bunyan-rotating-file-stream

Bunyan is a simple and fast JSON logging library for node.js services: Bunyan Rotating File Stream is an improved rotating file stream component that has some extra features

    new RotatingFileStream({
        path: '/var/log/foo.log',
        period: '1d',   // daily rotation
        totalFiles: 3   // keep at most 3 back copies
    });

Current Status

The basics of the features are there, you should be able to use the rotating file logging to limit of disk space usage while maximising the amount of logs kept.

As ever, there's a lot more features to add as well as a number of gaurantees to make.

Installation

npm install bunyan-rotating-file-stream

Features

• Rotate to a new log file periodically
• Rotate to a new log file once the main log file goes over a certain size
• Keep a maximum number of archival log files
• Delete older log files once the archive reaches a certain size
• GZip archived log files

stream type: rotating-file

WARNING on node 0.8 usage: Users of Bunyan's rotating-file should (a) be using at least bunyan 0.23.1 (with the fix for this issue), and (b) should use at least node 0.10 (node 0.8 does not support the unref() method on setTimeout(...) needed for the mentioned fix). The symptom is that process termination will hang for up to a full rotation period.

WARNING on cluster usage: Using Bunyan's rotating-file stream with node.js's "cluster" module can result in unexpected file rotation. You must not have multiple processes in the cluster logging to the same file path. In other words, you must have a separate log file path for the master and each worker in the cluster. Alternatively, consider using a system file rotation facility such as logrotate on Linux or logadm on SmartOS/Illumos. See this comment on issue #117 for details.

A type === 'raw' is a file stream that handles file automatic rotation.

var log = bunyan.createLogger({
    name: 'foo',
    streams: [{
        type: 'raw',
        stream: new RotatingFileStream({
            path: '/var/log/foo.log',
            period: '1d',   // daily rotation
            totalFiles: 3        // keep 3 back copies
        })
    }]
});

This will rotate '/var/log/foo.log' every day (at midnight) to:

/var/log/foo.log.0     # yesterday
/var/log/foo.log.1     # 1 day ago
/var/log/foo.log.2     # 2 days ago

Currently, there is no support for providing a template for the rotated files, or for rotating when the log reaches a threshold size.

Field	Required?	Default	Description
path	Yes	-	A file path to which to log. Rotated files will be "$path.0", "$path.1", ...
period	No	1d	The period at which to rotate. This is a string of the format "$number$scope" where "$scope" is one of "ms" (milliseconds -- only useful for testing), "h" (hours), "d" (days), "w" (weeks), "m" (months), "y" (years). Or one of the following names can be used "hourly" (means 1h), "daily" (1d), "weekly" (1w), "monthly" (1m), "yearly" (1y). Rotation is done at the start of the scope: top of the hour (h), midnight (d), start of Sunday (w), start of the 1st of the month (m), start of Jan 1st (y).
threshold	0	0	The maximum size for a log file to reach before it's rotated. Can be specified as a number of bytes, or a more friendly unit: eg, '100k', '1m', '2g' etc.
totalFiles	No	0	The number of rotated files to keep. 0 to keep files regardless of how many there are.
totalSize	No	0	Delete older rotated files once the total size of rotated files reaches this size. 0 here keeps files regardless of how large they get.
gzip	No	false	Compress rotated files using gzip. Adds a '.gz' extension.

Note on log rotation: Often you may be using external log rotation utilities like logrotate on Linux or logadm on SmartOS/Illumos. In those cases, unless your are ensuring "copy and truncate" semantics (via copytruncate with logrotate or -c with logadm) then the fd for your 'file' stream will change. You can tell bunyan to reopen the file stream with code like this in your app:

var log = bunyan.createLogger(...);
...
process.on('SIGUSR2', function () {
    log.reopenFileStreams();
});

where you'd configure your log rotation to send SIGUSR2 (or some other signal) to your process. Any other mechanism to signal your app to run log.reopenFileStreams() would work as well.

The scheme I follow is most succinctly described by the bootstrap guys here.

tl;dr: All versions are <major>.<minor>.<patch> which will be incremented for breaking backward compat and major reworks, new features without breaking change, and bug fixes, respectively.

License

MIT. See "LICENSE.txt".

See Also

• Bunyan: https://github.com/trentm/node-bunyan.