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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2014-2015 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package logger
import (
"fmt"
"io"
"io/ioutil"
"log"
"log/syslog"
"os"
"sync"
)
// A Logger is a fairly minimal logging tool.
type Logger interface {
// Notice is for messages that the user should see
Notice(msg string)
// Debug is for messages that the user should be able to find if they're debugging something
Debug(msg string)
}
const (
// DefaultFlags are passed to the default console log.Logger
DefaultFlags = log.Ldate | log.Ltime | log.Lmicroseconds | log.Lshortfile
// SyslogFlags are passed to the default syslog log.Logger
SyslogFlags = log.Lshortfile
// SyslogPriority for the default syslog log.Logger
SyslogPriority = syslog.LOG_DEBUG | syslog.LOG_USER
)
type nullLogger struct{}
func (nullLogger) Notice(string) {}
func (nullLogger) Debug(string) {}
// NullLogger is a logger that does nothing
var NullLogger = nullLogger{}
var (
logger Logger = NullLogger
lock sync.Mutex
)
// Panicf notifies the user and then panics
func Panicf(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
lock.Lock()
defer lock.Unlock()
logger.Notice("PANIC " + msg)
panic(msg)
}
// Noticef notifies the user of something
func Noticef(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
lock.Lock()
defer lock.Unlock()
logger.Notice(msg)
}
// Debugf records something in the debug log
func Debugf(format string, v ...interface{}) {
msg := fmt.Sprintf(format, v...)
lock.Lock()
defer lock.Unlock()
logger.Debug(msg)
}
// SetLogger sets the global logger to the given one
func SetLogger(l Logger) {
lock.Lock()
defer lock.Unlock()
logger = l
}
// ConsoleLog sends Notices to a log.Logger and Debugs to syslog
type ConsoleLog struct {
log *log.Logger
sys *log.Logger
}
// Debug sends the msg to syslog
func (l *ConsoleLog) Debug(msg string) {
l.sys.Output(3, "DEBUG: "+msg)
}
// Notice alerts the user about something, as well as putting it syslog
func (l *ConsoleLog) Notice(msg string) {
l.sys.Output(3, msg)
l.log.Output(3, msg)
}
// variable to allow mocking the syslog.NewLogger call in the tests
var newSyslog = newSyslogImpl
func newSyslogImpl() (*log.Logger, error) {
return syslog.NewLogger(SyslogPriority, SyslogFlags)
}
// NewConsoleLog creates a ConsoleLog with a log.Logger using the given
// io.Writer and flag, and a syslog.Writer.
func NewConsoleLog(w io.Writer, flag int) (*ConsoleLog, error) {
clog := log.New(w, "", flag)
sys, err := newSyslog()
if err != nil {
clog.Output(3, "WARNING: can not create syslog logger")
sys = log.New(ioutil.Discard, "", flag)
}
return &ConsoleLog{
log: clog,
sys: sys,
}, nil
}
// SimpleSetup creates the default (console) logger
func SimpleSetup() error {
l, err := NewConsoleLog(os.Stderr, DefaultFlags)
if err != nil {
return err
}
SetLogger(l)
return nil
}
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