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Logger

The Logger interface provides structured logging across all Pikku services and functions. Every singleton service set includes a logger, and it's available in all function contexts via services.logger.

Interface​

The Logger interface is minimal by design — it matches the common subset of popular logging libraries:

logger.ts
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Each method accepts either a string message or a structured object:

logger.info('User signed in')
logger.info({ userId: 'user-123', action: 'sign-in' })
logger.error(new Error('Connection failed'))

Implementations​

ConsoleLogger (built-in)​

The default logger that wraps console.*. No additional packages required:

logger-console.ts
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import { ConsoleLogger } from '@pikku/core/services'

const logger = new ConsoleLogger()

PinoLogger​

For production use with structured JSON output, use the Pino wrapper from @pikku/pino:

npm install @pikku/pino pino
import { PinoLogger } from '@pikku/pino'

const logger = new PinoLogger()
logger.setLevel('info') // Uses LogLevel enum mapping

The PinoLogger exposes the underlying pino.Logger instance via logger.pino for advanced configuration.

Custom Logger​

Any object that implements the Logger interface works. If your logging library already has info, warn, error, and debug methods, you can cast it directly:

import winston from 'winston'

const logger = winston.createLogger({
  transports: [new winston.transports.Console()],
}) as unknown as Logger

Log Levels​

Use setLevel() to control verbosity:

import { LogLevel } from '@pikku/core/services'

logger.setLevel(LogLevel.debug) // Show all logs
logger.setLevel(LogLevel.warn)  // Only warnings and errors

Registration​

Pass the logger when creating singleton services:

const singletonServices = await createSingletonServices(config, {
  logger: new PinoLogger(),
})