198,7 +198,7 @@ func TestFileStoreNew(t *testing.T) {
 		path := filepath.Join(tempDir, "does/not/exist")
 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, nil)
+		configStore, err := config.NewStoreFromBacking(fs, nil, false)
 		require.Nil(t, configStore)
 		require.Error(t, err)
 	})
@@ -220,7 +220,7 @@ func TestFileStoreNew(t *testing.T) {

 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, nil)
+		configStore, err := config.NewStoreFromBacking(fs, nil, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -239,7 +239,7 @@ func TestFileStoreNew(t *testing.T) {
 		path := "TestFileStoreNew/a/b/c/config.json"
 		fs, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		configStore, err := config.NewStoreFromBacking(fs, nil)
+		configStore, err := config.NewStoreFromBacking(fs, nil, false)
 		require.NoError(t, err)
 		defer configStore.Close()

@@ -254,7 +254,7 @@ func TestFileStoreGet(t *testing.T) {

 	fs, err := config.NewFileStore(path, false)
 	require.NoError(t, err)
-	configStore, err := config.NewStoreFromBacking(fs, nil)
+	configStore, err := config.NewStoreFromBacking(fs, nil, false)
 	require.NoError(t, err)
 	defer configStore.Close()

@@ -280,7 +280,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -292,7 +292,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, nil)
+		fs, err = config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -306,7 +306,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, customConfigDefaults)
+		fs, err := config.NewStoreFromBacking(fsInner, customConfigDefaults, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -318,7 +318,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, customConfigDefaults)
+		fs, err = config.NewStoreFromBacking(fsInner, customConfigDefaults, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -333,7 +333,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -345,7 +345,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, nil)
+		fs, err = config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -359,7 +359,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -371,7 +371,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, nil)
+		fs, err = config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -385,7 +385,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -397,7 +397,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, nil)
+		fs, err = config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -411,7 +411,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -423,7 +423,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, nil)
+		fs, err = config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -440,7 +440,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -452,7 +452,7 @@ func TestFileStoreGetEnivironmentOverrides(t *testing.T) {

 		fsInner, err = config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err = config.NewStoreFromBacking(fsInner, nil)
+		fs, err = config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -468,7 +468,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -489,7 +489,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -508,7 +508,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -529,7 +529,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -548,7 +548,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -570,7 +570,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -598,7 +598,7 @@ func TestFileStoreSet(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, true)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -630,7 +630,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -647,7 +647,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -671,7 +671,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -696,7 +696,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -721,7 +721,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -746,7 +746,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -771,7 +771,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -798,7 +798,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -820,7 +820,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -841,7 +841,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -860,7 +860,7 @@ func TestFileStoreLoad(t *testing.T) {

 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -887,7 +887,7 @@ func TestFileStoreWatcherEmitter(t *testing.T) {
 		defer tearDown()
 		fsInner, err := config.NewFileStore(path, false)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -913,7 +913,7 @@ func TestFileStoreWatcherEmitter(t *testing.T) {
 		defer tearDown()
 		fsInner, err := config.NewFileStore(path, true)
 		require.NoError(t, err)
-		fs, err := config.NewStoreFromBacking(fsInner, nil)
+		fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 		require.NoError(t, err)
 		defer fs.Close()

@@ -938,7 +938,7 @@ func TestFileStoreSave(t *testing.T) {

 	fsInner, err := config.NewFileStore(path, false)
 	require.NoError(t, err)
-	fs, err := config.NewStoreFromBacking(fsInner, nil)
+	fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 	require.NoError(t, err)
 	defer fs.Close()

