Bunyan と Express

Node.js Express アプリケーションで Cloud Logging を使用して、Bunyan を設定、使用する方法を紹介します。

コードサンプル

Node.js

Logging 用のクライアントライブラリをインストールして使用する方法については、Logging クライアントライブラリをご覧ください。

// 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();