fix issue with execd-multiline influx line protocol (#7463)

plugins/inputs/execd/execd.go

@@ -15,6 +15,7 @@ import (
 	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/plugins/inputs"
 	"github.com/influxdata/telegraf/plugins/parsers"
+	"github.com/influxdata/telegraf/plugins/parsers/influx"
 )
 
 const sampleConfig = `
@@ -197,6 +198,12 @@ func (e *Execd) cmdWait() error {
 }
 
 func (e *Execd) cmdReadOut(out io.Reader) {
+	if _, isInfluxParser := e.parser.(*influx.Parser); isInfluxParser {
+		// work around the lack of built-in streaming parser. :(
+		e.cmdReadOutStream(out)
+		return
+	}
+
 	scanner := bufio.NewScanner(out)
 
 	for scanner.Scan() {
@@ -215,6 +222,29 @@ func (e *Execd) cmdReadOut(out io.Reader) {
 	}
 }
 
+func (e *Execd) cmdReadOutStream(out io.Reader) {
+	parser := influx.NewStreamParser(out)
+
+	for {
+		metric, err := parser.Next()
+		if err != nil {
+			if err == influx.EOF {
+				break // stream ended
+			}
+			if parseErr, isParseError := err.(*influx.ParseError); isParseError {
+				// parse error.
+				e.acc.AddError(parseErr)
+				continue
+			}
+			// some non-recoverable error?
+			e.acc.AddError(err)
+			return
+		}
+
+		e.acc.AddMetric(metric)
+	}
+}
+
 func (e *Execd) cmdReadErr(out io.Reader) {
 	scanner := bufio.NewScanner(out)
 

plugins/inputs/execd/execd_test.go

@@ -3,6 +3,8 @@
 package execd
 
 import (
+	"fmt"
+	"strings"
 	"testing"
 	"time"
 
@@ -47,6 +49,51 @@ func TestExternalInputWorks(t *testing.T) {
 	e.Gather(acc)
 }
 
+func TestParsesLinesContainingNewline(t *testing.T) {
+	parser, err := parsers.NewInfluxParser()
+	require.NoError(t, err)
+
+	metrics := make(chan telegraf.Metric, 10)
+	defer close(metrics)
+	acc := agent.NewAccumulator(&TestMetricMaker{}, metrics)
+
+	e := &Execd{
+		Command:      []string{shell(), fileShellScriptPath()},
+		RestartDelay: config.Duration(5 * time.Second),
+		parser:       parser,
+		Signal:       "STDIN",
+		acc:          acc,
+	}
+
+	cases := []struct {
+		Name  string
+		Value string
+	}{
+		{
+			Name:  "no-newline",
+			Value: "my message",
+		}, {
+			Name:  "newline",
+			Value: "my\nmessage",
+		},
+	}
+
+	for _, test := range cases {
+		t.Run(test.Name, func(t *testing.T) {
+			line := fmt.Sprintf("event message=\"%v\" 1587128639239000000", test.Value)
+
+			e.cmdReadOut(strings.NewReader(line))
+
+			m := readChanWithTimeout(t, metrics, 1*time.Second)
+
+			require.Equal(t, "event", m.Name())
+			val, ok := m.GetField("message")
+			require.True(t, ok)
+			require.Equal(t, test.Value, val)
+		})
+	}
+}
+
 func readChanWithTimeout(t *testing.T, metrics chan telegraf.Metric, timeout time.Duration) telegraf.Metric {
 	to := time.NewTimer(timeout)
 	defer to.Stop()