AuthService - Async HTTP Interceptors with Angular 4

auth.service.ts

import { Injectable } from '@angular/core';
import { UserManager, User } from 'oidc-client';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/fromPromise';

@Injectable()
export class AuthService {

    private userManager: UserManager;

    constructor () {
        this.userManager = new UserManager({
            // options
        });
    }

    getUser (): Promise<User> {
        return Observable.fromPromise(this.userManager.getUser());
    }
    
    // new
    login () {
        // redirect user to login page
        this.userManager.signinRedirect();
    }
                                                  
}

Updated gist for ng 6.x and rxjs 6.x