package daemon import ( "bytes" "encoding/json" "fmt" "io" "os" "strconv" "sync" "github.com/Sirupsen/logrus" "github.com/docker/docker/pkg/jsonlog" "github.com/docker/docker/pkg/stdcopy" "github.com/docker/docker/pkg/tailfile" "github.com/docker/docker/pkg/timeutils" ) type ContainerLogsConfig struct { Follow, Timestamps bool Tail string UseStdout, UseStderr bool OutStream io.Writer } func (daemon *Daemon) ContainerLogs(name string, config *ContainerLogsConfig) error { var ( lines = -1 format string ) if !(config.UseStdout || config.UseStderr) { return fmt.Errorf("You must choose at least one stream") } if config.Timestamps { format = timeutils.RFC3339NanoFixed } if config.Tail == "" { config.Tail = "all" } container, err := daemon.Get(name) if err != nil { return err } var ( outStream = config.OutStream errStream io.Writer ) if !container.Config.Tty { errStream = stdcopy.NewStdWriter(outStream, stdcopy.Stderr) outStream = stdcopy.NewStdWriter(outStream, stdcopy.Stdout) } else { errStream = outStream } if container.LogDriverType() != "json-file" { return fmt.Errorf("\"logs\" endpoint is supported only for \"json-file\" logging driver") } cLog, err := container.ReadLog("json") if err != nil && os.IsNotExist(err) { // Legacy logs logrus.Debugf("Old logs format") if config.UseStdout { cLog, err := container.ReadLog("stdout") if err != nil { logrus.Errorf("Error reading logs (stdout): %s", err) } else if _, err := io.Copy(outStream, cLog); err != nil { logrus.Errorf("Error streaming logs (stdout): %s", err) } } if config.UseStderr { cLog, err := container.ReadLog("stderr") if err != nil { logrus.Errorf("Error reading logs (stderr): %s", err) } else if _, err := io.Copy(errStream, cLog); err != nil { logrus.Errorf("Error streaming logs (stderr): %s", err) } } } else if err != nil { logrus.Errorf("Error reading logs (json): %s", err) } else { if config.Tail != "all" { var err error lines, err = strconv.Atoi(config.Tail) if err != nil { logrus.Errorf("Failed to parse tail %s, error: %v, show all logs", config.Tail, err) lines = -1 } } if lines != 0 { if lines > 0 { f := cLog.(*os.File) ls, err := tailfile.TailFile(f, lines) if err != nil { return err } tmp := bytes.NewBuffer([]byte{}) for _, l := range ls { fmt.Fprintf(tmp, "%s\n", l) } cLog = tmp } dec := json.NewDecoder(cLog) l := &jsonlog.JSONLog{} for { if err := dec.Decode(l); err == io.EOF { break } else if err != nil { logrus.Errorf("Error streaming logs: %s", err) break } logLine := l.Log if config.Timestamps { // format can be "" or time format, so here can't be error logLine, _ = l.Format(format) } if l.Stream == "stdout" && config.UseStdout { io.WriteString(outStream, logLine) } if l.Stream == "stderr" && config.UseStderr { io.WriteString(errStream, logLine) } l.Reset() } } } if config.Follow && container.IsRunning() { errors := make(chan error, 2) wg := sync.WaitGroup{} // write an empty chunk of data (this is to ensure that the // HTTP Response is sent immediatly, even if the container has // not yet produced any data) outStream.Write(nil) if config.UseStdout { wg.Add(1) stdoutPipe := container.StdoutLogPipe() defer stdoutPipe.Close() go func() { errors <- jsonlog.WriteLog(stdoutPipe, outStream, format) wg.Done() }() } if config.UseStderr { wg.Add(1) stderrPipe := container.StderrLogPipe() defer stderrPipe.Close() go func() { errors <- jsonlog.WriteLog(stderrPipe, errStream, format) wg.Done() }() } wg.Wait() close(errors) for err := range errors { if err != nil { logrus.Errorf("%s", err) } } } return nil }