Velove Structured Logger

Structured logging & error reporting in GCP for node.js

By default, log messages to stdout (console), but provides an opt-in option to forward logs to Cloud Logging and Error Reporting (GCP)

Severity levels

The different levels are inspired from the Syslog levels

• EMERGENCY: Panic condition: like a system is down
• ALERT: Error requiring immediate attention (potentially corrupted data)
• CRITICAL: Hard issue, system is at risk
• ERROR: program (unexpected) errors to be handled
• WARNING:
• NOTICE: Not errors, but may need some attention
• INFO: Informational messages about the program behavior
• DEBUG: Program debugging informations
• VERBOSE: the highest level, usually for large objects

Usage

Some options can be injected to the exposed "getLogger" function. You can use those to define generic options for your logger, potentially opt-in to GCP Cloud Logging in production for instance.

// logger.ts
import { getLogger as getBaseLogger } from '@velove/structured-logger';

// You can define some flags in env parameters if needed
// And probably define that in a shared file
export const getLogger = (request?: FastifyRequest) =>
  getBaseLogger({
    // default to WARNING
    level: 'WARNING',
    // Default to false, you need to opt-in if you wish to enable Cloud Logging and Error Reporting
    useGoogleCloudAgent: process.env.NODE_ENV === 'production',
    loggerAgentOptions: {
      // Name to identify logs in GCP
      name: 'velove.my-application-name',
      // Can be any string, like a commit hash or something
      version: '1.0.0',
      // Careful with GDPR and other local legislations (default to false)
      logClientIp: false,
      // Those credentials are only needed if you wish to test logging to GCP outside of it (like from your local environment)
      options: {
        projectId: process.env.GCLOUD_PROJECT_ID,
        keyFilename: process.env.GCP_CREDENTIALS_FILE
      }
    },
    request
  });

/** Possible to use directly, but will not be enriched by the HTTP request context */
const requestUnawareLogger = getLogger();

export default requestUnawareLogger;

Within a Fastify server: inject the HTTP request to get an enriched log context

// app.ts
import { getLogger } from 'logger.ts';

app.get('/foo', (request) => {
  const logger = getLogger(request);
  const contextName = 'request.foo'; // up to you

  logger.debug('Hello World', { contextName }); // log with high-level "debug"
  logger.info('My name is Bond. James Bond.', { contextName }); // log with level "info"

  try {
    somethingThatCouldFail();
  } catch (error) {
    logger.error(error, { contextName }); // log an Error object will also forward it to Error Reporting
  }
});

Outside of Fastify, use it straight without the request

import logger from 'logger.ts';

export function myFunction() {
  const logger = logger.warn('"myFunction" is not not 100% reliable yet.', { contextName: 'functions.myFunction' });

  if (Math.random() > 0.9) {
    throw new Error('I did warn you though');
  }
}