autotel/dist/logger.d.cts

Write Once, Observe Anywhere

export { Logger as PinoLogger } from 'pino';

/**
 * Zero-dependency structured logger for autotel
 *
 * This logger provides:
 * - Structured JSON logging (production) or pretty print (development)
 * - Auto trace context injection (traceId, spanId, correlationId)
 * - Dynamic log level control (per-request via OTel context)
 * - Level support (debug, info, warn, error, none)
 * - Zero additional dependencies (uses @opentelemetry/api, already a dep)
 *
 * Uses Pino-compatible signature supporting both patterns:
 * - `log.info('simple message')` - string-only
 * - `log.info({ userId: '123' }, 'message')` - object first with optional message
 *
 * Used as the default fallback when users don't provide Pino/Bunyan.
 * Can also be used directly: import { createBuiltinLogger } from 'autotel/logger'
 *
 * @example
 * ```typescript
 * import { createBuiltinLogger, runWithLogLevel } from 'autotel/logger';
 *
 * const log = createBuiltinLogger('my-service');
 *
 * // Simple message (no metadata)
 * log.info('Server started');
 *
 * // With metadata (Pino-style: object first, message second)
 * log.info({ userId: '123' }, 'User created');
 * // Output: {"level":"info","service":"my-service","msg":"User created","userId":"123","traceId":"..."}
 *
 * // Dynamic log level per-request
 * runWithLogLevel('debug', () => {
 *   log.debug('This will log even if default level is "info"');
 * });
 * ```
 */

type BuiltinLogLevel = 'debug' | 'info' | 'warn' | 'error' | 'none';
/**
 * Get the active log level from context (if set)
 * Falls back to undefined if no log level is set in context
 */
declare function getActiveLogLevel(): BuiltinLogLevel | undefined;
/**
 * Run a function with a specific log level
 * The log level is stored in OpenTelemetry context and applies to all logger calls within the callback
 *
 * @example
 * ```typescript
 * // Enable debug logging for a specific request
 * runWithLogLevel('debug', () => {
 *   log.debug('This will be logged');
 *   processRequest();
 * });
 *
 * // Disable logging temporarily
 * runWithLogLevel('none', () => {
 *   log.info('This will NOT be logged');
 * });
 * ```
 */
declare function runWithLogLevel<T>(level: BuiltinLogLevel, callback: () => T): T;
/**
 * Helper to get trace context (useful for BYOL - Bring Your Own Logger)
 *
 * @example
 * ```typescript
 * import bunyan from 'bunyan';
 * import { getTraceContext } from 'autotel/logger';
 *
 * const bunyanLogger = bunyan.createLogger({ name: 'myapp' });
 * const ctx = getTraceContext();
 * bunyanLogger.info({ ...ctx, email: 'test@example.com' }, 'Creating user');
 * ```
 */
declare function getTraceContext(): {
    traceId: string;
    spanId: string;
    correlationId: string;
} | null;
interface BuiltinLoggerOptions {
    /** Minimum log level. Default: 'info' */
    level?: BuiltinLogLevel;
    /** Pretty print for development. Default: false (JSON output) */
    pretty?: boolean;
}
/**
 * Create a lightweight structured logger
 *
 * @param service - Service name for logging
 * @param options - Optional configuration
 *
 * @example
 * ```typescript
 * const log = createBuiltinLogger('user-service');
 *
 * log.info('Creating user', { email: 'test@example.com' });
 * // Output: {"level":"info","service":"user-service","msg":"Creating user",
 * //          "email":"test@example.com","traceId":"...","spanId":"..."}
 *
 * // Dynamic log level control per-request
 * runWithLogLevel('debug', () => {
 *   log.debug('This will be logged even if logger was created with level: "info"');
 * });
 * ```
 */
declare function createBuiltinLogger(service: string, options?: BuiltinLoggerOptions): Logger;
/**
 * Pino-like factory function for creating an autotel logger
 *
 * @example
 * ```typescript
 * import { autotelLogger } from 'autotel/logger';
 *
 * const log = autotelLogger();
 *
 * // Simple message
 * log.info('Server started');
 *
 * // With metadata (Pino-style: object first, message second)
 * log.info({ userId: '123' }, 'User created');
 *
 * // With options
 * const devLog = autotelLogger({ service: 'my-app', level: 'debug', pretty: true });
 * ```
 */
declare function autotelLogger(options?: {
    service?: string;
    level?: BuiltinLogLevel;
    pretty?: boolean;
}): Logger;

