MM-21285: Remove environment overrides before config broadcast (#13527)

While sending the config broadcast message across a cluster, we would
include the environment overrides in the config.

We fix this by exposing a config config store method to remove the overrides,
and then calling that before saving the config across the cluster.

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

app/config.go

@@ -395,6 +395,7 @@ func (a *App) SaveConfig(newCfg *model.Config, sendConfigChangeClusterMessage bo
 	}
 
 	if a.Cluster != nil {
+		newCfg = a.Srv.configStore.RemoveEnvironmentOverrides(newCfg)
 		err := a.Cluster.ConfigChanged(oldCfg, newCfg, sendConfigChangeClusterMessage)
 		if err != nil {
 			return err

config/common.go

@@ -77,7 +77,7 @@ func (cs *commonStore) set(newCfg *model.Config, allowEnvironmentOverrides bool,
 		}
 	}
 
-	if err := persist(cs.removeEnvOverrides(newCfg)); err != nil {
+	if err := persist(cs.RemoveEnvironmentOverrides(newCfg)); err != nil {
 		return nil, errors.Wrap(err, "failed to persist")
 	}
 
@@ -164,7 +164,7 @@ func (cs *commonStore) validate(cfg *model.Config) error {
 	return nil
 }
 
-// removeEnvOverrides returns a new config without the given environment overrides.
-func (cs *commonStore) removeEnvOverrides(cfg *model.Config) *model.Config {
+// RemoveEnvironmentOverrides returns a new config without the given environment overrides.
+func (cs *commonStore) RemoveEnvironmentOverrides(cfg *model.Config) *model.Config {
 	return removeEnvOverrides(cfg, cs.configWithoutOverrides, cs.environmentOverrides)
 }

config/common_test.go

@@ -162,5 +162,17 @@ func TestConfigEnvironmentOverrides(t *testing.T) {
 	})
 }
 
+func TestRemoveEnvironmentOverrides(t *testing.T) {
+	os.Setenv("MM_SERVICESETTINGS_SITEURL", "http://overridden.ca")
+	defer os.Unsetenv("MM_SERVICESETTINGS_SITEURL")
+
+	base, err := config.NewMemoryStore()
+	require.NoError(t, err)
+	oldCfg := base.Get()
+	assert.Equal(t, "http://overridden.ca", *oldCfg.ServiceSettings.SiteURL)
+	newCfg := base.RemoveEnvironmentOverrides(oldCfg)
+	assert.Equal(t, "", *newCfg.ServiceSettings.SiteURL)
+}
+
 func newBool(b bool) *bool       { return &b }
 func newString(s string) *string { return &s }

config/store.go

@@ -20,6 +20,10 @@ type Store interface {
 	// GetEnvironmentOverrides fetches the configuration fields overridden by environment variables.
 	GetEnvironmentOverrides() map[string]interface{}
 
+	// RemoveEnvironmentOverrides returns a new config without the environment
+	// overrides
+	RemoveEnvironmentOverrides(cfg *model.Config) *model.Config
+
 	// Set replaces the current configuration in its entirety and updates the backing store.
 	Set(*model.Config) (*model.Config, error)