@@ -1262,3 +1262,25 @@ func wasCalled(c chan bool, duration time.Duration) bool {
 	}
 	return false
 }
+
+func TestFileStoreReadOnly(t *testing.T) {
+	path, tearDown := setupConfigFile(t, emptyConfig)
+	defer tearDown()
+	fsInner, err := config.NewFileStore(path, true)
+	require.NoError(t, err)
+	fs, err := config.NewStoreFromBacking(fsInner, nil, true)
+	require.NoError(t, err)
+	defer fs.Close()
+
+	called := make(chan bool, 1)
+	callback := func(oldfg, newCfg *model.Config) {
+		called <- true
+	}
+	fs.AddListener(callback)
+
+	cfg, err := fs.Set(minimalConfig)
+	require.Nil(t, cfg)
+	require.Equal(t, config.ErrReadOnlyStore, err)
+
+	require.False(t, wasCalled(called, 1*time.Second), "callback should not have been called since config is read-only")
+}
--- a/config/migrate.go
+++ b/config/migrate.go
@@ -9,13 +9,13 @@ import (

 // Migrate migrates SAML keys, certificates, and other config files from one store to another given their data source names.
 func Migrate(from, to string) error {
-	source, err := NewStore(from, false, nil)
+	source, err := NewStore(from, false, false, nil)
 	if err != nil {
 		return errors.Wrapf(err, "failed to access source config %s", from)
 	}
 	defer source.Close()

-	destination, err := NewStore(to, false, nil)
+	destination, err := NewStore(to, false, false, nil)
 	if err != nil {
 		return errors.Wrapf(err, "failed to access destination config %s", to)
 	}
--- a/config/migrate_test.go
+++ b/config/migrate_test.go
@@ -103,7 +103,7 @@ func TestMigrate(t *testing.T) {

 		sourcedb, err := config.NewDatabaseStore(sourceDSN)
 		require.NoError(t, err)
-		source, err := config.NewStoreFromBacking(sourcedb, nil)
+		source, err := config.NewStoreFromBacking(sourcedb, nil, false)
 		require.NoError(t, err)
 		defer source.Close()

@@ -113,7 +113,7 @@ func TestMigrate(t *testing.T) {

 		destinationfile, err := config.NewFileStore(destinationDSN, false)
 		require.NoError(t, err)
-		destination, err := config.NewStoreFromBacking(destinationfile, nil)
+		destination, err := config.NewStoreFromBacking(destinationfile, nil, false)
 		require.NoError(t, err)
 		defer destination.Close()

@@ -132,7 +132,7 @@ func TestMigrate(t *testing.T) {

 		sourcefile, err := config.NewFileStore(sourceDSN, false)
 		require.NoError(t, err)
-		source, err := config.NewStoreFromBacking(sourcefile, nil)
+		source, err := config.NewStoreFromBacking(sourcefile, nil, false)
 		require.NoError(t, err)
 		defer source.Close()

@@ -142,7 +142,7 @@ func TestMigrate(t *testing.T) {

 		destinationdb, err := config.NewDatabaseStore(destinationDSN)
 		require.NoError(t, err)
-		destination, err := config.NewStoreFromBacking(destinationdb, nil)
+		destination, err := config.NewStoreFromBacking(destinationdb, nil, false)
 		require.NoError(t, err)
 		defer destination.Close()

--- a/config/store.go
+++ b/config/store.go
@@ -14,6 +14,12 @@ import (
 	"github.com/mattermost/mattermost-server/v5/utils/jsonutils"
 )

+var (
+	// ErrReadOnlyStore is returned when an attempt to modify a read-only
+	// configuration store is made.
+	ErrReadOnlyStore = errors.New("configuration store is read-only")
+)
+
 // Listener is a callback function invoked when the configuration changes.
 type Listener func(oldConfig *model.Config, newConfig *model.Config)

@@ -48,13 +54,13 @@ type BackingStore interface {
 }

 // NewStore creates a database or file store given a data source name by which to connect.
-func NewStore(dsn string, watch bool, customDefaults *model.Config) (*Store, error) {
+func NewStore(dsn string, watch, readOnly bool, customDefaults *model.Config) (*Store, error) {
 	backingStore, err := getBackingStore(dsn, watch)
 	if err != nil {
 		return nil, err
 	}

-	store, err := NewStoreFromBacking(backingStore, customDefaults)
+	store, err := NewStoreFromBacking(backingStore, customDefaults, readOnly)
 	if err != nil {
 		backingStore.Close()
 		return nil, errors.Wrap(err, "failed to create store")
@@ -63,10 +69,11 @@ func NewStore(dsn string, watch bool, customDefaults *model.Config) (*Store, err
 	return store, nil
 }

