Add user tag to procstat input (influxdata#4386)

plugins/inputs/procstat/process.go

@@ -21,6 +21,7 @@ type Process interface {
 	Percent(interval time.Duration) (float64, error)
 	Times() (*cpu.TimesStat, error)
 	RlimitUsage(bool) ([]process.RlimitStat, error)
+	Username() (string, error)
 }
 
 type PIDFinder interface {
@@ -58,6 +59,10 @@ func (p *Proc) PID() PID {
 	return PID(p.Process.Pid)
 }
 
+func (p *Proc) Username() (string, error) {
+	return p.Process.Username()
+}
+
 func (p *Proc) Percent(interval time.Duration) (float64, error) {
 	cpu_perc, err := p.Process.Percent(time.Duration(0))
 	if !p.hasCPUTimes && err == nil {

plugins/inputs/procstat/procstat.go

@@ -128,6 +128,14 @@ func (p *Procstat) addMetrics(proc Process, acc telegraf.Accumulator) {
 		}
 	}
 
+	//If user tag is not already set, set to actual name
+	if _, ok := proc.Tags()["user"]; !ok {
+		user, err := proc.Username()
+		if err == nil {
+			proc.Tags()["user"] = user
+		}
+	}
+
 	//If pid is not present as a tag, include it as a field.
 	if _, pidInTags := proc.Tags()["pid"]; !pidInTags {
 		fields["pid"] = int32(proc.PID())

plugins/inputs/procstat/procstat_test.go

@@ -104,6 +104,10 @@ func (p *testProc) PID() PID {
 	return p.pid
 }
 
+func (p *testProc) Username() (string, error) {
+	return "testuser", nil
+}
+
 func (p *testProc) Tags() map[string]string {
 	return p.tags
 }