An opinionated Google Cloud structured logger

google-cloud-structured-logger.ts

/**
 * Google's logging enums:
 * DEFAULT 	(0) The log entry has no assigned severity level.
 * DEBUG 	(100) Debug or trace information.
 * INFO 	(200) Routine information, such as ongoing status or performance.
 * NOTICE 	(300) Normal but significant events, such as start up, shut down, or a configuration change.
 * WARNING 	(400) Warning events might cause problems.
 * ERROR 	(500) Error events are likely to cause problems.
 * CRITICAL 	(600) Critical events cause more severe problems or outages.
 * ALERT 	(700) A person must take an action immediately.
 * EMERGENCY 	(800) One or more systems are unusable.
 */
export enum GoogleLogSeverity {
  DEFAULT = 'DEFAULT',
  DEBUG = 'DEBUG',
  INFO = 'INFO',
  NOTICE = 'NOTICE',
  WARNING = 'WARNING',
  ERROR = 'ERROR',
  CRITICAL = 'CRITICAL',
  ALERT = 'ALERT',
  EMERGENCY = 'EMERGENCY'
}

/**
 * A simple (opinionated) logger that can be used in a cloud function.
 *
 * If you're using it in an app, consider Pino logger.
 */
export class GcLogger {
  default(message: string, context: any): void {
    this.log(GoogleLogSeverity.DEFAULT, message, context);
  }

  debug(message: string, context: any): void {
    this.log(GoogleLogSeverity.DEBUG, message, context);
  }

  info(message: string, context: any): void {
    this.log(GoogleLogSeverity.INFO, message, context);
  }

  notice(message: string, context: any): void {
    this.log(GoogleLogSeverity.NOTICE, message, context);
  }

  warning(message: string, context: any): void {
    this.log(GoogleLogSeverity.WARNING, message, context);
  }

  error(message: string, context: any): void {
    this.log(GoogleLogSeverity.ERROR, message, context);
  }

  critical(message: string, context: any): void {
    this.log(GoogleLogSeverity.CRITICAL, message, context);
  }

  alert(message: string, context: any): void {
    this.log(GoogleLogSeverity.ALERT, message, context);
  }

  emergency(message: string, context: any): void {
    this.log(GoogleLogSeverity.EMERGENCY, message, context);
  }

  log(level: GoogleLogSeverity, message: string, context: any): void {
    // Note: you could use process.stdout.write instead of console.log. The point here is just to get the log printed
    // as a JSON object and Google will take care of the rest.
    console.log(
      JSON.stringify({
        severity: level,
        message: message,
        context: context
      })
    );
  }
}