pino-tee  
Tee pino logs into multiple files, according to the given levels. Works with any newline delimited json stream.
Install
npm i pino-tee -gUsage
CLI
The following writes the log output of app.js to ./all-logs, while
writing only warnings and errors to `./warn-log:
node app.js | pino-tee warn ./warn-logs > ./all-logsNodeJS
You can log to multiple files by spawning a child process:
const pino = require('pino');
const childProcess = require('child_process');
const stream = require('stream');
// Environment variables
const cwd = process.cwd();
const {env} = process;
const logPath = `${cwd}/log`;
// Create a stream where the logs will be written
const logThrough = new stream.PassThrough();
const log = pino({name: 'project'}, logThrough);
// Log to multiple files using a separate process
const child = childProcess.spawn(process.execPath, [
require.resolve('pino-tee'),
'warn', `${logPath}/warn.log`,
'error', `${logPath}/error.log`,
'fatal', `${logPath}/fatal.log`
], {cwd, env});
logThrough.pipe(child.stdin);
// Log pretty messages to console (optional, for development purposes only)
const pretty = pino.pretty();
pretty.pipe(process.stdout);
logThrough.pipe(pretty);API
pinoTee(source)
Create a new tee instance from source. It is an extended instance of
cloneable-readable.
Example:
const tee = require('pino-tee')
const fs = require('fs')
const stream = tee(process.stdin)
stream.tee(fs.createWriteStream('errors'), line => line.level >= 50)
stream.pipe(process.stdout)stream.tee(dest, [filter])
Create a new stream that will filter a given line based on some parameters. Each line is automatically parsed, or skipped if it is not a newline delimited json.
The filter can be a function with signature filter(line), where
line is a parsed JSON object. The filter can also be one of the
pino levels either
as text or as a custom level number, in that case all log lines with
that level or greater will be written.
Acknowledgements
This project was kindly sponsored by nearForm.
License
MIT
