Angular 2 and Team City Production/Environment Variables

Question

We have a new Angular app that is building AOT to a folder. Everything is working fine, but we are trying to configure it to a five-step build process using TeamCity/Octopus

Answer 1

I would build on the config.js idea you have. The config should be loaded as part of the application startup, not part of the build. You need to make a service that loads the config.js on startup of your application, use the APP_INITIALIZER provider and pass it the factory that creates the service. Here is an example:

app.module.ts

import { NgModule, APP_INITIALIZER } from '@angular/core';

@NgModule({
    imports: [
        ....
    ],
    declarations: [
        ....
    ],
    providers: [
        {
            provide: APP_INITIALIZER,
            useFactory: configServiceFactory,
            deps: [ConfigService, Http, AppConfig],
            multi: true
        },
        AppConfig,
        ConfigService
    ],
    bootstrap: [AppComponent]
})
export class AppModule {
}

Config Service:

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';

import { AppConfig } from '../../app.config';

@Injectable()
export class ConfigService {
    private _config: AppConfig;

    constructor(private http: Http, private config: AppConfig) {
    }

    public Load(): Promise<AppConfig> {
        return new Promise((resolve) => {
            this.http.get('./config.json').map(res => res.json())
            .subscribe((config: AppConfig) => {
                this.copyConfiguration(config, new AppConfig()).then((data: AppConfig) => {
                    this._config = data;
                    resolve(this._config);
                });
            }, (error: any) => {
                this._config = new AppConfig();
                resolve(this._config);
            });
        });
    }

    public GetApiUrl(endPoint: any): string {
        return `${this._config.ApiUrls.BaseUrl}/${this._config.ApiUrls[ endPoint ]}`;
    }

    public GetApiEndPoint(endPoint: any): string {
        return this._config.ApiUrls[ endPoint ];
    }

    public Get(key: any): any {
        return this._config[ key ];
    }

    private copyConfiguration(source: Object, destination: Object): any {
        return new Promise(function(resolve) {
            Object.keys(source).forEach(function(key) {
                destination[ key ] = source[ key ];
                resolve(destination);
            });
        });
    }
}

export function configServiceFactory(config: ConfigService) {
    return () => config.Load();
}