coredns/middleware/roller.go

package middleware

import (
	"io"
	"strconv"

	"github.com/mholt/caddy"
	"gopkg.in/natefinch/lumberjack.v2"
)

func ParseRoller(c *caddy.Controller) (*LogRoller, error) {
	var size, age, keep int
	// This is kind of a hack to support nested blocks:
	// As we are already in a block: either log or errors,
	// c.nesting > 0 but, as soon as c meets a }, it thinks
	// the block is over and return false for c.NextBlock.
	for c.NextBlock() {
		what := c.Val()
		if !c.NextArg() {
			return nil, c.ArgErr()
		}
		value := c.Val()
		var err error
		switch what {
		case "size":
			size, err = strconv.Atoi(value)
		case "age":
			age, err = strconv.Atoi(value)
		case "keep":
			keep, err = strconv.Atoi(value)
		}
		if err != nil {
			return nil, err
		}
	}
	return &LogRoller{
		MaxSize:    size,
		MaxAge:     age,
		MaxBackups: keep,
		LocalTime:  true,
	}, nil
}

// LogRoller implements a middleware that provides a rolling logger.
type LogRoller struct {
	Filename   string
	MaxSize    int
	MaxAge     int
	MaxBackups int
	LocalTime  bool
}

// GetLogWriter returns an io.Writer that writes to a rolling logger.
func (l LogRoller) GetLogWriter() io.Writer {
	return &lumberjack.Logger{
		Filename:   l.Filename,
		MaxSize:    l.MaxSize,
		MaxAge:     l.MaxAge,
		MaxBackups: l.MaxBackups,
		LocalTime:  l.LocalTime,
	}
}