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How do you manage configuration in a Node.js application for different environments?

Q: How do you manage configuration in a Node.js application for different environments?

**TL;DR.** Keep configuration **in the environment**, not in code, and **layer** it: sensible defaults → per-environment overrides → environment variables/secrets (highest precedence). Validate the merged config **once at startup** into a typed object, so dev/staging/prod differ only by their env, not their build. defaults (lowest) per-env file staging/prod <path class='d-edge-accent' d='M304 74 H342' marker-e

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Layered, validated config module

import { z } from 'zod';

const defaults = { logLevel: 'info', cacheTtl: 60 };
const Schema = z.object({
  logLevel: z.string(),
  cacheTtl: z.coerce.number(),
  databaseUrl: z.string().url(),
});

export const config = Object.freeze(Schema.parse({
  ...defaults,
  logLevel: process.env.LOG_LEVEL ?? defaults.logLevel,  // env wins
  databaseUrl: process.env.DATABASE_URL,
}));

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