package logger import ( "bufio" "bytes" "io" "sync" "time" "github.com/Sirupsen/logrus" ) // Copier can copy logs from specified sources to Logger and attach // ContainerID and Timestamp. // Writes are concurrent, so you need implement some sync in your logger type Copier struct { // cid is container id for which we copying logs cid string // srcs is map of name -> reader pairs, for example "stdout", "stderr" srcs map[string]io.Reader dst Logger copyJobs sync.WaitGroup } // NewCopier creates new Copier func NewCopier(cid string, srcs map[string]io.Reader, dst Logger) (*Copier, error) { return &Copier{ cid: cid, srcs: srcs, dst: dst, }, nil } // Run starts logs copying func (c *Copier) Run() { for src, w := range c.srcs { c.copyJobs.Add(1) go c.copySrc(src, w) } } func (c *Copier) copySrc(name string, src io.Reader) { defer c.copyJobs.Done() reader := bufio.NewReader(src) for { line, err := reader.ReadBytes('\n') line = bytes.TrimSuffix(line, []byte{'\n'}) // ReadBytes can return full or partial output even when it failed. // e.g. it can return a full entry and EOF. if err == nil || len(line) > 0 { if logErr := c.dst.Log(&Message{ContainerID: c.cid, Line: line, Source: name, Timestamp: time.Now().UTC()}); logErr != nil { logrus.Errorf("Failed to log msg %q for logger %s: %s", line, c.dst.Name(), logErr) } } if err != nil { if err != io.EOF { logrus.Errorf("Error scanning log stream: %s", err) } return } } } // Wait waits until all copying is done func (c *Copier) Wait() { c.copyJobs.Wait() }