stackdriver-logging-winston-koa
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Koa middleware for Winston transport to Cloud Logging
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Markdown
[](https://badge.fury.io/js/stackdriver-logging-winston-koa)
[](https://codecov.io/gh/toolsplus/stackdriver-logging-winston-koa)
This module provides an [Koa](https://koajs.com) middleware for working with [Stackdriver Logging](https://cloud.google.com/logging/docs),
compatible with [Winston](https://www.npmjs.com/package/winston).
The implementation is adapted from the existing express middleware implementation
in [nodejs-logging-winston](https://github.com/googleapis/nodejs-logging-winston) module.
For general documentation on winston logging to Stackdriver please refer to the
[](https://github.com/googleapis/nodejs-logging-winston) module.
```bash
npm install stackdriver-logging-winston-koa
```
We provide a middleware that can be used in an koa application. Apart from
being easy to use, this enables some more powerful features of Stackdriver
Logging: request bundling. Any application logs emitted on behalf of a specific
request will be shown nested inside the request log.
The middleware adds a `winston`-style log function to the `ctx` object. You
can use this wherever you have access to the `ctx` object. All log entries that
are made on behalf of a specific request are shown bundled together in the
Stackdriver Logging UI.
```javascript
const lw = require('stackdriver-logging-winston-koa');
const winston = require('winston');
// Import koa module and create an http server.
const koa = require('koa');
const logger = winston.createLogger();
async function startServer() {
// Create a middleware that will use the provided logger.
// A Stackdriver Logging transport will be created automatically
// and added onto the provided logger.
const mw = await lw.koa.makeMiddleware(logger);
// Alternatively, you can construct a LoggingWinston transport
// yourself and pass it int.
// const transport = new LoggingWinston({...});
// const mw = await lw.koa.makeMiddleware(logger, transport);
const app = koa();
// Install the logging middleware. This ensures that a Winston-style `log`
// function is available on the `context` object. Attach this as one of the
// earliest middleware to make sure that log function is available in all the
// subsequent middleware and routes.
app.use(mw);
// Setup an http route and a route handler.
app.use(async (ctx) => {
// `ctx.log` can be used as a winston style log method. All logs generated
// using `ctx.log` use the current request context. That is, all logs
// corresponding to a specific request will be bundled in the Stackdriver
// UI.
ctx.log.info('this is an info log message');
ctx.body = 'hello world';
});
// `logger` can be used as a global logger, one not correlated to any specific
// request.
logger.info('bonjour');
// Start listening on the http server.
app.listen(8080, () => {
console.log('http server listening on port 8080');
});
}
startServer();
```
Contributions welcome!
Apache Version 2.0