rotating-file-stream
Advanced tools
Opens a stream.Writable to a file rotated by interval and/or size. A logrotate alternative.
The rotating-file-stream npm package is used to create a stream that writes to a file and rotates the file based on a specified condition, such as file size or time interval. This is particularly useful for logging purposes where you want to manage log file sizes and avoid having a single, ever-growing log file.
Time-based rotation
This feature allows you to rotate the log file based on a time interval. In this example, the log file 'access.log' will be rotated daily and stored in the '/var/log' directory.
const rfs = require('rotating-file-stream');
const stream = rfs.createStream('access.log', {
interval: '1d', // rotate daily
path: '/var/log'
});Size-based rotation
This feature allows you to rotate the log file based on its size. In this example, the log file 'access.log' will be rotated every time it reaches 10MB and stored in the '/var/log' directory.
const rfs = require('rotating-file-stream');
const stream = rfs.createStream('access.log', {
size: '10M', // rotate every 10 MegaBytes written
path: '/var/log'
});Compression
This feature allows you to compress the rotated log files. In this example, the log file 'access.log' will be rotated daily and compressed using gzip, then stored in the '/var/log' directory.
const rfs = require('rotating-file-stream');
const stream = rfs.createStream('access.log', {
interval: '1d', // rotate daily
compress: 'gzip', // compress rotated files
path: '/var/log'
});Custom rotation
This feature allows you to specify a custom rotation policy. In this example, the log file 'access.log' will be rotated and up to 7 rotated files will be kept in the '/var/log' directory.
const rfs = require('rotating-file-stream');
const stream = rfs.createStream('access.log', {
rotate: 7, // keep 7 rotated files
path: '/var/log'
});The winston-daily-rotate-file package is a transport for the winston logging library that allows you to rotate log files based on a time interval. It is similar to rotating-file-stream in that it supports time-based rotation and compression, but it is specifically designed to work with the winston logging library.
The logrotate-stream package provides a writable stream that rotates log files based on size or time. It is similar to rotating-file-stream in terms of functionality, but it offers a simpler API and fewer configuration options.
The file-stream-rotator package is another option for rotating log files based on size or time. It offers similar features to rotating-file-stream, including time-based and size-based rotation, as well as compression. However, it is less actively maintained compared to rotating-file-stream.
var rfs = require('rotating-file-stream');
var stream = rfs('file.log', {
size: '10M', // rotate every 10 MegaBytes written
interval: '1d', // rotate daily
compress: 'gzip' // compress rotated files
});
This package is currently under development.
Please check the TODO list to be aware of what is missing.
With npm:
npm install rotating-file-stream
Returns a new stream.Writable to filename as fs.createWriteStream does. The file is rotated following options rules.
The most complex problem about file name is: "how to call the rotated file name?"
The answer to this question may vary in many forms depending on application requirements and/or specifications. If there are no requirements, a String can be used and default rotated file name generator will be used; otherwise a Function which returns the rotated file name can be used.
An example of a complex rotated file name generator function could be:
function pad(num) {
return (num > 9 ? "" : "0") + num;
}
function generator(time, index) {
if(! time)
return "file.log";
var month = time.getFullYear() + "" + pad(time.getMonth() + 1);
var day = pad(time.getDate());
var hour = pad(time.getHours());
var minute = pad(time.getMinutes());
return "/storage/" + month + "/" +
month + day + "-" + hour + minute + "-" + index + "-" + filename;
}
var rfs = require('rotating-file-stream');
var stream = rfs(generator, {
size: '10M',
interval: '1d'
});
Note: If part of returned destination path does not exists, the rotation job will try to create it.
Accepts a positive integer followed by one of these possible letters:
size: '300B', // rotates the file when its size exceeds 300 Bytes
// useful for tests
size: '300K', // rotates the file when its size exceeds 300 KiloBytes
size: '100M', // rotates the file when its size exceeds 100 MegaBytes
size: '1G', // rotates the file when its size exceeds a GigaByte
Accepts a positive integer followed by one of these possible letters:
interval: '5s', // rotates the file at seconds 0, 5, 10, 15 and so on
// useful for tests
interval: '5m', // rotates the file at minutes 0, 5, 10, 15 and so on
interval: '2h', // rotates the file at midnight, 02:00, 04:00 and so on
interval: '1d', // rotates the file at every midnight
Due the nature of Node.js compression may be done with an external command (to use other CPUs than the one used by Node.js to not subtract CPU power to our application) or with internal code (to use the CPU used by Node.js to not subtract more CPU power than expected to the system). This decision is left to you.
Following fixed strings are allowed to compress the files with internal libraries:
To enable external compression, a function can be used or simple the boolean true value to use default external compression. The function should accept source and dest file names and must return the shell command to be executed to archive the file. The two following code snippets have exactly the same effect:
var rfs = require('rotating-file-stream');
var stream = rfs('file.log', {
size: '10M',
compress: true
});
var rfs = require('rotating-file-stream');
var stream = rfs('file.log', {
size: '10M',
compress: function(source, dest) {
return "cat " + source + " | gzip -t9 > " + dest;
}
});
Note: The shell command to archive the rotated file should not remove the source file, it will be removed by the package if archive job complete with success.
Custom Events are emitted by the stream.
var rfs = require('rotating-file-stream');
var stream = rfs(...);
stream.on('error', function(err) {
// here are reported errors occurred while rotating as well write errors
});
stream.on('rotation', function() {
// rotation job started
});
stream.on('rotated', function(filename) {
// rotation job completed with success and produced given filename
});
Regardless of when and why rotation happens, the content of a single stream.write will never be split among two files.
Once the no rotated file is opened first time, its size is checked and if it is greater or equal to size limit, a first rotation happens. After each stream.write, the same check is performed.
The package sets a Timeout to start a rotation job at the right moment.
Logs should be handled so carefully, so this package tries to never overwrite files.
At stream creation, if the not rotated log file already exists and its size exceeds the rotation size, an initial rotation attempt is done.
At each rotation attempt a check is done to verify that destination rotated file does not exists yet; if this is not the case a new destination rotated file name is generated and the same check is performed before going on. This is repeated until a not existing destination file name is found or the package is exhausted. For this reason the rotated file name generator function may be called several times for each rotation job.
Once an error event is emitted, nothing more can be done: the stream is closed as well.
This package is written following Node.js 4.0 specifications always taking care about backward compatibility. The package it tested under following versions:
Do not hesitate to report any bug or inconsistency @github.
FAQs
Opens a stream.Writable to a file rotated by interval and/or size. A logrotate alternative.
We found that rotating-file-stream demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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