Setting Up Cloud Logging for Node.js

For Node.js applications, plugins are maintained for the popular Winston and Bunyan logging libraries. Winston is a general-purpose library, implementing a variety of log formatters and transports. Bunyan, which is specialized for structured JSON logs, supports log formatting by piping to the Bunyan command line.

You can also use the Logging client library for Node.js directly, or create your own integrations with your preferred logging library. For example, you can use the Pino log framework example.

The Logging agent doesn't have to be installed to use the Winston or Bunyan on a Compute Engine virtual machine (VM) instance.

Before you begin

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

Enable the Cloud Logging API.

Enable the API

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

Enable the Cloud Logging API.

Enable the API

Prepare your environment for Node.js development.
Go to the Node.js setup guide

Configure logging

This section describes how to install and configure the plugins for the Winston and Bunyan logging libraries. For Bunyan, information is provided about how to use Bunyan with a Node.js Express application.

You can use other libraries or frameworks. For example, you can use the Pino log framework. For sample code that uses OpenTelemetry to collect metrics and trace data, and the Pino log framework to collect log data, see Generate traces and metrics with Node.js. If you use Pino, then you must implement a mapping between the Pino severity levels and those used by Cloud Logging. For example code, see Mapping Pino Log Levels.

Install and configure the Winston plugin

Cloud Logging provides a plugin for the Winston Node.js Logging library. The Logging plugin for Winston provides a simpler, higher-level layer for working with Logging.

To install and configure the Winston plugin, do the following:

To install the Logging Winston plugin, use npm:

npm install --save @google-cloud/logging-winston winston

Import the plugin and add it to your Winston configuration:

const winston = require('winston');

// Imports the Google Cloud client library for Winston
const {LoggingWinston} = require('@google-cloud/logging-winston');

const loggingWinston = new LoggingWinston();

// Create a Winston logger that streams to Cloud Logging
// Logs will be written to: "projects/YOUR_PROJECT_ID/logs/winston_log"
const logger = winston.createLogger({
  level: 'info',
  transports: [
    new winston.transports.Console(),
    // Add Cloud Logging
    loggingWinston,
  ],
});

// Writes some log entries
logger.error('warp nacelles offline');
logger.info('shields at 99%');

Configure your plugin.

You can customize the behavior of the Winston plugin using the same configuration options supported by the Cloud Logging API Cloud client library for Node.js. These options can be passed in the options object passed to the plugin's constructor.

Install and configure the Bunyan plugin

Cloud Logging provides a plugin for the Bunyan Node.js Logging library. The Logging plugin for Bunyan provides a simpler, higher-level layer for working with Logging.

To install and configure the Bunyan plugin, do the following:

To install the Logging Bunyan plugin, use npm:

npm install --save bunyan @google-cloud/logging-bunyan

Import the plugin and add it to your Bunyan configuration:

const bunyan = require('bunyan');

// Imports the Google Cloud client library for Bunyan
const {LoggingBunyan} = require('@google-cloud/logging-bunyan');

// Creates a Bunyan Cloud Logging client
const loggingBunyan = new LoggingBunyan();

// Create a Bunyan logger that streams to Cloud Logging
// Logs will be written to: "projects/YOUR_PROJECT_ID/logs/bunyan_log"
const logger = bunyan.createLogger({
  // The JSON payload of the log as it appears in Cloud Logging
  // will contain "name": "my-service"
  name: 'my-service',
  streams: [
    // Log to the console at 'info' and above
    {stream: process.stdout, level: 'info'},
    // And log to Cloud Logging, logging at 'info' and above
    loggingBunyan.stream('info'),
  ],
});

// Writes some log entries
logger.error('warp nacelles offline');
logger.info('shields at 99%');

Configure your plugin.

You can customize the behavior of the Bunyan plugin using the same configuration options supported by the Cloud Logging API Cloud client library for Node.js. These options can be passed in the options object passed to the plugin's constructor.

Use Bunyan and Express

You can set up and use Bunyan with Logging in a Node.js Express application.

// Imports the Google Cloud client library for Bunyan.
const lb = require('@google-cloud/logging-bunyan');

// Import express module and create an http server.
const express = require('express');

async function startServer() {
  const {logger, mw} = await lb.express.middleware({
    logName: 'samples_express',
  });
  const app = express();

  // Install the logging middleware. This ensures that a Bunyan-style `log`
  // function is available on the `request` object. This should be the very
  // first middleware you attach to your app.
  app.use(mw);

  // Setup an http route and a route handler.
  app.get('/', (req, res) => {
    // `req.log` can be used as a bunyan style log method. All logs generated
    // using `req.log` use the current request context. That is, all logs
    // corresponding to a specific request will be bundled in the Stackdriver
    // UI.
    req.log.info('this is an info log message');
    res.send('hello world');
  });

  const port = process.env.PORT || 8080;

  // `logger` can be used as a global logger, one not correlated to any specific
  // request.
  logger.info({port}, 'bonjour');

  // Start listening on the http server.
  const server = app.listen(port, () => {
    console.log(`http server listening on port ${port}`);
  });

  app.get('/shutdown', (req, res) => {
    res.sendStatus(200);
    server.close();
  });
}

startServer();

For more information on installation, see the documentation for the Cloud Logging libraries for Node.js. You can also report issues using the issue tracker.

