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// RAINBOND, Application Management Platform
// Copyright (C) 2014-2019 Goodrain Co., Ltd.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version. For any non-GPL usage of Rainbond,
// one or multiple Commercial Licenses authorized by Goodrain Co., Ltd.
// must be obtained first.
// 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 (
"compress/gzip"
"context"
"encoding/json"
"fmt"
"io"
"os"
"runtime"
"strings"
"sync"
"time"
"github.com/docker/docker/pkg/pubsub"
"github.com/docker/docker/pkg/filenotify"
"github.com/docker/docker/pkg/pools"
"github.com/fsnotify/fsnotify"
"github.com/Sirupsen/logrus"
"github.com/docker/docker/daemon/logger/jsonfilelog/jsonlog"
"github.com/docker/docker/pkg/tailfile"
"github.com/pkg/errors"
)
const maxJSONDecodeRetry = 20000
const tmpLogfileSuffix = ".tmp"
// rotateFileMetadata is a metadata of the gzip header of the compressed log file
type rotateFileMetadata struct {
LastTime time.Time `json:"lastTime,omitempty"`
}
// refCounter is a counter of logfile being referenced
type refCounter struct {
mu sync.Mutex
counter map[string]int
}
// Reference increase the reference counter for specified logfile
func (rc *refCounter) GetReference(fileName string, openRefFile func(fileName string, exists bool) (*os.File, error)) (*os.File, error) {
rc.mu.Lock()
defer rc.mu.Unlock()
var (
file *os.File
err error
)
_, ok := rc.counter[fileName]
file, err = openRefFile(fileName, ok)
if err != nil {
return nil, err
}
if ok {
rc.counter[fileName]++
} else if file != nil {
rc.counter[file.Name()] = 1
}
return file, nil
}
// Dereference reduce the reference counter for specified logfile
func (rc *refCounter) Dereference(fileName string) error {
rc.mu.Lock()
defer rc.mu.Unlock()
rc.counter[fileName]--
if rc.counter[fileName] <= 0 {
delete(rc.counter, fileName)
err := os.Remove(fileName)
if err != nil {
return err
}
}
return nil
}
// GetTailReaderFunc is used to truncate a reader to only read as much as is required
// in order to get the passed in number of log lines.
// It returns the sectioned reader, the number of lines that the section reader
// contains, and any error that occurs.
type GetTailReaderFunc func(ctx context.Context, f SizeReaderAt, nLogLines int) (rdr io.Reader, nLines int, err error)
type makeDecoderFunc func(rdr io.Reader) func() (*Message, error)
type wrappedReaderAt struct {
io.ReaderAt
pos int64
}
func (r *wrappedReaderAt) Read(p []byte) (int, error) {
n, err := r.ReaderAt.ReadAt(p, r.pos)
r.pos += int64(n)
return n, err
}
func decodeLogLine(dec *json.Decoder, l *jsonlog.JSONLog) (*Message, error) {
l.Reset()
if err := dec.Decode(l); err != nil {
return nil, err
}
msg := &Message{
Source: l.Stream,
Timestamp: l.Created,
Line: []byte(l.Log),
Attrs: l.Attrs,
}
return msg, nil
}
// decodeFunc is used to create a decoder for the log file reader
func decodeFunc(rdr io.Reader) func() (*Message, error) {
l := &jsonlog.JSONLog{}
dec := json.NewDecoder(rdr)
return func() (msg *Message, err error) {
for retries := 0; retries < maxJSONDecodeRetry; retries++ {
msg, err = decodeLogLine(dec, l)
if err == nil || err == io.EOF {
break
}
// try again, could be due to a an incomplete json object as we read
if _, ok := err.(*json.SyntaxError); ok {
dec = json.NewDecoder(rdr)
continue
}
// io.ErrUnexpectedEOF is returned from json.Decoder when there is
// remaining data in the parser's buffer while an io.EOF occurs.
