23023fa5ed
After tailing a file, if the number of lines requested is > the number of lines in the file, this would cause a json unmarshalling error to occur when we later try to go follow the file. So brute force set it to the end if any tailing occurred. There is potential that there could be some missing log messages if logs are being written very quickly, however I was not able to make this happen even with `while true; do echo hello; done`, so this is probably acceptable. While testing this I also found a panic in LogWatcher.Close can be called twice due to a race. Fix channel close to only close when there has been no signal to the channel. Signed-off-by: Brian Goff <cpuguy83@gmail.com> Upstream-commit: c57faa91e2dab72a0a0905dc10e5cbdf55b545f5 Component: engine
90 lines
2.4 KiB
Go
90 lines
2.4 KiB
Go
// Package logger defines interfaces that logger drivers implement to
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// log messages.
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//
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// The other half of a logger driver is the implementation of the
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// factory, which holds the contextual instance information that
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// allows multiple loggers of the same type to perform different
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// actions, such as logging to different locations.
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package logger
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import (
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"errors"
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"sync"
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"time"
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"github.com/docker/docker/pkg/timeutils"
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)
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// ErrReadLogsNotSupported is returned when the logger does not support reading logs.
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var ErrReadLogsNotSupported = errors.New("configured logging reader does not support reading")
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const (
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// TimeFormat is the time format used for timestamps sent to log readers.
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TimeFormat = timeutils.RFC3339NanoFixed
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logWatcherBufferSize = 4096
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)
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// Message is datastructure that represents record from some container.
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type Message struct {
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ContainerID string
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Line []byte
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Source string
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Timestamp time.Time
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}
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// Logger is the interface for docker logging drivers.
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type Logger interface {
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Log(*Message) error
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Name() string
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Close() error
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}
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// ReadConfig is the configuration passed into ReadLogs.
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type ReadConfig struct {
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Since time.Time
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Tail int
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Follow bool
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}
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// LogReader is the interface for reading log messages for loggers that support reading.
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type LogReader interface {
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// Read logs from underlying logging backend
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ReadLogs(ReadConfig) *LogWatcher
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}
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// LogWatcher is used when consuming logs read from the LogReader interface.
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type LogWatcher struct {
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// For sending log messages to a reader.
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Msg chan *Message
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// For sending error messages that occur while while reading logs.
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Err chan error
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closeNotifier chan struct{}
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closeOnce sync.Once
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}
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// NewLogWatcher returns a new LogWatcher.
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func NewLogWatcher() *LogWatcher {
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return &LogWatcher{
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Msg: make(chan *Message, logWatcherBufferSize),
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Err: make(chan error, 1),
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closeNotifier: make(chan struct{}),
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}
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}
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// Close notifies the underlying log reader to stop.
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func (w *LogWatcher) Close() {
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// only close if not already closed
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select {
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case <-w.closeNotifier:
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default:
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close(w.closeNotifier)
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}
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}
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// WatchClose returns a channel receiver that receives notification
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// when the watcher has been closed. This should only be called from
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// one goroutine.
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func (w *LogWatcher) WatchClose() <-chan struct{} {
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return w.closeNotifier
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}
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