logger.go

// Copyright (c) 2017 Intel Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"log/syslog"
	"time"

	"github.com/sirupsen/logrus"
	lSyslog "github.com/sirupsen/logrus/hooks/syslog"
)

// sysLogHook wraps a syslog logrus hook and a formatter to be used for all
// syslog entries.
//
// This is necessary to allow the main logger (for "--log=") to use a custom
// formatter ("--log-format=") whilst allowing the system logger to use a
// different formatter.
type sysLogHook struct {
	shook     *lSyslog.SyslogHook
	formatter logrus.Formatter
}

func (h *sysLogHook) Levels() []logrus.Level {
	return h.shook.Levels()
}

// Fire is responsible for adding a log entry to the system log. It switches
// formatter before adding the system log entry, then reverts the original log
// formatter.
func (h *sysLogHook) Fire(e *logrus.Entry) (err error) {
	formatter := e.Logger.Formatter

	e.Logger.Formatter = h.formatter

	err = h.shook.Fire(e)

	e.Logger.Formatter = formatter

	return err
}

func newSystemLogHook(network, raddr string) (*sysLogHook, error) {
	hook, err := lSyslog.NewSyslogHook(network, raddr, syslog.LOG_INFO, name)
	if err != nil {
		return nil, err
	}

	return &sysLogHook{
		formatter: &logrus.TextFormatter{
			TimestampFormat: time.RFC3339Nano,
		},
		shook: hook,
	}, nil
}

// handleSystemLog sets up the system-level logger.
func handleSystemLog(network, raddr string) error {
	hook, err := newSystemLogHook(network, raddr)
	if err != nil {
		return err
	}

	ccLog.Logger.Hooks.Add(hook)

	return nil
}