gocommon/log/hooks/file/hook.go

package file

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"time"

	"github.com/juju/errors"
	"github.com/sirupsen/logrus"

	rotatelogs "github.com/lestrrat-go/file-rotatelogs"
)

// NewHook will create a File Hook for logrus.
func NewHook(c *ConfigStruct) (logrus.Hook, error) {

	err := c.IsValid()
	if err != nil {
		return nil, errors.Trace(err)
	}

	outputFormat := OutputFormat_TEXT
	if c.OutputFormat != nil {
		outputFormat = OutputFormat(*c.OutputFormat)
	}

	var w io.Writer
	if c.Rotate {
		rotateTime, _ := time.ParseDuration(*c.RotateTime)

		// let's construct log rotator options
		rotateOptions := []rotatelogs.Option{
			rotatelogs.WithLinkName(c.Filename),
			rotatelogs.WithRotationTime(rotateTime),
		}

		if c.RotateMaxAge != nil {
			rotateMaxAge, _ := time.ParseDuration(*c.RotateMaxAge)
			rotateOptions = append(rotateOptions, rotatelogs.WithMaxAge(rotateMaxAge))
		} else if c.RotateMaxFile != nil {
			rotateOptions = append(
				rotateOptions,
				rotatelogs.WithRotationCount(uint(*c.RotateMaxFile)),
				rotatelogs.WithMaxAge(-1),
			)
		}

		w, err = rotatelogs.New(
			fmt.Sprintf("%s.%%Y%%m%%d%%H%%M", c.Filename),
			rotateOptions...,
		)
		if err != nil {
			return nil, errors.Trace(err)
		}

	} else {
		dirname := filepath.Dir(c.Filename)
		if err := os.MkdirAll(dirname, 0750); err != nil {
			return nil, errors.NewNotSupported(err, fmt.Sprintf("failed to create directory %s", dirname))
		}

		// if we got here, then we need to create a file
		fh, err := os.OpenFile(c.Filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
		if err != nil {
			return nil, errors.NewNotSupported(err, fmt.Sprintf("failed to open file %s", c.Filename))
		}

		w = fh
	}

	h := NewAsyncFileHook(w, handleFormat(outputFormat))

	return h, nil
}

// handleFormat will take a OutputFormat and will transform it in a formatter.
func handleFormat(of OutputFormat) logrus.Formatter {

	if of == OutputFormat_JSON {
		return &logrus.JSONFormatter{
			PrettyPrint:     false,
			TimestampFormat: time.RFC3339Nano,
		}
	}

	return &logrus.TextFormatter{
		DisableColors:    true,
		TimestampFormat:  time.RFC3339Nano,
		QuoteEmptyFields: true,
	}
}