Weenie Service Manager

This package is meant to be used with Weenie. However, if you are not using Weenie but are interested in this functionality, there's nothing wrong with using it directly.

Functionality

The main export of this library is the serviceManager function, which returns a svc dependency with three properties: whenReady: Promise<void>, declareReady: () => void and onShutdown: (task: () => Promise<void>) => void. See src/serviceManager.ts for more detailed documentation.

• Startup monitoring - Sets a timeout (configurable with config.svc.initializationTimeoutMs) that kills the process if the svc.declareReady() function is not called within the configured time. When svc.declareReady() is called, the svc.whenReady promise is resolved, allowing dependents to activate functionality when all dependencies are known to be ready.
• Shutdown management - If configured to do so (with config.svc.handleShutdown), registers event listeners on SIGINT and SIGTERM signals and runs any shutdown tasks prior to exiting the process. Shutdown tasks may be registered by passing a function returning a promise to the svc.onShutdown() function. For example, you may want to close your database cleanly on shutdown, so you might pass svc.onShutdown(() => db.close()). (Note: this shutdown functionality is also accessible to the running application via the svc.shutdown() function.)

Config

See src/serviceManager.ts for config options. (If you use a modern editor like vscode, the documentation should pop up on mouse-over.)

Example

import { Weenie, logger, serviceManager } from '@wymp/weenie-framework';

const config = {
  logger: {
    logLevel: 'notice',
  },
  svc: {
    initializationTimeoutMs: 10_000,
    handleShutdown: true,
  },
}

const deps = Weenie({ config })
  .and(logger)
  .and(serviceManager)
  .done((d) => d);

// Do other setup ....
deps.svc.whenReady.then(() => deps.log.notice(`Service started!`));
deps.svc.onShutdown(async () => { deps.log.notice(`Service shutting down`) });

// Now let everything know the service is ready to start
deps.svc.declareReady();