Cloud Logging: Node.js Client

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Google Cloud Logging allows you to store, search, analyze, monitor, and alert on log data and events from Google Cloud Platform and Amazon Web Services.

If you require lightweight dependencies, an experimental, minified version of this library is available at @google-cloud/logging-min. Note: logging-min is experimental, and its feature surface is subject to change.

A comprehensive list of changes in each version may be found in the CHANGELOG.

Read more about the client libraries for Cloud APIs, including the older Google APIs Client Libraries, in Client Libraries Explained.

Table of contents:

Quickstart

Before you begin

  1. Select or create a Cloud Platform project.
  2. Enable the Cloud Logging API.
  3. Set up authentication with a service account so you can access the API from your local workstation.

Installing the client library

npm install @google-cloud/logging

Using the client library

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

async function quickstart(
  projectId = 'YOUR_PROJECT_ID', // Your Google Cloud Platform project ID
  logName = 'my-log' // The name of the log to write to
) {
  // Creates a client
  const logging = new Logging({projectId});

  // Selects the log to write to
  const log = logging.log(logName);

  // The data to write to the log
  const text = 'Hello, world!';

  // The metadata associated with the entry
  const metadata = {
    resource: {type: 'global'},
    // See: https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry#logseverity
    severity: 'INFO',
  };

  // Prepares a log entry
  const entry = log.entry(metadata, text);

  async function writeLog() {
    // Writes the log entry
    await log.write(entry);
    console.log(`Logged: ${text}`);
  }
  writeLog();
}

Batching Writes

High throughput applications should avoid awaiting calls to the logger:

await log.write(logEntry1);
await log.write(logEntry2);

Rather, applications should use a fire and forget approach:

log.write(logEntry1);
log.write(logEntry2);

The @google-cloud/logging library will handle batching and dispatching these log lines to the API.

Writing to Stdout

The LogSync class helps users easily write context-rich structured logs to stdout or any custom transport. It extracts additional log properties like trace context from HTTP headers and can be used as an on/off toggle between writing to the API or to stdout during local development.

Logs written to stdout are then picked up, out-of-process, by a Logging agent in the respective GCP environment. Logging agents can add more properties to each entry before streaming it to the Logging API.

Read more about Logging agents.

Serverless applications like Cloud Functions, Cloud Run, and App Engine are highly recommended to use the LogSync class as async logs may be dropped due to lack of CPU.

Read more about structured logging.

// Optional: Create and configure a client
const logging = new Logging();
await logging.setProjectId()
await logging.setDetectedResource()

// Create a LogSync transport, defaulting to `process.stdout`
const log = logging.logSync(logname);
const meta = { // optional field overrides here };
const entry = log.entry(meta, 'Your log message');
log.write(entry);

// Syntax sugar for logging at a specific severity
log.alert(entry);
log.warning(entry);

Samples

Samples are in the samples/ directory. Each sample's README.md has instructions for running its sample.

SampleSource CodeTry it
Fluentsource codeOpen in Cloud Shell
Log HTTP Requestsource codeOpen in Cloud Shell
Logssource codeOpen in Cloud Shell
Quickstartsource codeOpen in Cloud Shell
Sinkssource codeOpen in Cloud Shell

The Cloud Logging Node.js Client API Reference documentation also contains samples.

Supported Node.js Versions

Our client libraries follow the Node.js release schedule. Libraries are compatible with all current active and maintenance versions of Node.js.

Client libraries targeting some end-of-life versions of Node.js are available, and can be installed via npm dist-tags. The dist-tags follow the naming convention legacy-(version).

Legacy Node.js versions are supported as a best effort:

  • Legacy versions will not be tested in continuous integration.
  • Some security patches may not be able to be backported.
  • Dependencies will not be kept up-to-date, and features will not be backported.

Legacy tags available

  • legacy-8: install client libraries from this dist-tag for versions compatible with Node.js 8.

Versioning

This library follows Semantic Versioning.

This library is considered to be General Availability (GA). This means it is stable; the code surface will not change in backwards-incompatible ways unless absolutely necessary (e.g. because of critical security issues) or with an extensive deprecation period. Issues and requests against GA libraries are addressed with the highest priority.

More Information: Google Cloud Platform Launch Stages

Contributing

Contributions welcome! See the Contributing Guide.

Please note that this README.md, the samples/README.md, and a variety of configuration files in this repository (including .nycrc and tsconfig.json) are generated from a central template. To edit one of these files, make an edit to its template in this directory.

License

Apache Version 2.0

See LICENSE