Write logs with the Cloud Logging client library

For information on using the Cloud Logging client library for Node.js directly, see Cloud Logging Client Libraries.

Run on Google Cloud

For an application to write logs by using the Cloud Logging libraries for Node.js, the service account for the underlying resource must have the Logs Writer (roles/logging.logWriter) IAM role. Most Google Cloud environments automatically configure the default service account to have this role.

App Engine

Cloud Logging is automatically enabled for App Engine, and your app's default service account has the IAM permissions by default to write log entries.

To write log entries from your app, we recommend that you use Bunyan or Winston as described on this page.

For more information, see Writing and viewing logs.

Google Kubernetes Engine (GKE)

GKE automatically grants the default service account the Logs Writer (roles/logging.logWriter) IAM role. If you use Workload Identity Federation for GKE with this default service account to let workloads access specific Google Cloud APIs, then no additional configuration is required. However, if you use Workload Identity Federation for GKE with a custom IAM service account, then ensure that the custom service account has the role of Logs Writer (roles/logging.logWriter).

If needed, you can also use the following command to add the logging.write access scope when creating the cluster:

gcloud container clusters create example-cluster-name \
    --scopes https://www.googleapis.com/auth/logging.write

Compute Engine

When using Compute Engine VM instances, add the cloud-platform access scope to each instance. When creating a new instance through the Google Cloud console, you can do this in the Identity and API access section of the Create Instance panel. Use the Compute Engine default service account or another service account of your choice, and select Allow full access to all Cloud APIs in the Identity and API access section. Whichever service account you select, ensure that it has been granted the Logs Writer role in the IAM & Admin section of the Google Cloud console.

Cloud Run functions

Cloud Run functions grants the Logs Writer role by default.

The Cloud Logging libraries for Node.js can be used without needing to explicitly provide credentials.

Cloud Run functions is configured to use Cloud Logging automatically.

Run locally and elsewhere

To use the Cloud Logging libraries for Node.js outside of Google Cloud, including running the library on your own workstation, on your data center's computers, or on the VM instances of another cloud provider, you must supply your Google Cloud project ID and appropriate service account credentials directly to the Cloud Logging libraries for Node.js.

For existing service accounts, do the following:

Grant the service account the IAM the Logs Writer (roles/logging.logWriter) IAM role. For more information on IAM roles, see Access control.
Set up Application Default Credentials.

If you don't have a service account, then create one. For information about this process, see Create service accounts.

For general information about the methods that you can use to authenticate, see Terminology: service accounts.

Use Winston:

// Imports the Google Cloud client library for Winston
const {LoggingWinston} = require('@google-cloud/logging-winston');

// Creates a client
const loggingWinston = new LoggingWinston({
  projectId: 'your-project-id',
  keyFilename: '/path/to/key.json',
});

Use Bunyan:

// Imports the Google Cloud client library for Bunyan
const {LoggingBunyan} = require('@google-cloud/logging-bunyan');

// Creates a client
const loggingBunyan = new LoggingBunyan({
  projectId: 'your-project-id',
  keyFilename: '/path/to/key.json',
});

View the logs

In the Google Cloud console, go to the Logs Explorer page:

Go to Logs Explorer

If you use the search bar to find this page, then select the result whose subheading is Logging.

In the Logs Explorer, you must specify one or more resources, but the resource selection might not be obvious. Here are some tips to help you get started:

If you are deploying your application to App Engine or using the App Engine-specific libraries, set your resource to GAE Application.
If you are deploying your application on Compute Engine, set the resource to GCE VM Instance.
If you are deploying your application on Google Kubernetes Engine, your cluster's logging configuration determines the resource type of the log entries. For a detailed discussion on the Legacy Google Cloud Observability and the Google Cloud Observability Kubernetes Monitoring solutions, and how those options affect the resource type, see Migrating to Google Cloud Observability Kubernetes Monitoring.
If your application is using the Cloud Logging API directly, the resource is dependent on the API and your configuration. For example, in your application, you can specify a resource or use a default resource.
If you don't see any logs in the Logs Explorer, to see all log entries, switch to the advanced query mode and use an empty query.
1. To switch to the advanced query mode, click menu (▾) at the top of the Logs Explorer and then select Convert to advanced filter.
2. Clear the content that appears in the filter box.
3. Click Submit Filter.
You can examine the individual entries to identify your resources.

For additional information, see Using the Logs Explorer.