// If the json logger writes a partial json log entry to the disk
// while at the same time the decoder tries to decode it, the race condition happens.
if err == io.ErrUnexpectedEOF {
reader := io.MultiReader(dec.Buffered(), rdr)
dec = json.NewDecoder(reader)
continue
}
logrus.WithError(err).WithField("retries", retries).Warn("got error while decoding json")
}
return msg, err
}
}
func getTailReader(ctx context.Context, r SizeReaderAt, req int) (io.Reader, int, error) {
return tailfile.NewTailReader(ctx, r, req)
}
func newSectionReader(f *os.File) (*io.SectionReader, error) {
// seek to the end to get the size
// we'll leave this at the end of the file since section reader does not advance the reader
size, err := f.Seek(0, os.SEEK_END)
if err != nil {
return nil, errors.Wrap(err, "error getting current file size")
}
return io.NewSectionReader(f, 0, size), nil
}
// ReadLogs decodes entries from log files and sends them the passed in watcher
//
// Note: Using the follow option can become inconsistent in cases with very frequent rotations and max log files is 1.
// TODO: Consider a different implementation which can effectively follow logs under frequent rotations.
func (w *LogFile) ReadLogs(config ReadConfig, watcher *LogWatcher) {
w.mu.RLock()
currentFile, err := os.Open(w.f.Name())
if err != nil {
w.mu.RUnlock()
watcher.Err <- err
return
}
defer currentFile.Close()
currentChunk, err := newSectionReader(currentFile)
if err != nil {
w.mu.RUnlock()
watcher.Err <- err
return
}
if config.Tail != 0 {
// TODO(@cpuguy83): Instead of opening every file, only get the files which
// are needed to tail.
// This is especially costly when compression is enabled.
files, err := w.openRotatedFiles(config)
w.mu.RUnlock()
if err != nil {
watcher.Err <- err
return
}
closeFiles := func() {
for _, f := range files {
f.Close()
fileName := f.Name()
if strings.HasSuffix(fileName, tmpLogfileSuffix) {
err := w.filesRefCounter.Dereference(fileName)
if err != nil {
logrus.Errorf("Failed to dereference the log file %q: %v", fileName, err)
}
}
}
}
readers := make([]SizeReaderAt, 0, len(files)+1)
for _, f := range files {
stat, err := f.Stat()
if err != nil {
watcher.Err <- errors.Wrap(err, "error reading size of rotated file")
closeFiles()
return
}
readers = append(readers, io.NewSectionReader(f, 0, stat.Size()))
}
if currentChunk.Size() > 0 {
readers = append(readers, currentChunk)
}
tailFiles(readers, watcher, w.createDecoder, w.getTailReader, config)
closeFiles()
w.mu.RLock()
}
if !config.Follow || w.closed {
w.mu.RUnlock()
return
}
w.mu.RUnlock()
followLogs(currentFile, watcher, w.createDecoder, config.Since, config.Until)
}
func tailFiles(files []SizeReaderAt, watcher *LogWatcher, createDecoder makeDecoderFunc, getTailReader GetTailReaderFunc, config ReadConfig) {
nLines := config.Tail
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// TODO(@cpuguy83): we should plumb a context through instead of dealing with `WatchClose()` here.
go func() {
select {
case <-ctx.Done():
case <-watcher.WatchConsumerGone():
cancel()
}
}()
readers := make([]io.Reader, 0, len(files))
if config.Tail > 0 {
for i := len(files) - 1; i >= 0 && nLines > 0; i-- {
tail, n, err := getTailReader(ctx, files[i], nLines)
if err != nil {
watcher.Err <- errors.Wrap(err, "error finding file position to start log tailing")
return
}
nLines -= n
readers = append([]io.Reader{tail}, readers...)
}
} else {
for _, r := range files {
readers = append(readers, &wrappedReaderAt{ReaderAt: r})
}
}
rdr := io.MultiReader(readers...)