-func NewStoreFromBacking(backingStore BackingStore, customDefaults *model.Config) (*Store, error) {
+func NewStoreFromBacking(backingStore BackingStore, customDefaults *model.Config, readOnly bool) (*Store, error) {
 	store := &Store{
 		backingStore:         backingStore,
 		configCustomDefaults: customDefaults,
+		readOnly:             readOnly,
 	}

 	if err := store.Load(); err != nil {
@@ -96,7 +103,7 @@ func NewTestMemoryStore() *Store {
 		panic("failed to initialize memory store: " + err.Error())
 	}

-	configStore, err := NewStoreFromBacking(memoryStore, nil)
+	configStore, err := NewStoreFromBacking(memoryStore, nil, false)
 	if err != nil {
 		panic("failed to initialize config store: " + err.Error())
 	}
@@ -114,6 +121,7 @@ type Store struct {
 	configCustomDefaults *model.Config

 	persistFeatureFlags bool
+	readOnly            bool
 }

 // Get fetches the current, cached configuration.
@@ -156,6 +164,10 @@ func (s *Store) Set(newCfg *model.Config) (*model.Config, error) {
 	var unlockOnce sync.Once
 	defer unlockOnce.Do(s.configLock.Unlock)

+	if s.readOnly {
+		return nil, ErrReadOnlyStore
+	}
+
 	oldCfg := s.config.Clone()

 	// Really just for some tests we need to set defaults here
@@ -236,7 +248,7 @@ func (s *Store) loadLockedWithOld(oldCfg *model.Config, unlockOnce *sync.Once) e
 	if err != nil {
 		return errors.Wrap(err, "failed to marshal loaded config")
 	}
-	if len(configBytes) == 0 || !bytes.Equal(oldCfgBytes, newCfgBytes) {
+	if !s.readOnly && (len(configBytes) == 0 || !bytes.Equal(oldCfgBytes, newCfgBytes)) {
 		if err := s.backingStore.Set(s.configNoEnv); err != nil {
 			if !errors.Is(err, ErrReadOnlyConfiguration) {
 				return errors.Wrap(err, "failed to persist")
@@ -276,6 +288,9 @@ func (s *Store) GetFile(name string) ([]byte, error) {
 func (s *Store) SetFile(name string, data []byte) error {
 	s.configLock.Lock()
 	defer s.configLock.Unlock()
+	if s.readOnly {
+		return ErrReadOnlyStore
+	}
 	return s.backingStore.SetFile(name, data)
 }

@@ -290,6 +305,9 @@ func (s *Store) HasFile(name string) (bool, error) {
 func (s *Store) RemoveFile(name string) error {
 	s.configLock.Lock()
 	defer s.configLock.Unlock()
+	if s.readOnly {
+		return ErrReadOnlyStore
+	}
 	return s.backingStore.RemoveFile(name)
 }

@@ -304,3 +322,10 @@ func (s *Store) Close() error {
 	defer s.configLock.Unlock()
 	return s.backingStore.Close()
 }
+
+// IsReadOnly returns whether or not the store is read-only.
+func (s *Store) IsReadOnly() bool {
+	s.configLock.RLock()
+	defer s.configLock.RUnlock()
+	return s.readOnly
+}
--- a/config/store_test.go
+++ b/config/store_test.go
@@ -29,26 +29,87 @@ func TestNewStore(t *testing.T) {
 	require.NoError(t, os.Mkdir(filepath.Join(tempDir, "config"), 0700))

 	t.Run("database dsn", func(t *testing.T) {
-		ds, err := config.NewStore(getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource), false, nil)
+		ds, err := config.NewStore(getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource), false, false, nil)
 		require.NoError(t, err)
 		ds.Close()
 	})

 	t.Run("database dsn, watch ignored", func(t *testing.T) {
-		ds, err := config.NewStore(getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource), true, nil)
+		ds, err := config.NewStore(getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource), true, false, nil)
 		require.NoError(t, err)
 		ds.Close()
 	})

