├── application // Interface layer and Application Services in hexagonal architecture
│   ├── cmd // command line interface
│   ├── controller // http controller
│   ├── middleware // http middleware, it can wrap errors or set request uuid or jwt authorization
│   └── routes // http router
├── domain // domain layer
│   ├── entity
│   ├── repository // same as Port in hexagonal architecture
│   ├── service // domain service layer
│   └── vo // value object
├── go.mod
├── infrastructure // infrastructure layer in hexagonal
│   ├── clients // external APIs (E.g. google client, firebase client ..)
│   ├── configs // configuration of fiber app 
│   ├── logger
│   └── persistence // Impl of /domain/repository interface, database persistence layer(E.g. mysql, postgreSQL, mongo, redis ..)
└── pre-commit.example // go fmt before commit