decodeLogLine := createDecoder(rdr)
for {
msg, err := decodeLogLine()
if err != nil {
if errors.Cause(err) != io.EOF {
watcher.Err <- err
}
return
}
if !config.Since.IsZero() && msg.Timestamp.Before(config.Since) {
continue
}
if !config.Until.IsZero() && msg.Timestamp.After(config.Until) {
return
}
select {
case <-ctx.Done():
return
case watcher.Msg <- msg:
}
}
}
func (w *LogFile) openRotatedFiles(config ReadConfig) (files []*os.File, err error) {
w.rotateMu.Lock()
defer w.rotateMu.Unlock()
defer func() {
if err == nil {
return
}
for _, f := range files {
f.Close()
if strings.HasSuffix(f.Name(), tmpLogfileSuffix) {
err := os.Remove(f.Name())
if err != nil && !os.IsNotExist(err) {
logrus.Warnf("Failed to remove logfile: %v", err)
}
}
}
}()
for i := w.maxFiles; i > 1; i-- {
f, err := os.Open(fmt.Sprintf("%s.%d", w.f.Name(), i-1))
if err != nil {
if !os.IsNotExist(err) {
return nil, errors.Wrap(err, "error opening rotated log file")
}
fileName := fmt.Sprintf("%s.%d.gz", w.f.Name(), i-1)
decompressedFileName := fileName + tmpLogfileSuffix
tmpFile, err := w.filesRefCounter.GetReference(decompressedFileName, func(refFileName string, exists bool) (*os.File, error) {
if exists {
return os.Open(refFileName)
}
return decompressfile(fileName, refFileName, config.Since)
})
if err != nil {
if !os.IsNotExist(errors.Cause(err)) {
return nil, errors.Wrap(err, "error getting reference to decompressed log file")
}
continue
}
if tmpFile == nil {
// The log before `config.Since` does not need to read
break
}
files = append(files, tmpFile)
continue
}
files = append(files, f)
}
return files, nil
}
func decompressfile(fileName, destFileName string, since time.Time) (*os.File, error) {
cf, err := os.Open(fileName)
if err != nil {
return nil, errors.Wrap(err, "error opening file for decompression")
}
defer cf.Close()
rc, err := gzip.NewReader(cf)
if err != nil {
return nil, errors.Wrap(err, "error making gzip reader for compressed log file")
}
defer rc.Close()
// Extract the last log entry timestramp from the gzip header
extra := &rotateFileMetadata{}
err = json.Unmarshal(rc.Header.Extra, extra)
if err == nil && extra.LastTime.Before(since) {
return nil, nil
}
rs, err := os.OpenFile(destFileName, os.O_CREATE|os.O_RDWR, 0640)
if err != nil {
return nil, errors.Wrap(err, "error creating file for copying decompressed log stream")
}
_, err = pools.Copy(rs, rc)
if err != nil {
rs.Close()
rErr := os.Remove(rs.Name())
if rErr != nil && !os.IsNotExist(rErr) {
logrus.Errorf("Failed to remove logfile: %v", rErr)
}
return nil, errors.Wrap(err, "error while copying decompressed log stream to file")
}
return rs, nil
}
func followLogs(f *os.File, logWatcher *LogWatcher, createDecoder makeDecoderFunc, since, until time.Time) {
decodeLogLine := createDecoder(f)
name := f.Name()
fileWatcher, err := watchFile(name)
if err != nil {
logWatcher.Err <- err
return
}
defer func() {
f.Close()
fileWatcher.Close()
}()
var retries int
handleRotate := func() error {
f.Close()
fileWatcher.Remove(name)
// retry when the file doesn't exist
for retries := 0; retries <= 5; retries++ {
f, err = os.Open(name)
if err == nil || !os.IsNotExist(err) {
break
}
}
if err != nil {
return err
}
if err := fileWatcher.Add(name); err != nil {
return err
}
decodeLogLine = createDecoder(f)
return nil
}
errRetry := errors.New("retry")
errDone := errors.New("done")
waitRead := func() error {
select {
case e := <-fileWatcher.Events():
switch e.Op {
case fsnotify.Write:
decodeLogLine = createDecoder(f)
return nil
case fsnotify.Rename, fsnotify.Remove:
select {
case <-logWatcher.WatchProducerGone():
return errDone
case <-logWatcher.WatchConsumerGone():
return errDone
default:
}
if err := handleRotate(); err != nil {
return err
}
return nil
}
return errRetry
case err := <-fileWatcher.Errors():
logrus.Debugf("logger got error watching file: %v", err)
// Something happened, let's try and stay alive and create a new watcher
if retries <= 5 {
fileWatcher.Close()
fileWatcher, err = watchFile(name)
