RBAC: Feature to override default assignments (#66561)

* RBAC: Feature to override default assignments

Co-authored-by: Kalle Persson <kalle.persson@grafana.com>

* Add test and trim spaces

* Pass linting

* Apply the rbac overrides to fixed_authentication.config_writer

* Removing from the default ini file for now

* Add grants overrides section to cfg

* slimmer handleGrantOverrides function

---------

Co-authored-by: Kalle Persson <kalle.persson@grafana.com>

pkg/setting/setting.go

@@ -505,6 +505,9 @@ type Cfg struct {
 	RBACPermissionValidationEnabled bool
 	// Reset basic roles permissions on start-up
 	RBACResetBasicRoles bool
+	// Override default fixed role assignments
+	RBACGrantOverrides map[string][]string
+
 	// GRPC Server.
 	GRPCServerNetwork   string
 	GRPCServerAddress   string
@@ -1559,6 +1562,17 @@ func readAccessControlSettings(iniFile *ini.File, cfg *Cfg) {
 	cfg.RBACPermissionCache = rbac.Key("permission_cache").MustBool(true)
 	cfg.RBACPermissionValidationEnabled = rbac.Key("permission_validation_enabled").MustBool(false)
 	cfg.RBACResetBasicRoles = rbac.Key("reset_basic_roles").MustBool(false)
+
+	rbacOverrides := iniFile.Section("rbac.overrides")
+	cfg.RBACGrantOverrides = map[string][]string{}
+	for _, key := range rbacOverrides.Keys() {
+		value := key.MustString("")
+		grants := strings.Split(value, ",")
+		for i, grant := range grants {
+			grants[i] = strings.TrimSpace(grant)
+		}
+		cfg.RBACGrantOverrides[key.Name()] = grants
+	}
 }
 
 func readUserSettings(iniFile *ini.File, cfg *Cfg) error {