Improve ipvs input error strings and logging (influxdata#6530)

plugins/common/logrus/hook.go

@@ -0,0 +1,35 @@
+package logrus
+
+import (
+	"io/ioutil"
+	"log"
+	"strings"
+	"sync"
+
+	"github.com/sirupsen/logrus"
+)
+
+var once sync.Once
+
+type LogHook struct {
+}
+
+// Install a logging hook into the logrus standard logger, diverting all logs
+// through the Telegraf logger at debug level.  This is useful for libraries
+// that directly log to the logrus system without providing an override method.
+func InstallHook() {
+	once.Do(func() {
+		logrus.SetOutput(ioutil.Discard)
+		logrus.AddHook(&LogHook{})
+	})
+}
+
+func (h *LogHook) Fire(entry *logrus.Entry) error {
+	msg := strings.ReplaceAll(entry.Message, "\n", " ")
+	log.Print("D! [logrus] ", msg)
+	return nil
+}
+
+func (h *LogHook) Levels() []logrus.Level {
+	return logrus.AllLevels
+}

plugins/inputs/ipvs/ipvs.go

@@ -3,14 +3,14 @@
 package ipvs
 
 import (
-	"errors"
 	"fmt"
 	"math/bits"
 	"strconv"
 	"syscall"
 
 	"github.com/docker/libnetwork/ipvs"
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/common/logrus"
 	"github.com/influxdata/telegraf/plugins/inputs"
 )
 
@@ -35,7 +35,7 @@ func (i *IPVS) Gather(acc telegraf.Accumulator) error {
 	if i.handle == nil {
 		h, err := ipvs.New("") // TODO: make the namespace configurable
 		if err != nil {
-			return errors.New("Unable to open IPVS handle")
+			return fmt.Errorf("unable to open IPVS handle: %v", err)
 		}
 		i.handle = h
 	}
@@ -44,7 +44,7 @@ func (i *IPVS) Gather(acc telegraf.Accumulator) error {
 	if err != nil {
 		i.handle.Close()
 		i.handle = nil // trigger a reopen on next call to gather
-		return errors.New("Failed to list IPVS services")
+		return fmt.Errorf("failed to list IPVS services: %v", err)
 	}
 	for _, s := range services {
 		fields := map[string]interface{}{
@@ -61,7 +61,7 @@ func (i *IPVS) Gather(acc telegraf.Accumulator) error {
 
 		destinations, err := i.handle.GetDestinations(s)
 		if err != nil {
-			i.Log.Errorf("Failed to list destinations for a virtual server: %s", err.Error())
+			i.Log.Errorf("Failed to list destinations for a virtual server: %v", err)
 			continue // move on to the next virtual server
 		}
 
@@ -148,5 +148,8 @@ func addressFamilyToString(af uint16) string {
 }
 
 func init() {
-	inputs.Add("ipvs", func() telegraf.Input { return &IPVS{} })
+	inputs.Add("ipvs", func() telegraf.Input {
+		logrus.InstallHook()
+		return &IPVS{}
+	})
 }