175 lines
4.1 KiB
Go
175 lines
4.1 KiB
Go
// Package jsonfilelog provides the default Logger implementation for
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// Docker logging. This logger logs to files on the host server in the
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// JSON format.
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package jsonfilelog
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"io"
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"strconv"
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"sync"
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"github.com/Sirupsen/logrus"
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"github.com/docker/docker/daemon/logger"
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"github.com/docker/docker/daemon/logger/loggerutils"
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"github.com/docker/docker/pkg/jsonlog"
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"github.com/docker/go-units"
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"github.com/pkg/errors"
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)
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// Name is the name of the file that the jsonlogger logs to.
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const Name = "json-file"
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// JSONFileLogger is Logger implementation for default Docker logging.
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type JSONFileLogger struct {
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extra []byte // json-encoded extra attributes
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mu sync.RWMutex
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buf *bytes.Buffer // avoids allocating a new buffer on each call to `Log()`
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closed bool
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writer *loggerutils.RotateFileWriter
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readers map[*logger.LogWatcher]struct{} // stores the active log followers
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}
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func init() {
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if err := logger.RegisterLogDriver(Name, New); err != nil {
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logrus.Fatal(err)
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}
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if err := logger.RegisterLogOptValidator(Name, ValidateLogOpt); err != nil {
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logrus.Fatal(err)
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}
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}
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// New creates new JSONFileLogger which writes to filename passed in
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// on given context.
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func New(info logger.Info) (logger.Logger, error) {
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var capval int64 = -1
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if capacity, ok := info.Config["max-size"]; ok {
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var err error
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capval, err = units.FromHumanSize(capacity)
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if err != nil {
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return nil, err
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}
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}
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var maxFiles = 1
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if maxFileString, ok := info.Config["max-file"]; ok {
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var err error
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maxFiles, err = strconv.Atoi(maxFileString)
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if err != nil {
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return nil, err
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}
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if maxFiles < 1 {
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return nil, fmt.Errorf("max-file cannot be less than 1")
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}
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}
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writer, err := loggerutils.NewRotateFileWriter(info.LogPath, capval, maxFiles)
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if err != nil {
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return nil, err
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}
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var extra []byte
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attrs, err := info.ExtraAttributes(nil)
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if err != nil {
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return nil, err
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}
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if len(attrs) > 0 {
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var err error
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extra, err = json.Marshal(attrs)
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if err != nil {
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return nil, err
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}
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}
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return &JSONFileLogger{
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buf: bytes.NewBuffer(nil),
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writer: writer,
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readers: make(map[*logger.LogWatcher]struct{}),
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extra: extra,
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}, nil
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}
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// Log converts logger.Message to jsonlog.JSONLog and serializes it to file.
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func (l *JSONFileLogger) Log(msg *logger.Message) error {
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l.mu.Lock()
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err := writeMessageBuf(l.writer, msg, l.extra, l.buf)
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l.buf.Reset()
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l.mu.Unlock()
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return err
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}
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func writeMessageBuf(w io.Writer, m *logger.Message, extra json.RawMessage, buf *bytes.Buffer) error {
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if err := marshalMessage(m, extra, buf); err != nil {
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logger.PutMessage(m)
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return err
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}
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logger.PutMessage(m)
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if _, err := w.Write(buf.Bytes()); err != nil {
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return errors.Wrap(err, "error writing log entry")
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}
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return nil
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}
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func marshalMessage(msg *logger.Message, extra json.RawMessage, buf *bytes.Buffer) error {
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timestamp, err := jsonlog.FastTimeMarshalJSON(msg.Timestamp)
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if err != nil {
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return err
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}
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logLine := msg.Line
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if !msg.Partial {
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logLine = append(msg.Line, '\n')
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}
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err = (&jsonlog.JSONLogs{
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Log: logLine,
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Stream: msg.Source,
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Created: timestamp,
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RawAttrs: extra,
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}).MarshalJSONBuf(buf)
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if err != nil {
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return errors.Wrap(err, "error writing log message to buffer")
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}
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err = buf.WriteByte('\n')
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return errors.Wrap(err, "error finalizing log buffer")
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}
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// ValidateLogOpt looks for json specific log options max-file & max-size.
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func ValidateLogOpt(cfg map[string]string) error {
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for key := range cfg {
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switch key {
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case "max-file":
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case "max-size":
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case "labels":
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case "env":
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case "env-regex":
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default:
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return fmt.Errorf("unknown log opt '%s' for json-file log driver", key)
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}
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}
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return nil
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}
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// LogPath returns the location the given json logger logs to.
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func (l *JSONFileLogger) LogPath() string {
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return l.writer.LogPath()
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}
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// Close closes underlying file and signals all readers to stop.
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func (l *JSONFileLogger) Close() error {
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l.mu.Lock()
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l.closed = true
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err := l.writer.Close()
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for r := range l.readers {
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r.Close()
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delete(l.readers, r)
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}
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l.mu.Unlock()
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return err
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}
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// Name returns name of this logger.
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func (l *JSONFileLogger) Name() string {
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return Name
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}
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