/**
 * Logger types and utilities for autotel
 *
 * **Zero-Config Option:** Don't provide a logger to `init()` and autotel uses
 * a built-in structured JSON logger with automatic trace context injection.
 *
 * **BYOL (Bring Your Own Logger):** Pass Pino or Bunyan to `init()` for
 * automatic instrumentation with trace context and OTLP log export.
 *
 * ## Logger Signature
 *
 * Autotel v2.10+ uses **Pino's signature**: `logger.info({ metadata }, 'message')`.
 *
 * ### Backward Compatibility
 *
 * The built-in logger auto-detects legacy Winston-style calls and swaps arguments:
 * ```typescript
 * // Legacy (auto-detected and handled)
 * logger.info('User created', { userId: '123' });
 * // → Internally treated as: logger.info({ userId: '123' }, 'User created')
 * // → Logs warning in development, works silently in production
 * ```
 *
 * ### Recommended Usage
 *
 * ```typescript
 * // ✅ Pino-style (preferred)
 * logger.info({ userId: '123' }, 'User created');
 *
 * // ✅ Simple message (no metadata)
 * logger.info('Server started');
 * ```
 *
 * **Note:** If you BYOL (bring your own logger), it must use Pino signature.
 * Winston and other `(message, meta)` loggers are NOT compatible.
 * For Winston, use `@opentelemetry/instrumentation-winston` instead.
 *
 * @example Zero-config (uses built-in logger)
 * ```typescript
 * import { init } from 'autotel';
 *
 * init({ service: 'my-app' });
 * // Internal logs: {"level":"info","service":"my-app","msg":"...","traceId":"..."}
 * ```
 *
 * @example Using built-in logger directly
 * ```typescript
 * import { createBuiltinLogger, runWithLogLevel } from 'autotel/logger';
 *
 * const log = createBuiltinLogger('my-service');
 *
 * // Simple message (no metadata)
 * log.info('Server started');
 *
 * // With metadata (Pino-style: object first, message second)
 * log.info({ userId: '123' }, 'User created');
 * // Output: {"level":"info","service":"my-service","msg":"User created","userId":"123","traceId":"..."}
 *
 * // Dynamic log level per-request
 * runWithLogLevel('debug', () => {
 *   log.debug('Debug info for this request only');
 * });
 * ```
 *
 * @example Using Pino (recommended for production, auto-instrumented)
 * ```typescript
 * import pino from 'pino';  // npm install pino
 * import { init } from 'autotel';
 *
 * const logger = pino({ level: 'info' });
 * init({ service: 'my-app', logger });
 *
 * // Logs automatically include traceId/spanId and export via OTLP!
 * logger.info({ userId: '123' }, 'User created');
 * ```
 *
 * @example Using Bunyan (auto-instrumented, same signature as Pino)
 * ```typescript
 * import bunyan from 'bunyan';  // npm install bunyan @opentelemetry/instrumentation-bunyan
 * import { init } from 'autotel';
 * import { BunyanInstrumentation } from '@opentelemetry/instrumentation-bunyan';
 *
 * const logger = bunyan.createLogger({ name: 'my-app' });
 * init({
 *   service: 'my-app',
 *   logger,
 *   instrumentations: [new BunyanInstrumentation()]
 * });
 * ```
 *
 * @example Custom logger (MUST use Pino-compatible signature)
 * ```typescript
 * // ⚠️ Your custom logger MUST accept (object, message?) signature
 * const logger = {
 *   info: (extra, msg) => console.log(msg || '', extra),
 *   warn: (extra, msg) => console.warn(msg || '', extra),
 *   error: (extra, msg) => console.error(msg || '', extra),
 *   debug: (extra, msg) => console.debug(msg || '', extra),
 * };
 * init({ service: 'my-app', logger });
 * ```
 *
 * @example BYOL helper: inject trace context into any logger
 * ```typescript
 * import bunyan from 'bunyan';
 * import { getTraceContext } from 'autotel/logger';
 *
 * const bunyanLogger = bunyan.createLogger({ name: 'myapp' });
 * const ctx = getTraceContext();
 * bunyanLogger.info({ ...ctx, userId: '123' }, 'Creating user');
 * ```
 */
/**
 * Log level constants
 */
declare const LOG_LEVEL: {
    readonly DEBUG: "debug";
    readonly INFO: "info";
    readonly WARN: "warn";
    readonly ERROR: "error";
};
type LogLevel = (typeof LOG_LEVEL)[keyof typeof LOG_LEVEL];
/**
 * Logger configuration (for reference - not needed with BYOL approach)
 */
interface LoggerConfig {
    service: string;
    level?: LogLevel;
    pretty?: boolean;
    redact?: string[] | false;
}
/**
 * Pino-compatible log function signature
 *
 * Matches Pino's actual LogFn type which supports:
 * - `(msg: string)` - simple string message
 * - `(obj: object, msg?: string)` - object first with optional message
 *
 * @example
 * ```typescript
 * logger.info('User logged in');
 * logger.info({ userId: '123' }, 'User created');
 * logger.error({ err: error }, 'Operation failed');
 * ```
 */
interface LogFn {
    (msg: string): void;
    (obj: Record<string, unknown>, msg?: string): void;
}
/**
 * Simple logger interface - Pino/Bunyan-compatible
 *
 * Uses Pino's LogFn signature which supports both:
 * - `logger.info('message')` - simple string message
 * - `logger.info({ extra }, 'message')` - object first with optional message
 *
 * This is compatible with Pino, Bunyan, and any logger following this pattern.
 *
 * @example Using Pino (just works!)
 * ```typescript
 * import pino from 'pino';
 * const logger = pino({ level: 'info' });
 * init({ service: 'my-app', logger });
 * ```
 *
 * @example Direct usage
 * ```typescript
 * logger.info('Simple message');
 * logger.info({ userId: '123' }, 'User created');
 * logger.error({ err: error }, 'Operation failed');
 * ```
 */
interface Logger {
    info: LogFn;
    warn: LogFn;
    error: LogFn;
    debug: LogFn;
}
/**
 * Alias for Logger interface (backwards compatibility)
 * @deprecated Use Logger instead
 */
type ILogger = Logger;