 	t.Run("file dsn", func(t *testing.T) {
-		fs, err := config.NewStore("config.json", false, nil)
+		fs, err := config.NewStore("config.json", false, false, nil)
 		require.NoError(t, err)
 		fs.Close()
 	})

 	t.Run("file dsn, watch", func(t *testing.T) {
-		fs, err := config.NewStore("config.json", true, nil)
+		fs, err := config.NewStore("config.json", true, false, nil)
 		require.NoError(t, err)
 		fs.Close()
 	})
 }
+
+func TestNewStoreReadOnly(t *testing.T) {
+	if testing.Short() {
+		t.SkipNow()
+	}
+	sqlSettings := mainHelper.GetSQLSettings()
+
+	tempDir, err := ioutil.TempDir("", "TestNewStore")
+	require.NoError(t, err)
+
+	err = os.Chdir(tempDir)
+	require.NoError(t, err)
+
+	require.NoError(t, os.Mkdir(filepath.Join(tempDir, "config"), 0700))
+
+	t.Run("database dsn", func(t *testing.T) {
+		ds, err := config.NewStore(getDsn(*sqlSettings.DriverName, *sqlSettings.DataSource), false, true, nil)
+		require.NoError(t, err)
+
+		t.Run("Set", func(t *testing.T) {
+			cfg, err := ds.Set(emptyConfig)
+			require.Nil(t, cfg)
+			require.Equal(t, config.ErrReadOnlyStore, err)
+		})
+
+		t.Run("SetFile", func(t *testing.T) {
+			err := ds.SetFile("config.json", []byte{})
+			require.Equal(t, config.ErrReadOnlyStore, err)
+		})
+
+		t.Run("RemoveFile", func(t *testing.T) {
+			err := ds.RemoveFile("config.json")
+			require.Equal(t, config.ErrReadOnlyStore, err)
+		})
+
+		ds.Close()
+	})
+
+	t.Run("file dsn", func(t *testing.T) {
+		fs, err := config.NewStore("config.json", false, true, nil)
+		require.NoError(t, err)
+
+		t.Run("Set", func(t *testing.T) {
+			cfg, err := fs.Set(emptyConfig)
+			require.Nil(t, cfg)
+			require.Equal(t, config.ErrReadOnlyStore, err)
+		})
+
+		t.Run("SetFile", func(t *testing.T) {
+			err := fs.SetFile("config.json", []byte{})
+			require.Equal(t, config.ErrReadOnlyStore, err)
+		})
+
+		t.Run("RemoveFile", func(t *testing.T) {
+			err := fs.RemoveFile("config.json")
+			require.Equal(t, config.ErrReadOnlyStore, err)
+		})
+
+		fs.Close()
+	})
+}
--- a/services/mailservice/mail_test.go
+++ b/services/mailservice/mail_test.go
@@ -129,7 +129,7 @@ func TestSendMailUsingConfig(t *testing.T) {

 	fsInner, err := config.NewFileStore("config.json", false)
 	require.Nil(t, err)
-	fs, err := config.NewStoreFromBacking(fsInner, nil)
+	fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 	require.Nil(t, err)

 	cfg := fs.Get()
@@ -170,7 +170,7 @@ func TestSendMailWithEmbeddedFilesUsingConfig(t *testing.T) {

 	fsInner, err := config.NewFileStore("config.json", false)
 	require.Nil(t, err)
-	fs, err := config.NewStoreFromBacking(fsInner, nil)
+	fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 	require.Nil(t, err)

 	cfg := fs.Get()
@@ -217,7 +217,7 @@ func TestSendMailUsingConfigAdvanced(t *testing.T) {

 	fsInner, err := config.NewFileStore("config.json", false)
 	require.Nil(t, err)
-	fs, err := config.NewStoreFromBacking(fsInner, nil)
+	fs, err := config.NewStoreFromBacking(fsInner, nil, false)
 	require.Nil(t, err)

 	cfg := fs.Get()