Ngx Runtime Initializer

NgxRuntimeInitializer is an Angular utility for loading runtime configuration from JSON, managing global app settings, and optionally injecting services with post-initialization callbacks. Perfect for SSR, feature toggles, and dynamic environment configuration.

Features

• Load runtime configuration (config.json or custom URL) at app initialization.
• Validate essential properties (apiURL, debug, requestTimeout).
• Inject services into post-initialization logic.
• Support fallback configuration on failure.
• Provides Angular signals for reactive configuration.
• Built-in guards for maintenance mode or app status handling.

Installation

Install via npm:

npm install ngx-runtime-initializer

Usage

1. Define your runtime config JSON

// config.json
{
  "coreConfig": {
    "apiURL": "https://api.example.com",
    "debug": true,
    "requestTimeout": 30000
  },
  "status": true
}

2. Provide the runtime initializer in standalone bootstrap

import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app/app.component';
import { provideRuntimeInitializer } from 'ngx-runtime-initializer';

bootstrapApplication(AppComponent, {
  providers: [provideRuntimeInitializer()],
});

✅ Loads config.json with default behavior.

3. Custom initialization

import { RuntimeInitializerOptions, provideRuntimeInitializer } from 'ngx-runtime-initializer';
import { MyService1, MyService2 } from './services';

bootstrapApplication(AppComponent, {
  providers: [
    provideRuntimeInitializer(
      new RuntimeInitializerOptions(
        '/assets/runtime-config.json',
        [MyService1, MyService2],
        async (config, services) => {
          console.log('Config loaded:', config);
          services.MyService1?.initialize();
        },
        (error, services) => {
          console.warn('Failed to initialize runtime config:', error);
        }
      )
    ),
  ],
});

4. Accessing configuration

import { inject } from '@angular/core';
import { AppConfigService } from 'ngx-runtime-initializer';

const appConfigService = inject(AppConfigService);

// Full config
const config = appConfigService.getConfig();

// Specific property
const apiURL = appConfigService.getConfigProperty<string>('coreConfig')?.apiURL;

// Reactive signal
const configSignal = appConfigService.getConfigSignal();

5. Guards for maintenance and status

import { InMaintenanceGuard, MaintenanceGuard, createStatusGuard } from 'ngx-runtime-initializer';

{
  path: 'maintenance',
  canActivate: [InMaintenanceGuard]
}

{
  path: '',
  canActivate: [MaintenanceGuard]
}

// Or create a custom guard
{
  path: 'custom',
  canActivate: [createStatusGuard(true, '/maintenance')]
}

API

RuntimeInitializerOptions

Class to configure the runtime initializer.

Constructor

new RuntimeInitializerOptions(
  configUrl?: string,
  servicesToInject?: Type<any>[],
  postInit?: (config: AppConfig, services: Record<string, any>) => Promise<void>,
  handleInitializationFailure?: (error: any, services: Record<string, any>) => void
)

Defaults:

• configUrl = 'config.json'
• servicesToInject = []
• postInit = async () => {}
• handleInitializationFailure = () => {}

provideRuntimeInitializer(options?: RuntimeInitializerOptions)

Provides an Angular provideAppInitializer — equivalent to APP_INITIALIZER in pre-standalone Angular versions — to load runtime configuration.

AppConfigService

• getConfig(): AppConfig — Returns full config.
• getConfigProperty<T>(key: keyof AppConfig): T | undefined — Returns a specific property.
• getConfigSignal(): WritableSignal<AppConfig> — Reactive configuration.
• getStatus(): boolean — Returns app status.

AppConfig

Default configuration class:

coreConfig = { apiURL: '__BACKEND__', debug: false, requestTimeout: 30000 };
status = false;

License

This project is licensed under the MIT License - see the LICENSE file for details.