Add process created_at time to procstat input (#7039)

plugins/inputs/procstat/README.md

@@ -87,6 +87,7 @@ implemented as a WMI query.  The pattern allows fuzzy matching using only
   - fields:
     - child_major_faults (int)
     - child_minor_faults (int)
+    - created_at (int) [epoch in nanoseconds]
     - cpu_time (int)
     - cpu_time_guest (float)
     - cpu_time_guest_nice (float)
@@ -164,6 +165,6 @@ implemented as a WMI query.  The pattern allows fuzzy matching using only
 ### Example Output:
 
 ```
-procstat,pidfile=/var/run/lxc/dnsmasq.pid,process_name=dnsmasq rlimit_file_locks_soft=2147483647i,rlimit_signals_pending_hard=1758i,voluntary_context_switches=478i,read_bytes=307200i,cpu_time_user=0.01,cpu_time_guest=0,memory_swap=0i,memory_locked=0i,rlimit_num_fds_hard=4096i,rlimit_nice_priority_hard=0i,num_fds=11i,involuntary_context_switches=20i,read_count=23i,memory_rss=1388544i,rlimit_memory_rss_soft=2147483647i,rlimit_memory_rss_hard=2147483647i,nice_priority=20i,rlimit_cpu_time_hard=2147483647i,cpu_time=0i,write_bytes=0i,cpu_time_idle=0,cpu_time_nice=0,memory_data=229376i,memory_stack=135168i,rlimit_cpu_time_soft=2147483647i,rlimit_memory_data_hard=2147483647i,rlimit_memory_locked_hard=65536i,rlimit_signals_pending_soft=1758i,write_count=11i,cpu_time_iowait=0,cpu_time_steal=0,rlimit_memory_stack_soft=8388608i,cpu_time_system=0.02,cpu_time_guest_nice=0,rlimit_memory_locked_soft=65536i,rlimit_memory_vms_soft=2147483647i,rlimit_file_locks_hard=2147483647i,rlimit_realtime_priority_hard=0i,pid=828i,num_threads=1i,cpu_time_soft_irq=0,rlimit_memory_vms_hard=2147483647i,rlimit_realtime_priority_soft=0i,memory_vms=15884288i,rlimit_memory_stack_hard=2147483647i,cpu_time_irq=0,rlimit_memory_data_soft=2147483647i,rlimit_num_fds_soft=1024i,signals_pending=0i,rlimit_nice_priority_soft=0i,realtime_priority=0i
-procstat,exe=influxd,process_name=influxd rlimit_num_fds_hard=16384i,rlimit_signals_pending_hard=1758i,realtime_priority=0i,rlimit_memory_vms_hard=2147483647i,rlimit_signals_pending_soft=1758i,rlimit_memory_stack_hard=2147483647i,rlimit_realtime_priority_hard=0i,cpu_time=0i,pid=500i,voluntary_context_switches=975i,cpu_time_idle=0,memory_rss=3072000i,memory_locked=0i,rlimit_nice_priority_soft=0i,signals_pending=0i,nice_priority=20i,read_bytes=823296i,cpu_time_soft_irq=0,rlimit_memory_data_hard=2147483647i,rlimit_memory_locked_soft=65536i,write_count=8i,cpu_time_irq=0,memory_vms=33501184i,rlimit_memory_stack_soft=8388608i,cpu_time_iowait=0,rlimit_memory_vms_soft=2147483647i,rlimit_nice_priority_hard=0i,num_fds=29i,memory_data=229376i,rlimit_cpu_time_soft=2147483647i,rlimit_file_locks_soft=2147483647i,num_threads=1i,write_bytes=0i,cpu_time_steal=0,rlimit_memory_rss_hard=2147483647i,cpu_time_guest=0,cpu_time_guest_nice=0,cpu_usage=0,rlimit_memory_locked_hard=65536i,rlimit_file_locks_hard=2147483647i,involuntary_context_switches=38i,read_count=16851i,memory_swap=0i,rlimit_memory_data_soft=2147483647i,cpu_time_user=0.11,rlimit_cpu_time_hard=2147483647i,rlimit_num_fds_soft=16384i,rlimit_realtime_priority_soft=0i,cpu_time_system=0.27,cpu_time_nice=0,memory_stack=135168i,rlimit_memory_rss_soft=2147483647i
+procstat_lookup,host=prash-laptop,pattern=influxd,pid_finder=pgrep,result=success pid_count=1i,running=1i,result_code=0i 1582089700000000000
+procstat,host=prash-laptop,pattern=influxd,process_name=influxd,user=root involuntary_context_switches=151496i,child_minor_faults=1061i,child_major_faults=8i,cpu_time_user=2564.81,cpu_time_idle=0,cpu_time_irq=0,cpu_time_guest=0,pid=32025i,major_faults=8609i,created_at=1580107536000000000i,voluntary_context_switches=1058996i,cpu_time_system=616.98,cpu_time_steal=0,cpu_time_guest_nice=0,memory_swap=0i,memory_locked=0i,memory_usage=1.7797634601593018,num_threads=18i,cpu_time_nice=0,cpu_time_iowait=0,cpu_time_soft_irq=0,memory_rss=148643840i,memory_vms=1435688960i,memory_data=0i,memory_stack=0i,minor_faults=1856550i 1582089700000000000
 ```

plugins/inputs/procstat/process.go

@@ -25,6 +25,7 @@ type Process interface {
 	Times() (*cpu.TimesStat, error)
 	RlimitUsage(bool) ([]process.RlimitStat, error)
 	Username() (string, error)
+	CreateTime() (int64, error)
 }
 
 type PIDFinder interface {

plugins/inputs/procstat/procstat.go

@@ -216,6 +216,11 @@ func (p *Procstat) addMetric(proc Process, acc telegraf.Accumulator) {
 		fields[prefix+"write_bytes"] = io.WriteBytes
 	}
 
+	createdAt, err := proc.CreateTime() //Returns epoch in ms
+	if err == nil {
+		fields[prefix+"created_at"] = createdAt * 1000000 //Convert ms to ns
+	}
+
 	cpu_time, err := proc.Times()
 	if err == nil {
 		fields[prefix+"cpu_time_user"] = cpu_time.User

plugins/inputs/procstat/procstat_test.go

@@ -152,6 +152,10 @@ func (p *testProc) MemoryPercent() (float32, error) {
 	return 0, nil
 }
 
+func (p *testProc) CreateTime() (int64, error) {
+	return 0, nil
+}
+
 func (p *testProc) Times() (*cpu.TimesStat, error) {
 	return &cpu.TimesStat{}, nil
 }