interface LoggedOperationOptions {
    /** Operation name for tracing (e.g., 'user.createUser') */
    operationName: string;
}
/**
 * TS5+ Standard Decorator for logging and tracing operations
 * Uses TC39 Stage 3 decorator syntax
 *
 * This is the traditional per-method decorator approach.
 * For zero-boilerplate solution, see @Instrumented class decorator.
 *
 * @example
 * // Simple usage (Pino-style: object first, message second)
 * class OrderService {
 *   constructor(private readonly deps: { log: Logger }) {}
 *
 *   @LoggedOperation('order.create')
 *   async createOrder(data: CreateOrderData) {
 *     // ✅ Correct Pino-style logging
 *     this.deps.log.info({ orderId: data.id }, 'Creating order');
 *   }
 * }
 *
 * // Advanced usage (future-proof for options)
 * @LoggedOperation({ operationName: 'order.create' })
 * async createOrder(data: CreateOrderData) { }
 */
declare function LoggedOperation(operationNameOrOptions: string | LoggedOperationOptions): <This, Args extends unknown[], Return>(originalMethod: (this: This, ...args: Args) => Promise<Return>, context: ClassMethodDecoratorContext<This, (this: This, ...args: Args) => Promise<Return>>) => (this: This, ...args: Args) => Promise<Return>;

export { type BuiltinLogLevel, type BuiltinLoggerOptions, type ILogger, LOG_LEVEL, type LogFn, type LogLevel, LoggedOperation, type LoggedOperationOptions, type Logger, type LoggerConfig, autotelLogger, createBuiltinLogger, getActiveLogLevel, getTraceContext, runWithLogLevel };