title: Handle api calls authentication in scala sangria-graphql
body: <p>I'm developing an api gateway in scala with akka-http and sangria-graphql. The question is how can I ensure that all the api calls are secured?
  more specifically I searched in sangria docs and came out to add some sort of middleware that handles this operation (in my case I should use OAuth2 and Google APIs).
  But, since I'm not so experienced with this stack, I founded hard to retrieve some documentation or projects to study from.</p>
  <p>Thanks in advance for the answers.</p>