/**
 * Logger that does nothing.
 * @hidden
 */
export declare class NullLogger implements Logger {
    static instance: Logger;
    child(options: LoggerOptions): Logger;
    trace(...args: any[]): void;
    debug(...args: any[]): void;
    info(...args: any[]): void;
    warn(...args: any[]): void;
    error(...args: any[]): void;
    fatal(...args: any[]): void;
}
/**
 * A logger that conforms for the [bunyan](https://www.npmjs.com/package/bunyan) logger interface.
 */
export interface Logger {
    /**
     * Creates a child logger with the given options.
     * @param options Logger options.
     */
    child(options: LoggerOptions): Logger;
    /**
     * Creates a log record with the TRACE log level.
     * @param error The error to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    trace(error: Error, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the TRACE log level.
     * @param fields Set of additional fields to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    trace(fields: Object, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the TRACE log level.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    trace(msg: string, ...params: any[]): void;
    /**
     * Creates a log record with the DEBUG log level.
     * @param error The error to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    debug(error: Error, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the DEBUG log level.
     * @param fields Set of additional fields to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    debug(fields: Object, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the DEBUG log level.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    debug(msg: string, ...args: any[]): void;
    /**
     * Creates a log record with the INFO log level.
     * @param error The error to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    info(error: Error, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the INFO log level.
     * @param fields Set of additional fields to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    info(fields: Object, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the INFO log level.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    info(msg: string, ...args: any[]): void;
    /**
     * Creates a log record with the WARN log level.
     * @param error The error to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    warn(error: Error, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the WARN log level.
     * @param fields Set of additional fields to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    warn(fields: Object, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the WARN log level.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    warn(msg: string, ...args: any[]): void;
    /**
     * Creates a log record with the ERROR log level.
     * @param error The error to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    error(error: Error, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the ERROR log level.
     * @param fields Set of additional fields to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    error(fields: Object, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the ERROR log level.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    error(msg: string, ...args: any[]): void;
    /**
     * Creates a log record with the FATAL log level.
     * @param error The error to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    fatal(error: Error, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the FATAL log level.
     * @param fields Set of additional fields to log.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    fatal(fields: Object, msg?: string, ...args: any[]): void;
    /**
     * Creates a log record with the FATAL log level.
     * @param msg Log message. This can be followed by additional arguments for printf-like formatting.
     */
    fatal(msg: string, ...args: any[]): void;
}
/**
 * Logger options.
 */
export interface LoggerOptions {
    /**
     * Dictionary of custom serializers. The key is the name of the property that is serialized and the the value
     * is a function that takes an object and returns a JSON serializable value.
     */
    serializers?: {
        [key: string]: (input: any) => any;
    };
}