Bootstrapping a default Firebase app

firebase-app.provider.ts

import { OpaqueToken, Provider, provide } from '@angular/core';
import * as firebase from 'firebase';

export const FIREBASE_APP = new OpaqueToken('FIREBASE_APP');
export const firebaseAppProvider = (config: Object): Provider => {
  return provide(FIREBASE_APP, {useFactory: () => {
      return firebase.initializeApp(config);
  }});
};

main.ts

import { bootstrap } from '@angular/platform-browser-dynamic';
import { provide } from '@angular/core';

import { firebaseAppProvider } from './firebase/firebase-app.provider';
import { AppComponent } from './app/app.component';

bootstrap(AppComponent, [
    firebaseAppProvider({
        apiKey: "<APIKEY>",
        authDomain: "<DOMAIN>.firebaseapp.com",
        databaseURL: "https://<DOMAIN>.firebaseio.com",
        storageBucket: "<DOMAIN>.appspot.com"
    })

]);

some-data.service.ts

import { Injectable, Inject } from '@angular/core';
import { FIREBASE_APP } from '../../firebase/firebase-app.provider';
import * as firebase from 'firebase';

@Injectable()
export class SomeDataService {
    // consume from the default app...
    constructor(@Inject(FIREBASE_APP) public app: firebase.app.App) {}
    
}