feat(inputs.procstat): Add child level tag (#16105)

Co-authored-by: Thomas Casteleyn <thomas.casteleyn@me.com>

plugins/inputs/procstat/README.md

@@ -77,6 +77,8 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   ##   dest      -- destination address of the process socket (non-unix sockets)
   ##   dest_port -- destination port of the process socket (non-unix sockets)
   ##   name      -- name of the process socket (unix sockets only)
+  ## Available for procstat_lookup:
+  ##   level     -- level of the process filtering
   # tag_with = []
 
   ## Properties to collect
@@ -176,6 +178,8 @@ Below are an example set of tags and fields:
     - cgroup_full (when cgroup or systemd_unit is used with glob)
     - supervisor_unit (when defined)
     - win_service (when defined)
+    - parent_pid (for child processes)
+    - child_level (for child processes)
   - fields:
     - child_major_faults (int)
     - child_minor_faults (int)

plugins/inputs/procstat/filter.go

@@ -202,9 +202,11 @@ func (f *filter) applyFilter() ([]processGroup, error) {
 					tags[k] = v
 				}
 				tags["parent_pid"] = strconv.FormatInt(int64(p.Pid), 10)
+
 				children = append(children, processGroup{
 					processes: c,
 					tags:      tags,
+					level:     depth + 1,
 				})
 			}
 		}

plugins/inputs/procstat/procstat.go

@@ -76,6 +76,7 @@ type pidsTags struct {
 type processGroup struct {
 	processes []*gopsprocess.Process
 	tags      map[string]string
+	level     int
 }
 
 func (*Procstat) SampleConfig() string {
@@ -98,7 +99,7 @@ func (p *Procstat) Init() error {
 	p.cfg.tagging = make(map[string]bool, len(p.TagWith))
 	for _, tag := range p.TagWith {
 		switch tag {
-		case "cmdline", "pid", "ppid", "status", "user":
+		case "cmdline", "pid", "ppid", "status", "user", "child_level", "parent_pid", "level":
 		case "protocol", "state", "src", "src_port", "dest", "dest_port", "name": // socket only
 			if !slices.Contains(p.Properties, "sockets") {
 				return fmt.Errorf("socket tagging option %q specified without sockets enabled", tag)
@@ -349,6 +350,7 @@ func (p *Procstat) gatherNew(acc telegraf.Accumulator) error {
 		var count int
 		for _, g := range groups {
 			count += len(g.processes)
+			level := strconv.Itoa(g.level)
 			for _, gp := range g.processes {
 				// Skip over non-running processes
 				if running, err := gp.IsRunning(); err != nil || !running {
@@ -375,6 +377,9 @@ func (p *Procstat) gatherNew(acc telegraf.Accumulator) error {
 						process.setTag("process_name", p.ProcessName)
 					}
 					tags["filter"] = f.Name
+					if p.cfg.tagging["level"] {
+						tags["level"] = level
+					}
 
 					process = &proc{
 						Process:     gp,
@@ -394,6 +399,23 @@ func (p *Procstat) gatherNew(acc telegraf.Accumulator) error {
 					acc.AddMetric(m)
 				}
 			}
+			if p.cfg.tagging["level"] {
+				// Add lookup statistics-metric
+				acc.AddFields(
+					"procstat_lookup",
+					map[string]interface{}{
+						"pid_count":   len(g.processes),
+						"running":     len(running),
+						"result_code": 0,
+						"level":       g.level,
+					},
+					map[string]string{
+						"filter": f.Name,
+						"result": "success",
+					},
+					now,
+				)
+			}
 		}
 
 		// Add lookup statistics-metric

plugins/inputs/procstat/sample.conf

@@ -48,6 +48,8 @@
   ##   dest      -- destination address of the process socket (non-unix sockets)
   ##   dest_port -- destination port of the process socket (non-unix sockets)
   ##   name      -- name of the process socket (unix sockets only)
+  ## Available for procstat_lookup:
+  ##   level     -- level of the process filtering
   # tag_with = []
 
   ## Properties to collect