APP_CONFIG

1. in module provider

{ provide: APP_CONFIG, useValue: AppConfig }

2. app.config.ts

import { InjectionToken } from "@angular/core";
import { IAuthConfig } from "../service/Authentication/auth.config";
import { environment } from 'src/environments/environment';

export let APP_CONFIG = new InjectionToken("app.config");

export interface IAppConfig {
    dateFormat: string;
    dateFormatMomentJs: string;
    environment: string;
    apiEndpoint: string;
    appAgencyWebUrl: string;
    appFinanceWebUrl: string;
    appCssFullUrl: string;
    appFeedbackMailTo: string;
    authConfig: IAuthConfig;
    applicationVersionInfo: any;
    userInfo: any;
    validatorMetaData: any;
    uiSettings: any;   
}

export let AppConfig: IAppConfig = {
    dateFormat: "dd MMM yyyy",
    dateFormatMomentJs: "DD MMM YYYY",
    environment: "",
    apiEndpoint: environment.apiEndpoint,
    appAgencyWebUrl: "",
    appFinanceWebUrl: '',
    appCssFullUrl: "",
    appFeedbackMailTo: "",
    authConfig: { applicationName: null, authEndpoint: null, contactAdmin: null, staffPortal: null, storedTokenName: 'admissionsToken' },
    validatorMetaData: {
    },
    applicationVersionInfo: {},
    userInfo: {},
    uiSettings: {
    }
};

3. use in component

in constructor

@Inject(APP_CONFIG) private config: IAppConfig

I can use value in config

APP_INITIALIZER

1. in module provider

{ provide: APP_INITIALIZER, useFactory: (config: ServerConfigInitializer) => () => config.load(), deps: [ServerConfigInitializer], multi: true },

2. server.config.initializer.ts

import { Inject, Injectable } from '@angular/core';
import { Observable, throwError } from 'rxjs';
import { catchError } from 'rxjs/operators';
import { TokenService } from '../service/Authentication/token.service';
import { ConfigurationDataService } from '../service/configuration.data.service';
import { APP_CONFIG, IAppConfig } from '../config/app.config';

@Injectable()
export class ServerConfigInitializer {

    private result: Object = null;

    constructor( @Inject(APP_CONFIG) private config: IAppConfig,
        private configurationDataService: ConfigurationDataService,
        private tokenService: TokenService) {
    }

    public getResult() {
        return this.result;
    }

    public load() {
        return new Promise((resolve, reject) => {
            this.configurationDataService.getConfigurationSettings()
                .pipe(catchError((error: any): any => {
                    reject(false);
                    return throwError(error.json().error || 'Server error');
                })).subscribe((data: any) => {
                    this.config.validatorMetaData = data.validatorMetaData;
                    this.config.environment = data.environment;
                    this.config.apiEndpoint = data.appApiUrl;
                    this.config.appAgencyWebUrl = data.appAgencyWebUrl;
                    this.config.appFinanceWebUrl = data.appFinanceWebUrl;
                    this.config.appCssFullUrl = data.appCssFullUrl;
                    this.config.appFeedbackMailTo = data.appFeedbackMailTo;
                    this.config.authConfig = data.authServiceConfig;
                    this.config.applicationVersionInfo = data.applicationVersionInfo;
                    resolve(true);
                });

        });
    }
}

this provider will be execute when application is initializing, can set value to APP_CONFIG to share among the project