79 lines
2.0 KiB
Go
79 lines
2.0 KiB
Go
package main
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import (
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"context"
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"io"
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"log"
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"github.com/alecthomas/kingpin"
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"github.com/nxadm/tail"
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)
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// A FileLogSource can read lines from a file.
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type FileLogSource struct {
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tailer *tail.Tail
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}
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// NewFileLogSource creates a new log source, tailing the given file.
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func NewFileLogSource(path string) (*FileLogSource, error) {
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tailer, err := tail.TailFile(path, tail.Config{
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ReOpen: true, // reopen the file if it's rotated
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MustExist: true, // fail immediately if the file is missing or has incorrect permissions
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Follow: true, // run in follow mode
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Location: &tail.SeekInfo{Whence: io.SeekEnd}, // seek to end of file
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Logger: tail.DiscardingLogger,
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})
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if err != nil {
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return nil, err
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}
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return &FileLogSource{tailer}, nil
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}
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func (s *FileLogSource) Close() error {
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defer s.tailer.Cleanup()
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go func() {
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// Stop() waits for the tailer goroutine to shut down, but it
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// can be blocking on sending on the Lines channel...
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for range s.tailer.Lines {
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}
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}()
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return s.tailer.Stop()
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}
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func (s *FileLogSource) Path() string {
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return s.tailer.Filename
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}
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func (s *FileLogSource) Read(ctx context.Context) (string, error) {
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select {
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case line, ok := <-s.tailer.Lines:
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if !ok {
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return "", io.EOF
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}
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return line.Text, nil
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case <-ctx.Done():
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return "", ctx.Err()
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}
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}
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// A fileLogSourceFactory is a factory than can create log sources
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// from command line flags.
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//
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// Because this factory is enabled by default, it must always be
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// registered last.
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type fileLogSourceFactory struct {
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path string
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}
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func (f *fileLogSourceFactory) Init(app *kingpin.Application) {
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app.Flag("postfix.logfile_path", "Path where Postfix writes log entries.").Default("/var/log/mail.log").StringVar(&f.path)
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}
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func (f *fileLogSourceFactory) New(ctx context.Context) (LogSourceCloser, error) {
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if f.path == "" {
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return nil, nil
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}
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log.Printf("Reading log events from %s", f.path)
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return NewFileLogSource(f.path)
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}
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