Document and add support to input plugins for logging alias (#6357)

plugins/inputs/smart/smart.go

@@ -3,7 +3,6 @@ package smart
 import (
 	"bufio"
 	"fmt"
-	"log"
 	"os/exec"
 	"path"
 	"regexp"
@@ -120,6 +119,7 @@ type Smart struct {
 	Devices    []string
 	UseSudo    bool
 	Timeout    internal.Duration
+	Log        telegraf.Logger
 }
 
 var sampleConfig = `
@@ -209,10 +209,10 @@ func (m *Smart) scan() ([]string, error) {
 	for _, line := range strings.Split(string(out), "\n") {
 		dev := strings.Split(line, " ")
 		if len(dev) > 1 && !excludedDev(m.Excludes, strings.TrimSpace(dev[0])) {
-			log.Printf("D! [inputs.smart] adding device: %+#v", dev)
+			m.Log.Debugf("Adding device: %+#v", dev)
 			devices = append(devices, strings.TrimSpace(dev[0]))
 		} else {
-			log.Printf("D! [inputs.smart] skipping device: %+#v", dev)
+			m.Log.Debugf("Skipping device: %+#v", dev)
 		}
 	}
 	return devices, nil

plugins/inputs/smart/smart_test.go

@@ -15,6 +15,7 @@ import (
 
 func TestGatherAttributes(t *testing.T) {
 	s := NewSmart()
+	s.Log = testutil.Logger{}
 	s.Path = "smartctl"
 	s.Attributes = true
 
@@ -330,6 +331,7 @@ func TestGatherAttributes(t *testing.T) {
 
 func TestGatherNoAttributes(t *testing.T) {
 	s := NewSmart()
+	s.Log = testutil.Logger{}
 	s.Path = "smartctl"
 	s.Attributes = false