telegraf/logger/logger.go

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package logger
import (
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"errors"
"io"
"log"
"os"
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"regexp"
"time"
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"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/internal/rotate"
"github.com/influxdata/wlog"
)
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var prefixRegex = regexp.MustCompile("^[DIWE]!")
const (
LogTargetFile = "file"
LogTargetStderr = "stderr"
)
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// LogConfig contains the log configuration settings
type LogConfig struct {
// will set the log level to DEBUG
Debug bool
//will set the log level to ERROR
Quiet bool
//stderr, stdout, file or eventlog (Windows only)
LogTarget string
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// will direct the logging output to a file. Empty string is
// interpreted as stderr. If there is an error opening the file the
// logger will fallback to stderr
Logfile string
// will rotate when current file at the specified time interval
RotationInterval internal.Duration
// will rotate when current file size exceeds this parameter.
RotationMaxSize internal.Size
// maximum rotated files to keep (older ones will be deleted)
RotationMaxArchives int
}
type LoggerCreator interface {
CreateLogger(config LogConfig) (io.Writer, error)
}
var loggerRegistry map[string]LoggerCreator
func registerLogger(name string, loggerCreator LoggerCreator) {
if loggerRegistry == nil {
loggerRegistry = make(map[string]LoggerCreator)
}
loggerRegistry[name] = loggerCreator
}
type telegrafLog struct {
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writer io.Writer
internalWriter io.Writer
}
func (t *telegrafLog) Write(b []byte) (n int, err error) {
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var line []byte
if !prefixRegex.Match(b) {
line = append([]byte(time.Now().UTC().Format(time.RFC3339)+" I! "), b...)
} else {
line = append([]byte(time.Now().UTC().Format(time.RFC3339)+" "), b...)
}
return t.writer.Write(line)
}
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func (t *telegrafLog) Close() error {
var stdErrWriter io.Writer
stdErrWriter = os.Stderr
// avoid closing stderr
if t.internalWriter != stdErrWriter {
closer, isCloser := t.internalWriter.(io.Closer)
if !isCloser {
return errors.New("the underlying writer cannot be closed")
}
return closer.Close()
}
return nil
}
// newTelegrafWriter returns a logging-wrapped writer.
func newTelegrafWriter(w io.Writer) io.Writer {
return &telegrafLog{
writer: wlog.NewWriter(w),
internalWriter: w,
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}
}
// SetupLogging configures the logging output.
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func SetupLogging(config LogConfig) {
newLogWriter(config)
}
type telegrafLogCreator struct {
}
func (t *telegrafLogCreator) CreateLogger(config LogConfig) (io.Writer, error) {
var writer, defaultWriter io.Writer
defaultWriter = os.Stderr
switch config.LogTarget {
case LogTargetFile:
if config.Logfile != "" {
var err error
if writer, err = rotate.NewFileWriter(config.Logfile, config.RotationInterval.Duration, config.RotationMaxSize.Size, config.RotationMaxArchives); err != nil {
log.Printf("E! Unable to open %s (%s), using stderr", config.Logfile, err)
writer = defaultWriter
}
} else {
log.Print("E! Empty logfile, using stderr")
writer = defaultWriter
}
case LogTargetStderr, "":
writer = defaultWriter
default:
log.Printf("E! Unsupported logtarget: %s, using stderr", config.LogTarget)
writer = defaultWriter
}
return newTelegrafWriter(writer), nil
}
// Keep track what is actually set as a log output, because log package doesn't provide a getter.
// It allows closing previous writer if re-set and have possibility to test what is actually set
var actualLogger io.Writer
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func newLogWriter(config LogConfig) io.Writer {
log.SetFlags(0)
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if config.Debug {
wlog.SetLevel(wlog.DEBUG)
}
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if config.Quiet {
wlog.SetLevel(wlog.ERROR)
}
if !config.Debug && !config.Quiet {
wlog.SetLevel(wlog.INFO)
}
var logWriter io.Writer
if logCreator, ok := loggerRegistry[config.LogTarget]; ok {
logWriter, _ = logCreator.CreateLogger(config)
}
if logWriter == nil {
logWriter, _ = (&telegrafLogCreator{}).CreateLogger(config)
}
if closer, isCloser := actualLogger.(io.Closer); isCloser {
closer.Close()
}
log.SetOutput(logWriter)
actualLogger = logWriter
return logWriter
}
func init() {
tlc := &telegrafLogCreator{}
registerLogger("", tlc)
registerLogger(LogTargetStderr, tlc)
registerLogger(LogTargetFile, tlc)
}