gc-json-logger

Async Context Structured Logger for GCP projects

Allows printing logs to stdout, stderr for further action in Google Cloud platform. Given that log agent ingests logs from stdout streams when running in GKE.

Precaution

A logger makes use of async_hooks module which is currently experimental. However, the use of async_hooks mechanism was at basic.

Installation

npm install --save gc-json-logger

yarn add gc-json-logger

View in Google Cloud Logging

Integration

const { Logger } = require('gc-json-logger');
const { createServer } = require('http');

let job = 0;

function scheduleJob() {
  /**
   * 4) Retrieving a context logger
   */
  const logger = Logger.getLogger();

  /**
   * 5) Logs with job id from the parent
   */
  logger.info('scheduling job');

  setTimeout(() => {
    /**
     * 6) Logs with job id from the parent
     */
    logger.info('job done');
  }, 3000);
}

const server = createServer((_, res) => {
  job++;

  /**
   * 1) Setting a context logger using job id
   */
  const logger = new Logger(job);
  Logger.setLogger(logger);

  /**
   * 2) Logs with with job id
   */
  logger.info('creating a new job');

  /**
   * 3) Calls another function that uses the context
   */
  scheduleJob();

  res.setHeader('content-type', 'application/json');
  res.end(JSON.stringify({ id: job, status: 'scheduled' }));
});

server.listen(8080);

{
  "severity": "INFO",
  "time": "2022-12-03T10:00:00.000Z",
  "message": "creating a new job",
  "logging.googleapis.com/operation": { "id": 1 } // <- always includes context id
}

{
  "severity": "INFO",
  "time": "2022-12-03T10:00:00.398Z",
  "message": "scheduling job",
  "logging.googleapis.com/operation": { "id": 1 } // <- always includes context id
}

{
  "severity": "INFO",
  "time": "2022-12-03T10:00:01.000Z",
  "message": "job done",
  "logging.googleapis.com/operation": { "id": 1 } // <- always includes context id
}