@idoconfig/base v1.3.4

Configuration

tl;dr Provide app configuration as key-value pairs from different providers. Inspired by ASP.net Core IConfiguration

Motivation

Providing app configuration in Node projects seems surprisingly hard. There are a million ways to choose from citation needed. Environment variables, JSON files... Well, that's two. But even with environment variables there are at least two different approaches. The real env vars (available via process.env.ENV_VAR_NAME) and the .env file. When using the .env file you'll most likely use the dotenv package.

This package was inspired by the ASP.net (Core) IConfiguration approach. A single class instance that you can pass around via DI (or any other way) and query for values.

Example

const providers = [
    new EnvVarConfigurationProvider();
    new JsonConfigurationProvider();
];
const config = new Configuration(providers);

const value  = config.getValue("ENV_VAR"); // Returns a single value, eg. "my-value"
const section = config.getSection("foo"); // Returns an object, eg. { "key-a": "value-a", "key-b": "value-b", ... }

Note: In your application you'll probably setup the providers via dependency injection.

Dependency injection

In your inversify.config.ts file do this:

import Container from "inversify";
import { Configuration, ExampleConfigProvider, IConfiguration, IConfigurationValueProvider } from "idoconfig";

const di = new Container({ defaultScope: "Singleton" });

decorate(injectable(), Configuration);
decorate(injectable(), ExampleConfigProvider);

di.bind<IConfigurationValueProvider>("ConfigProvider").to(ExampleConfigProvider);
di.bind<IConfiguration>("Configuration").to(Configuration);

Please note: ExampleConfigProvider does exist in this repository. Nor elsewhere.

Tests

Written in TypeScript, done with Mocha & Chai. Here's a working VS Code launch configuration:

{
    "type": "node",
    "request": "launch",
    "name": "Tests",
    "program": "${workspaceRoot}/node_modules/mocha/bin/_mocha",
    "cwd": "${workspaceRoot}",
    "args": [
        "-u", "tdd",
        "--no-timeouts",
        "-r", "ts-node/register",
        "--colors",
        "${workspaceRoot}/test/**/*test.ts"
    ],
    "protocol": "inspector",
    "sourceMaps": true,
    "internalConsoleOptions": "openOnSessionStart"
}

Provider Options

You can pass provider-specific options to provider class instances. The only (optional) default member is the name property. You may implement other behaviour as you see fit (e.g. key/value formatters).

interface IConfigurationValueProviderOptions {
    name?: string;
}