Secrets Handling

Overview

Never hardcode secrets. Never commit secrets. Never log secrets.

Secrets in code end up in version control, logs, error messages, and eventually in attackers' hands.

When to Use

• Working with API keys, tokens, passwords
• Configuring database connections
• Setting up third-party service credentials
• Asked to "just hardcode it for now"

The Iron Rule

NEVER put secrets in source code.

No exceptions:

• Not for "just for testing"
• Not for "it's a private repo"
• Not for "I'll remove it later"
• Not for "it's not a real secret"

Detection: Hardcoded Secret Smell

If you see literal credentials, STOP:

// ❌ VIOLATION: Hardcoded secrets
const stripe = new Stripe('sk_live_abc123xyz');

const db = mysql.connect({
  password: 'super_secret_password'
});

const API_KEY = 'AIzaSyD-xxxxxxxxxxxxx';

Problems:

• Secrets in git history forever
• Visible in code reviews
• Exposed in error stack traces
• Shared with anyone who has repo access

The Correct Pattern: Environment Variables

// ✅ CORRECT: Environment variables
import { z } from 'zod';

// Validate env vars at startup
const envSchema = z.object({
  STRIPE_SECRET_KEY: z.string().startsWith('sk_'),
  DATABASE_URL: z.string().url(),
  API_KEY: z.string().min(1),
});

const env = envSchema.parse(process.env);

// Use validated env vars
const stripe = new Stripe(env.STRIPE_SECRET_KEY);

# .env (NEVER commit this file)
STRIPE_SECRET_KEY=sk_live_abc123xyz
DATABASE_URL=postgres://user:pass@host:5432/db
API_KEY=your-api-key

# .gitignore (ALWAYS include)
.env
.env.*
!.env.example

# .env.example (commit this - no real values)
STRIPE_SECRET_KEY=sk_test_xxx
DATABASE_URL=postgres://localhost:5432/myapp
API_KEY=your-api-key-here

Secrets Hygiene Rules

1. Environment Variables

const secret = process.env.SECRET_KEY;

2. Validate at Startup

if (!process.env.API_KEY) {
  throw new Error('API_KEY environment variable is required');
}

3. Never Log Secrets

// ❌ BAD
console.log('Connecting with:', connectionString);

// ✅ GOOD
console.log('Connecting to database...');

4. Mask in Error Messages

// ❌ BAD
throw new Error(`Auth failed for key: ${apiKey}`);

// ✅ GOOD
throw new Error('Authentication failed');

5. Use Secret Managers in Production

// AWS Secrets Manager, HashiCorp Vault, etc.
const secret = await secretsManager.getSecret('my-api-key');

Pressure Resistance Protocol

1. "Just for Testing"

Pressure: "Hardcode it for now, we'll fix it later"

Response: "Later" never comes. Secrets in history stay forever.

Action: Use env vars from the start. It takes 30 seconds.

2. "It's a Private Repo"

Pressure: "Only the team has access"

Response: Teams change. Repos get cloned. Access expands.

Action: Never commit secrets regardless of repo visibility.

3. "I'll Remove It Later"

Pressure: "Just for this one commit"

Response: Git history is permanent. The secret is already leaked.

Action: If you committed a secret, rotate it immediately.

4. "It's Not a Real Secret"

Pressure: "This is just a test key"

Response: Test keys become production keys. Treat all secrets equally.

Action: Use env vars for all credentials.

Red Flags - STOP and Reconsider

• Literal strings that look like keys/tokens
• password:, secret:, key: in source
• .env file not in .gitignore
• Secrets in error messages or logs
• Credentials in config files that get committed

All of these mean: Move to environment variables immediately.

If You Accidentally Committed a Secret

1. Rotate the secret immediately - consider it compromised
2. Remove from code and commit
3. Consider git history rewriting (but assume it's leaked)
4. Check for unauthorized usage

Quick Reference

Do	Don't
Environment variables	Hardcoded strings
.env in .gitignore	Commit .env files
.env.example with placeholders	Real values in examples
Validate env at startup	Fail silently on missing
Secret managers in prod	Env vars in containers

Common Rationalizations (All Invalid)

Excuse	Reality
"Just for testing"	Testing secrets become production secrets.
"Private repo"	Private today, leaked tomorrow.
"I'll remove it"	Git history is forever.
"Not a real secret"	All credentials deserve protection.
"It's encrypted"	Keys to decrypt are also secrets.
"Only local use"	Local files get committed.

The Bottom Line

Secrets live in environment, never in code.

Use environment variables. Validate at startup. Never log credentials. Never commit .env files. If you leak a secret, rotate it immediately.