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Express Example

This example shows how to use dotenv-gad in an Express application to validate environment variables and fail fast if required configuration is missing.

Schema (env.schema.ts):

import { defineSchema } from 'dotenv-gad';

export default defineSchema({
  PORT: { type: 'number', default: 3000, docs: 'Port to run the server on' },
  DATABASE_URL: { type: 'string', required: true, sensitive: true },
});

Server (server.ts):

import express from 'express';
import schema from './env.schema';
import { loadEnv } from 'dotenv-gad';

const env = loadEnv(schema); // throws on validation errors

const app = express();
app.get('/', (req, res) => res.send('Hello'));

app.listen(env.PORT, () => console.log(`Server running on ${env.PORT}`));

Notes

  • loadEnv reads from both process.env and your .env file. On platforms like Vercel, Railway, or Docker where env vars are injected directly, it just works — no .env file needed.
  • Use includeRaw during local debugging if you want raw values to appear in errors: loadEnv(schema, { includeRaw: true }).
  • For production, keep includeRaw disabled to avoid leaking values in logs.

Try it online

cd examples/express
npm ci
npm start