feat(instrumentation): work on settings model for internal metrics publishing, #4696

pkg/setting/setting.go

@@ -37,9 +37,10 @@ const (
 
 var (
 	// App settings.
-	Env       string = DEV
-	AppUrl    string
-	AppSubUrl string
+	Env          string = DEV
+	AppUrl       string
+	AppSubUrl    string
+	InstanceName string
 
 	// build
 	BuildVersion string
@@ -259,6 +260,12 @@ func evalEnvVarExpression(value string) string {
 		envVar = strings.TrimPrefix(envVar, "${")
 		envVar = strings.TrimSuffix(envVar, "}")
 		envValue := os.Getenv(envVar)
+
+		// if env variable is hostname and it is emtpy use os.Hostname as default
+		if envVar == "HOSTNAME" && envValue == "" {
+			envValue, _ = os.Hostname()
+		}
+
 		return envValue
 	})
 }
@@ -395,11 +402,28 @@ func validateStaticRootPath() error {
 	return fmt.Errorf("Failed to detect generated css or javascript files in static root (%s), have you executed default grunt task?", StaticRootPath)
 }
 
+// func readInstanceName() string {
+// 	hostname, _ := os.Hostname()
+// 	if hostname == "" {
+// 		hostname = "hostname_unknown"
+// 	}
+//
+// 	instanceName := Cfg.Section("").Key("instance_name").MustString("")
+// 	if instanceName = "" {
+// 		// set value as it might be used in other places
+// 		Cfg.Section("").Key("instance_name").SetValue(hostname)
+// 		instanceName = hostname
+// 	}
+//
+// 	return
+// }
+
 func NewConfigContext(args *CommandLineArgs) error {
 	setHomePath(args)
 	loadConfiguration(args)
 
 	Env = Cfg.Section("").Key("app_mode").MustString("development")
+	InstanceName = Cfg.Section("").Key("instance_name").MustString("unknown_instance_name")
 	PluginsPath = Cfg.Section("paths").Key("plugins").String()
 
 	server := Cfg.Section("server")