workspace-ionic-app/src/app/app.module.ts

import { HttpClientModule } from '@angular/common/http';
import { APP_INITIALIZER, NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouteReuseStrategy } from '@angular/router';
import { KeycloakAngularModule, KeycloakService } from 'keycloak-angular';
import { IonicModule, IonicRouteStrategy } from '@ionic/angular';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import {initializeKeycloak} from './_helper/keycloak-init.factory'
import { D4sAuthService } from './d4sauth.service';

@NgModule({
  declarations: [AppComponent],
  imports: [BrowserModule, IonicModule.forRoot(), AppRoutingModule, HttpClientModule, HttpClientModule, KeycloakAngularModule],
  
  providers: [
    D4sAuthService,
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy },
    {
        provide: APP_INITIALIZER,
        useFactory: initializeKeycloak,
        multi: true,
        deps: [KeycloakService]
    },
    
    ],
  bootstrap: [AppComponent]
})
export class AppModule {
  
  constructor() { 
	}
  
}