title: How to secure communication in a server-server app?
body: <p>I have a microservices based web app. Microservices communicate with each other via a REST API exposed. I want an easy, yet secure solution to secure communication between my microservices. I've already used JWT protocol to secure my user-services communication but I can't figure out the best way to secure server-server communication.</p>
  
  <p>Update:
  I want an easy way to authenticate APIs. Is is a good way to hardcode key and secret or put them in configurations files and then use them to authenticate to an other end point?
  I've heard about OAuth2 protocol but I'm afraid it's an overkill for my need.So What can be the easy and secure way to authenticate APIs?</p>