Environment

A Reactive Environment Management for JS Applications.

About The Project

This library provides an environment properties store that is populated by asyncronous sources and exposes a query to get the values, as well a service to modify them at runtime.

The common way to manage the application properties in JavaScript frameworks is to define environment values in a constant or env file and load them at build stage. This strategy is not suitable for developments where, for example, the final build is deployed in a repositoy manager such as Nexus or Artifactory and reused in diferent environments, or in a microservices architecture where the properties are loaded from a config manager service. This library addresses this and other gaps by allowing, among others, the following behaviors:

• Get properties from constants
• Get properties from local sources, such as files
• Get properties from remote HTTP sources, such as a REST API
• Get properties from remote streaming sources, such as a WebSocket server
• Get properties from sources with interdependencies
• Get properties from multiple sources in order, unordered or by mixing strategies
• Stop source or application loading after a trigger
• Wait until required sources or properties are setted to load the application
• Define if the properties from a source should overwrite the existing ones or to merge with them
• Manage the loading lifecycle with hooks
• Implement a middleware to intercept the added properties

Getting Started

Installation

npm install --save @kuoki/environment

Usage

The steps to generate an environment manager are described below. Each of the steps is described in depth, with examples and common hacks, in the documentation of each module.

1. Implement and instantiate an EnvironmentStore gateway object so that the library uses the same state manager as the rest of the application.
2. Create an instance of EnvironmentService to handle the modification of environment properties.
3. Create an instance of EnvironmentQuery to get environment properties.
4. Implement and instantiate as many EnvironmentSource gateway objects as needed to get the environment properties.
5. Create an instance of EnvironmentLoader to get the properties from the sources.

import { createEnvironmentLoader, createEnvironmentQuery, createEnvironmentService } from '@kuoki/environment';
import { BehaviorSubject } from 'rxjs';

const initialState = {};
const state = new BehaviorSubject(initialState);
const store = {
  getAll$: () => state.asObservable(),
  getAll: () => state.getValue(),
  update: (environment) => state.next(environment),
  reset: () => state.next(initialState)
};

// env.json = { userName: 'JohnDoe01' }
const fileSource = {
  isRequired: true,
  load: async () => fetch('env.json')
};
const constSource = {
  isRequired: true,
  load: () => [{ name: 'John Doe' }]
};

const service = createEnvironmentService(store);
const query = createEnvironmentQuery(store);
const loader = createEnvironmentLoader(service, [fileSource, constSource]);

loader.load().then(() => {
  console.log(query.getAll()); // LOG {name:'John Doe',userName:'JohnDoe01'}
});