streamroller

node.js file streams that roll over when they reach a maximum size, or a date/time.

    npm install streamroller

usage

    var rollers = require('streamroller');
    var stream = new rollers.RollingFileStream('myfile', 1024, 3);
    stream.write("stuff");
    stream.end();

The streams behave the same as standard node.js streams, except that when certain conditions are met they will rename the current file to a backup and start writing to a new file.

new RollingFileStream(filename [, maxSize, numBackups, options])

• filename (String)
• maxSize - the size in bytes to trigger a rollover, if not provided this defaults to MAX_SAFE_INTEGER and the stream will not roll.
• numBackups - the number of old files to keep
• options - Object
  • encoding - defaults to 'utf8'
  • mode - defaults to 0644
  • flags - defaults to 'a' (see fs.open for more details)
  • compress - (boolean) defaults to false - compress the backup files using gzip (files will have .gz extension).
  • keepFileExt - (boolean) defaults to false - keep the file original extension. e.g.: abc.log -> abc.1.log.

This returns a WritableStream. When the current file being written to (given by filename) gets up to or larger than maxSize, then the current file will be renamed to filename.1 and a new file will start being written to. Up to numBackups of old files are maintained, so if numBackups is 3 then there will be 4 files:

     filename
     filename.1
     filename.2
     filename.3

When filename size >= maxSize then:

     filename -> filename.1
     filename.1 -> filename.2
     filename.2 -> filename.3
     filename.3 gets overwritten
     filename is a new file

new DateRollingFileStream(filename, pattern, options)

• filename (String)
• pattern (String) - the date pattern to trigger rolling (see below)
• options - Object
  • encoding - defaults to 'utf8'
  • mode defaults to 0644
  • flags defaults to 'a' (see fs.open for more details)
  • compress - (boolean) compress the backup files, defaults to false
  • keepFileExt - (boolean) defaults to false - keep the file original extension. e.g.: abc.log -> abc.2013-08-30.log.
  • alwaysIncludePattern - (boolean) extend the initial file with the pattern, defaults to false
  • daysToKeep - (integer) if this is greater than 0, then files older than daysToKeep days will be deleted during file rolling.

This returns a WritableStream. When the current time, formatted as pattern, changes then the current file will be renamed to filename.formattedDate where formattedDate is the result of processing the date through the pattern, and a new file will begin to be written. Streamroller uses date-format to format dates, and the pattern should use the date-format format. e.g. with a pattern of ".yyyy-MM-dd", and assuming today is August 29, 2013 then writing to the stream today will just write to filename. At midnight (or more precisely, at the next file write after midnight), filename will be renamed to filename.2013-08-29 and a new filename will be created. If options.alwaysIncludePattern is true, then the initial file will be filename.2013-08-29 and no renaming will occur at midnight, but a new file will be written to with the name filename.2013-08-30.