upd(internal):

- don't provide fault db connection setting
- prefix is optional, check if we have it

internal/config/database.go

@@ -30,11 +30,14 @@ func (*Database) Init(prefix ...string) *Database {
 	}
 
 	p := func(s string) string {
-		return prefix[0] + "-" + s
+		if len(prefix) > 0 {
+			return prefix[0] + "-" + s
+		}
+		return s
 	}
 
 	db = new(Database)
-	flag.StringVar(&db.DSN, p("db-dsn"), "crust:crust@tcp(db1:3306)/crust?collation=utf8mb4_general_ci", "DSN for database connection")
+	flag.StringVar(&db.DSN, p("db-dsn"), "", "DSN for database connection (e.g. user:pass@tcp(db1:3306)/dbname?collation=utf8mb4_general_ci)")
 	flag.StringVar(&db.Profiler, p("db-profiler"), "", "Profiler for DB queries (none, stdout)")
 	return db
 }

internal/config/http.go

@@ -38,7 +38,10 @@ func (*HTTP) Init(prefix ...string) *HTTP {
 	}
 
 	p := func(s string) string {
-		return prefix[0] + "-" + s
+		if len(prefix) > 0 {
+			return prefix[0] + "-" + s
+		}
+		return s
 	}
 
 	http = new(HTTP)