Tail input plugin

plugins/inputs/tail/tail.go

@@ -0,0 +1,152 @@
+package tail
+
+import (
+	"fmt"
+	"log"
+	"sync"
+
+	"github.com/hpcloud/tail"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal/globpath"
+	"github.com/influxdata/telegraf/plugins/inputs"
+	"github.com/influxdata/telegraf/plugins/parsers"
+)
+
+type Tail struct {
+	Files         []string
+	FromBeginning bool
+
+	tailers []*tail.Tail
+	parser  parsers.Parser
+	wg      sync.WaitGroup
+	acc     telegraf.Accumulator
+
+	sync.Mutex
+}
+
+const sampleConfig = `
+  ## files to tail.
+  ## These accept standard unix glob matching rules, but with the addition of
+  ## ** as a "super asterisk". ie:
+  ##   "/var/log/**.log"  -> recursively find all .log files in /var/log
+  ##   "/var/log/*/*.log" -> find all .log files with a parent dir in /var/log
+  ##   "/var/log/apache.log" -> just tail the apache log file
+  ##
+  ## See https://github.com/gobwas/glob for more examples
+  ##
+  files = ["/var/mymetrics.out"]
+  ## Read file from beginning.
+  from_beginning = false
+
+  ## Data format to consume.
+  ## Each data format has it's own unique set of configuration options, read
+  ## more about them here:
+  ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
+  data_format = "influx"
+`
+
+func (t *Tail) SampleConfig() string {
+	return sampleConfig
+}
+
+func (t *Tail) Description() string {
+	return "Stream a log file, like the tail -f command"
+}
+
+func (t *Tail) Gather(acc telegraf.Accumulator) error {
+	return nil
+}
+
+func (t *Tail) Start(acc telegraf.Accumulator) error {
+	t.Lock()
+	defer t.Unlock()
+
+	t.acc = acc
+
+	var seek tail.SeekInfo
+	if !t.FromBeginning {
+		seek.Whence = 2
+		seek.Offset = 0
+	}
+
+	var errS string
+	// Create a "tailer" for each file
+	for _, filepath := range t.Files {
+		g, err := globpath.Compile(filepath)
+		if err != nil {
+			log.Printf("ERROR Glob %s failed to compile, %s", filepath, err)
+		}
+		for file, _ := range g.Match() {
+			tailer, err := tail.TailFile(file,
+				tail.Config{
+					ReOpen:   true,
+					Follow:   true,
+					Location: &seek,
+				})
+			if err != nil {
+				errS += err.Error() + " "
+				continue
+			}
+			// create a goroutine for each "tailer"
+			go t.receiver(tailer)
+			t.tailers = append(t.tailers, tailer)
+		}
+	}
+
+	if errS != "" {
+		return fmt.Errorf(errS)
+	}
+	return nil
+}
+
+// this is launched as a goroutine to continuously watch a tailed logfile
+// for changes, parse any incoming msgs, and add to the accumulator.
+func (t *Tail) receiver(tailer *tail.Tail) {
+	t.wg.Add(1)
+	defer t.wg.Done()
+
+	var m telegraf.Metric
+	var err error
+	var line *tail.Line
+	for line = range tailer.Lines {
+		if line.Err != nil {
+			log.Printf("ERROR tailing file %s, Error: %s\n",
+				tailer.Filename, err)
+			continue
+		}
+		m, err = t.parser.ParseLine(line.Text)
+		if err == nil {
+			t.acc.AddFields(m.Name(), m.Fields(), m.Tags(), m.Time())
+		} else {
+			log.Printf("Malformed log line in %s: [%s], Error: %s\n",
+				tailer.Filename, line.Text, err)
+		}
+	}
+}
+
+func (t *Tail) Stop() {
+	t.Lock()
+	defer t.Unlock()
+
+	for _, t := range t.tailers {
+		err := t.Stop()
+		if err != nil {
+			log.Printf("ERROR stopping tail on file %s\n", t.Filename)
+		}
+		t.Cleanup()
+	}
+	t.wg.Wait()
+}
+
+func (t *Tail) SetParser(parser parsers.Parser) {
+	t.parser = parser
+}
+
+func init() {
+	inputs.Add("tail", func() telegraf.Input {
+		return &Tail{
+			FromBeginning: false,
+		}
+	})
+}