Bugfix/procstat adds new procstat metric about pgrep search

internal/internal.go

@@ -11,6 +11,7 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 	"unicode"
 )
@@ -193,3 +194,15 @@ func RandomSleep(max time.Duration, shutdown chan struct{}) {
 		return
 	}
 }
+
+// Exit status takes the error from exec.Command
+// and returns the exit status and true
+// if error is not exit status, will return 0 and false
+func ExitStatus(err error) (int, bool) {
+	if exiterr, ok := err.(*exec.ExitError); ok {
+		if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
+			return status.ExitStatus(), true
+		}
+	}
+	return 0, false
+}

plugins/inputs/procstat/pgrep.go

@@ -6,6 +6,8 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+
+	"github.com/influxdata/telegraf/internal"
 )
 
 // Implemention of PIDGatherer that execs pgrep to find processes
@@ -62,8 +64,15 @@ func find(path string, args []string) ([]PID, error) {
 
 func run(path string, args []string) (string, error) {
 	out, err := exec.Command(path, args...).Output()
+
+	//if exit code 1, no processes found
+	if i, _ := internal.ExitStatus(err); i == 1 {
+		return "", nil
+	}
+
 	if err != nil {
-		return "", fmt.Errorf("Error running %s: %s", path, err)
+		//return "", fmt.Errorf("Error running %s: %s", path, err)
+		return "", fmt.Errorf("Error executing command: %v %v, err: %s", path, args, err)
 	}
 	return string(out), err
 }

plugins/inputs/procstat/procstat.go

@@ -104,6 +104,29 @@ func (p *Procstat) Gather(acc telegraf.Accumulator) error {
 	}
 	p.procs = procs
 
+	//adds a metric with info on the pgrep query
+	fields := make(map[string]interface{})
+	tags := make(map[string]string)
+	fields["pid_count"] = len(procs)
+	tags["pid_finder"] = p.PidFinder
+
+	//specific tags based on config
+	if p.PidFile != "" {
+		tags["pidfile"] = p.PidFile
+	} else if p.Exe != "" {
+		tags["exe"] = p.Exe
+	} else if p.Pattern != "" {
+		tags["pattern"] = p.Pattern
+	} else if p.User != "" {
+		tags["user"] = p.User
+	} else if p.SystemdUnit != "" {
+		tags["systemd_unit"] = p.SystemdUnit
+	} else if p.CGroup != "" {
+		tags["cgroup"] = p.CGroup
+	}
+
+	acc.AddFields("procstat_lookup", fields, tags)
+
 	for _, proc := range p.procs {
 		p.addMetrics(proc, acc)
 	}

plugins/inputs/procstat/procstat_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/testutil"
 	"github.com/shirou/gopsutil/cpu"
 	"github.com/shirou/gopsutil/process"
@@ -369,3 +370,39 @@ func TestGather_cgroupPIDs(t *testing.T) {
 	assert.Equal(t, []PID{1234, 5678}, pids)
 	assert.Equal(t, td, tags["cgroup"])
 }
+
+func TestExitStatus(t *testing.T) {
+	out, err := exec.Command("pgrep", "-G", "sys").Output()
+	t.Logf("cmd out: %v", out)
+	exitNum, _ := internal.ExitStatus(err)
+	t.Logf("error status: %v", exitNum)
+	require.Equal(t, 1, exitNum)
+}
+
+func TestNoPgrepResults(t *testing.T) {
+	p := Procstat{
+		PidFinder: "pgrep",
+		//executing this command should result exit status 1
+		Exe: "-Gsys",
+	}
+
+	var acc testutil.Accumulator
+	err := acc.GatherError(p.Gather)
+
+	t.Logf("gather err: %v", err)
+	require.NoError(t, err)
+}
+
+func TestProcstatMetrics(t *testing.T) {
+	p := Procstat{
+		PidFinder: "pgrep",
+		//executing this command should result exit status 1
+		Exe: "-Gsys",
+	}
+	var acc testutil.Accumulator
+	err := acc.GatherError(p.Gather)
+	require.NoError(t, err)
+	t.Logf("num of pids: %v", len(p.procs))
+	t.Logf("num of metrics: %v", len(acc.Metrics))
+	require.Equal(t, len(p.procs)+1, len(acc.Metrics))
+}