Authorization bearer token Angular 5

I suggest to use HttpInterceptor for setting default HTTP headers on outgoing requests rather than adding an additional HTTP header to each call.

HTTP Client – Setting default headers @ angular.io

In your example you can do the following:

import { Http, Headers, Response } from '@angular/http';

getLoggedInUser(auth_token): Observable<any> {
  const headers = new Headers({
    'Content-Type': 'application/json',
    'Authorization': `Bearer ${auth_token}`
  })
  return this.http.get(apiUrl, { headers: headers })
}