Hands-On Microservices with Kubernetes

Employing interfaces and contracts

Interfaces are one of the best tools a software engineer can use. Once you expose something as an interface, you can freely change the implementation behind it. Interfaces are a construct that's being used within a single process. They are extremely useful for testing interactions with other components, which are plentiful in microservice-based systems. Here is one of the interfaces of our sample application:

type UserManager interface {   Register(user User) error   Login(username string, authToken string) (session string, err error)   Logout(username string, session string) error}

The UserManager interface defines a few methods, their inputs, and outputs. However, it doesn't specify the semantics. For example, ...