Environment Configuration

The logger auto-configures based on your environment.

Auto-Detection

The logger reads NODE_ENV (and Vite's MODE/PROD/DEV) and applies these defaults:

Setting	Development	Test	Production	Undetected
minLevel	trace	trace	info	trace
pretty	✅	✅	❌ (JSON)	✅
colors	✅	✅	❌	✅
redact	❌	❌	✅	✅

Undetected means no NODE_ENV, no Vite signal, and no explicit env option — this can happen on some edge/serverless runtimes. Redaction defaults on in that case: a logger must never silently leak secrets just because a platform doesn't expose NODE_ENV. Set env: 'development' explicitly (or redact: false) if you genuinely want unredacted output on such a platform, e.g. for local development against an edge runtime emulator.

Development Mode

When NODE_ENV !== 'production' (and explicitly resolved, not merely undetected):

• All logs visible — trace through fatal
• Pretty output — human-readable, colorful
• No redaction — see full data for debugging

10:30:00 DEBUG [App] User login { password: 'secret123' }

Production Mode

When NODE_ENV === 'production':

• Info and above — trace/debug filtered out
• JSON output — for log aggregators (Datadog, Splunk, etc.)
• Redaction enabled — sensitive data protected

{"timestamp":"...","level":"info","message":"User login","data":{"password":"[REDACTED]"}}

Override Environment

Force Environment Mode

// Force production mode (even in development)
const log = createLogger('App', { env: 'production' });

// Force development mode (even in production, or on an undetected runtime)
const log = createLogger('App', { env: 'development' });

Override Individual Settings

// Production JSON + debug logs
const log = createLogger('App', {
  env: 'production',
  minLevel: 'debug',
});

// Development pretty + redaction enabled
const log = createLogger('App', {
  env: 'development',
  redact: true,
});

Conditional Configuration

const isProd = process.env.NODE_ENV === 'production';

const log = createLogger('App', {
  minLevel: isProd ? 'info' : 'trace',
  redact: isProd,
  pretty: !isProd,
});

Using env Option

const log = createLogger('App', {
  env: process.env.NODE_ENV as 'development' | 'test' | 'production',
});

Environment Variables

Variable	Description
NODE_ENV	'production' enables JSON output and redaction; unset/undetected also enables redaction (fail-safe)
DEBUG	'true' enables debug level in production
ENABLE_DEBUG_LOGS	Alternative to DEBUG
NO_COLOR	Disable colored output
FORCE_COLOR	Force colored output

These are read automatically by createLogger() — there is no separate step to wire them up. If you want to read your own LOG_LEVEL/LOG_ENABLED/LOG_NAMESPACES variables and apply them globally at startup, do that explicitly with configure() — see Global Configuration.

Example .env Files

# .env.development
NODE_ENV=development

# .env.production
NODE_ENV=production

# .env.test
NODE_ENV=test

Common Configurations

API Server (Production)

const log = createLogger('API', {
  env: 'production',
  minLevel: 'info',
  metadata: {
    service: 'user-api',
    version: process.env.npm_package_version,
  },
});

Debug Mode in Production

const log = createLogger('App', {
  env: 'production',
  minLevel: process.env.DEBUG === 'true' ? 'debug' : 'info',
});

CI/Test Environment

const log = createLogger('Test', {
  env: 'test',
  silent: process.env.CI === 'true', // Silent in CI
});