log4js-node/lib/appenders/file.js

'use strict';

const debug = require('debug')('log4js:file');
const layouts = require('../layouts');
const path = require('path');
const streams = require('streamroller');
const os = require('os');

const eol = os.EOL || '\n';
const openFiles = [];

// close open files on process exit.
process.on('exit', () => {
  debug('Exit handler called.');
  openFiles.forEach((file) => {
    file.end();
  });
});

// On SIGHUP, close and reopen all files. This allows this appender to work with
// logrotate. Note that if you are using logrotate, you should not set
// `logSize`.
process.on('SIGHUP', () => {
  debug('SIGHUP handler called.');
  openFiles.forEach((writer) => {
    writer.closeTheStream(writer.openTheStream.bind(writer));
  });
});

/**
 * File Appender writing the logs to a text file. Supports rolling of logs by size.
 *
 * @param file file log messages will be written to
 * @param layout a function that takes a logEvent and returns a string
 *   (defaults to basicLayout).
 * @param logSize - the maximum size (in bytes) for a log file,
 *   if not provided then logs won't be rotated.
 * @param numBackups - the number of log files to keep after logSize
 *   has been reached (default 5)
 * @param options - options to be passed to the underlying stream
 * @param timezoneOffset - optional timezone offset in minutes (default system local)
 */
function fileAppender(file, layout, logSize, numBackups, options, timezoneOffset) {
  file = path.normalize(file);
  layout = layout || layouts.basicLayout;
  numBackups = numBackups === undefined ? 5 : numBackups;
  // there has to be at least one backup if logSize has been specified
  numBackups = numBackups === 0 ? 1 : numBackups;

  debug('Creating file appender (',
    file, ', ',
    logSize, ', ',
    numBackups, ', ',
    options, ', ',
    timezoneOffset, ')'
  );
  const writer = openTheStream(file, logSize, numBackups, options);

  // push file to the stack of open handlers
  openFiles.push(writer);

  return function (loggingEvent) {
    writer.write(layout(loggingEvent, timezoneOffset) + eol, 'utf8');
  };
}

function openTheStream(file, fileSize, numFiles, options) {
  const stream = new streams.RollingFileStream(
    file,
    fileSize,
    numFiles,
    options
  );
  stream.on('error', (err) => {
    console.error('log4js.fileAppender - Writing to file %s, error happened ', file, err);
  });
  return stream;
}


function configure(config, options) {
  let layout;
  if (config.layout) {
    layout = layouts.layout(config.layout.type, config.layout);
  }

  if (options && options.cwd && !config.absolute) {
    config.filename = path.join(options.cwd, config.filename);
  }

  return fileAppender(
    config.filename,
    layout,
    config.maxLogSize,
    config.backups,
    config,
    config.timezoneOffset
  );
}

function shutdown(cb) {
  let completed = 0;
  let error;
  const complete = (err) => {
    error = error || err;
    completed++; // eslint-disable-line no-plusplus
    if (completed >= openFiles.length) {
      cb(error);
    }
  };
  if (!openFiles.length) {
    return cb();
  }

  return openFiles.forEach((file) => {
    if (!file.write(eol, 'utf-8')) {
      file.once('drain', () => {
        file.end(complete);
      });
    } else {
      file.end(complete);
    }
  });
}

module.exports.appender = fileAppender;
module.exports.configure = configure;
module.exports.shutdown = shutdown;