if err != nil {
return err
}
retries++
return errRetry
}
return err
case <-logWatcher.WatchProducerGone():
return errDone
case <-logWatcher.WatchConsumerGone():
return errDone
}
}
handleDecodeErr := func(err error) error {
if errors.Cause(err) != io.EOF {
return err
}
for {
err := waitRead()
if err == nil {
break
}
if err == errRetry {
continue
}
return err
}
return nil
}
// main loop
for {
msg, err := decodeLogLine()
if err != nil {
if err := handleDecodeErr(err); err != nil {
if err == errDone {
return
}
// we got an unrecoverable error, so return
logWatcher.Err <- err
return
}
// ready to try again
continue
}
retries = 0 // reset retries since we've succeeded
if !since.IsZero() && msg.Timestamp.Before(since) {
continue
}
if !until.IsZero() && msg.Timestamp.After(until) {
return
}
// send the message, unless the consumer is gone
select {
case logWatcher.Msg <- msg:
case <-logWatcher.WatchConsumerGone():
return
}
}
}
func watchFile(name string) (filenotify.FileWatcher, error) {
var fileWatcher filenotify.FileWatcher
if runtime.GOOS == "windows" {
// FileWatcher on Windows files is based on the syscall notifications which has an issue because of file caching.
// It is based on ReadDirectoryChangesW() which doesn't detect writes to the cache. It detects writes to disk only.
// Because of the OS lazy writing, we don't get notifications for file writes and thereby the watcher
// doesn't work. Hence for Windows we will use poll based notifier.
fileWatcher = filenotify.NewPollingWatcher()
} else {
var err error
fileWatcher, err = filenotify.New()
if err != nil {
return nil, err
}
}
logger := logrus.WithFields(logrus.Fields{
"module": "logger",
"file": name,
})
if err := fileWatcher.Add(name); err != nil {
// we will retry using file poller.
logger.WithError(err).Warnf("falling back to file poller")
fileWatcher.Close()
fileWatcher = filenotify.NewPollingWatcher()
if err := fileWatcher.Add(name); err != nil {
fileWatcher.Close()
logger.WithError(err).Debugf("error watching log file for modifications")
return nil, err
}
}
return fileWatcher, nil
}
// LogFile is Logger implementation for default Docker logging.
type LogFile struct {
mu sync.RWMutex // protects the logfile access
f *os.File // store for closing
closed bool
rotateMu sync.Mutex // blocks the next rotation until the current rotation is completed
capacity int64 // maximum size of each file
currentSize int64 // current size of the latest file
maxFiles int // maximum number of files
compress bool // whether old versions of log files are compressed
lastTimestamp time.Time // timestamp of the last log
filesRefCounter refCounter // keep reference-counted of decompressed files
notifyRotate *pubsub.Publisher
createDecoder makeDecoderFunc
getTailReader GetTailReaderFunc
perms os.FileMode
}
//Close file close
func (w *LogFile) Close() error {
w.mu.Lock()
defer w.mu.Unlock()
if w.closed {
return nil
}
if err := w.f.Close(); err != nil {
return err
}
w.closed = true
return nil
}
//ReadConfig read log config
type ReadConfig struct {
Since time.Time
Until time.Time
Tail int
Follow bool
}
// SizeReaderAt defines a ReaderAt that also reports its size.
// This is used for tailing log files.
type SizeReaderAt interface {
io.ReaderAt
Size() int64
}
// NewLogFile creates new LogFile
func NewLogFile(logPath string, maxFiles int, compress bool, decodeFunc makeDecoderFunc, perms os.FileMode, getTailReader GetTailReaderFunc) (*LogFile, error) {
log, err := os.OpenFile(logPath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, perms)
if err != nil {
return nil, err
}
size, err := log.Seek(0, os.SEEK_END)
if err != nil {
return nil, err
}
return &LogFile{
f: log,
currentSize: size,
maxFiles: maxFiles,
compress: compress,
filesRefCounter: refCounter{counter: make(map[string]int)},
notifyRotate: pubsub.NewPublisher(0, 1),
createDecoder: decodeFunc,
perms: perms,
getTailReader: getTailReader,
}, nil
}
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