API Design with Node.js V4

Let's create a new file src/config/index.ts. Then, for every environment, we'll create a file. Those enviroments are local, staging, and production.

So create, src/config/local.ts, src/config/staging.ts, src/config/prod.ts. Each of one these files will be used to configure variables for their matching environment.

Next, we'll merge the configs together, giving us our final config that we can use anywhere.
In `src/config/index.ts`

import merge from "lodash.merge";

// make sure NODE_ENV is set
process.env.NODE_ENV = process.env.NODE_ENV || "development";

const stage = process.env.STAGE || "local";
let envConfig;

// dynamically require each config depending on the stage we're in
if (stage === "production") {
  envConfig = require("./prod").default;
} else if (stage === "staging") {
  envConfig = require("./staging").default;
} else {
  envConfig = require("./local").default;
}

const defaultConfig = {
  stage,
  dbUrl: process.env.DATABASE_URL,
  jwtSecret: process.env.JWT_SECRET,
  port: process.env.PORT,
  logging: false,
};

export default merge(defaultConfig, envConfig);