logrusrotate

This package can be used with logrus to add effortless log rotation support to your long-running daemon.

Why [this package was created]

Task requirements:

yourapp.log should always refer to the actual log (which you should be able to tail using tail -f yourapp.log)
periodically (or after size threshold is reached) this log file needs to be archived (copied to a name with a suffix)
all currently executing log.XXX calls should successfully finish writing to the file being rotated

How [this module takes a different approach to log file 'rotation']

When creating a log file, New() also creates another entry (logname.) as a hardlink to the logname. Each time the rotation happens, a new file with the suffix is first created, log.SetOutput is called, and logname is re-linked to point to the same file.

Suffix format

This can either be one of the time formats, or a string, which must parse to integer 8 (you can figure out, why).

Example

// main.go
import "logrusrotate"

const logBaseName = "/path/to/yourapp.log"

var log *logrus.Logger

func startLogrotate(log *ruslog.Logger) {
	rotateInterval := 1 * logrusrotate.Hour // .Second, .Minute, .Hour, .Day
	rotateMb := 100 // not currently used
	suffixFormat := "20060102_150405"

	logrusrotate.New(log, logBaseName, rotateInterval, rotateMb, suffixFormat)
}

func main() {
	log = logrus.New()
	startLogrotate(log)
}

API

logrusrotate.New()

Creates a rotator instance, which runs Start() immediately.

	rotator := logrusrotate.New(...)

rotator.Start()

Re-starts a previously stopped rotation.

rotator.Stop()

Disables the rotation

rotator.Rotate(suffixTime time.Time)

Forces the immediate log rotation. The rotation timer is restarted. If the argument is 0 (e.g. time.UnixMicro(0)), time.Now() is used instead.

rotator.SetVerbose(bool)

Verbosity adds a corresponding line to the log when the file is rotated periodically or forcefully.

TODO

rotation by size is not implemented
sequential formats do not respect zero-prefixed suffixes (e.g. "0008" is treated the same as "8")

maard/logrusrotate