feat(inputs.systemd_units): Support user scoped units (#15458)

plugins/inputs/systemd_units/README.md

@@ -31,6 +31,10 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   ## automount, swap, timer, path, slice and scope
   # unittype = "service"
 
+  ## Collect system or user scoped units
+  ##  ex: scope = "user"
+  # scope = "system"
+
   ## Collect also units not loaded by systemd, i.e. disabled or static units
   ## Enabling this feature might introduce significant load when used with
   ## unspecific patterns (such as '*') as systemd will need to load all
@@ -69,6 +73,7 @@ These metrics are available in both modes:
     - load (string, load state)
     - active (string, active state)
     - sub (string, sub state)
+    - user (string, username only for user scope)
   - fields:
     - load_code (int, see below)
     - active_code (int, see below)
@@ -198,15 +203,15 @@ were removed, tables are hex aligned to keep some space for future values
 ### Output in non-detailed mode
 
 ```text
-systemd_units,host=host1.example.com,name=dbus.service,load=loaded,active=active,sub=running load_code=0i,active_code=0i,sub_code=0i 1533730725000000000
+systemd_units,host=host1.example.com,name=dbus.service,load=loaded,active=active,sub=running,user=telegraf load_code=0i,active_code=0i,sub_code=0i 1533730725000000000
-systemd_units,host=host1.example.com,name=networking.service,load=loaded,active=failed,sub=failed load_code=0i,active_code=3i,sub_code=12i 1533730725000000000
+systemd_units,host=host1.example.com,name=networking.service,load=loaded,active=failed,sub=failed,user=telegraf load_code=0i,active_code=3i,sub_code=12i 1533730725000000000
-systemd_units,host=host1.example.com,name=ssh.service,load=loaded,active=active,sub=running load_code=0i,active_code=0i,sub_code=0i 1533730725000000000
+systemd_units,host=host1.example.com,name=ssh.service,load=loaded,active=active,sub=running,user=telegraf load_code=0i,active_code=0i,sub_code=0i 1533730725000000000
 ```
 
 ### Output in detailed mode
 
 ```text
-systemd_units,active=active,host=host1.example.com,load=loaded,name=dbus.service,sub=running,preset=disabled,state=static active_code=0i,load_code=0i,mem_avail=6470856704i,mem_current=2691072i,mem_peak=3895296i,pid=481i,restarts=0i,status_errno=0i,sub_code=0i,swap_current=794624i,swap_peak=884736i 1533730725000000000
+systemd_units,active=active,host=host1.example.com,load=loaded,name=dbus.service,sub=running,preset=disabled,state=static,user=telegraf active_code=0i,load_code=0i,mem_avail=6470856704i,mem_current=2691072i,mem_peak=3895296i,pid=481i,restarts=0i,status_errno=0i,sub_code=0i,swap_current=794624i,swap_peak=884736i 1533730725000000000
-systemd_units,active=inactive,host=host1.example.com,load=not-found,name=networking.service,sub=dead active_code=2i,load_code=2i,pid=0i,restarts=0i,status_errno=0i,sub_code=1i 1533730725000000000
+systemd_units,active=inactive,host=host1.example.com,load=not-found,name=networking.service,sub=dead,user=telegraf active_code=2i,load_code=2i,pid=0i,restarts=0i,status_errno=0i,sub_code=1i 1533730725000000000
-systemd_units,active=active,host=host1.example.com,load=loaded,name=pcscd.service,sub=running,preset=disabled,state=indirect active_code=0i,load_code=0i,mem_avail=6370541568i,mem_current=512000i,mem_peak=4399104i,pid=1673i,restarts=0i,status_errno=0i,sub_code=0i,swap_current=3149824i,swap_peak=3149824i 1533730725000000000
+systemd_units,active=active,host=host1.example.com,load=loaded,name=pcscd.service,sub=running,preset=disabled,state=indirect,user=telegraf active_code=0i,load_code=0i,mem_avail=6370541568i,mem_current=512000i,mem_peak=4399104i,pid=1673i,restarts=0i,status_errno=0i,sub_code=0i,swap_current=3149824i,swap_peak=3149824i 1533730725000000000
 ```

plugins/inputs/systemd_units/sample.conf

@@ -12,6 +12,10 @@
   ## automount, swap, timer, path, slice and scope
   # unittype = "service"
 
+  ## Collect system or user scoped units
+  ##  ex: scope = "user"
+  # scope = "system"
+
   ## Collect also units not loaded by systemd, i.e. disabled or static units
   ## Enabling this feature might introduce significant load when used with
   ## unspecific patterns (such as '*') as systemd will need to load all

plugins/inputs/systemd_units/systemd_units.go

@@ -17,6 +17,7 @@ var sampleConfig string
 type SystemdUnits struct {
 	Pattern         string          `toml:"pattern"`
 	UnitType        string          `toml:"unittype"`
+	Scope           string          `toml:"scope"`
 	Details         bool            `toml:"details"`
 	CollectDisabled bool            `toml:"collect_disabled_units"`
 	Timeout         config.Duration `toml:"timeout"`

plugins/inputs/systemd_units/systemd_units_linux.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"fmt"
 	"math"
+	"os/user"
 	"path"
 	"strings"
 	"time"
@@ -131,6 +132,8 @@ type archParams struct {
 	pattern      []string
 	filter       filter.Filter
 	unitTypeDBus string
+	scope        string
+	user         string
 }
 
 func (s *SystemdUnits) Init() error {
@@ -158,15 +161,38 @@ func (s *SystemdUnits) Init() error {
 	}
 	s.filter = f
 
+	switch s.Scope {
+	case "", "system":
+		s.scope = "system"
+	case "user":
+		u, err := user.Current()
+		if err != nil {
+			return fmt.Errorf("unable to determine user: %w", err)
+		}
+
+		s.scope = "user"
+		s.user = u.Username
+	default:
+		return fmt.Errorf("invalid 'scope' %q", s.Scope)
+	}
+
 	return nil
 }
 
 func (s *SystemdUnits) Start(telegraf.Accumulator) error {
 	ctx := context.Background()
-	client, err := dbus.NewSystemConnectionContext(ctx)
+
+	var client *dbus.Conn
+	var err error
+	if s.scope == "user" {
+		client, err = dbus.NewUserConnectionContext(ctx)
+	} else {
+		client, err = dbus.NewSystemConnectionContext(ctx)
+	}
 	if err != nil {
 		return err
 	}
+
 	s.client = client
 
 	return nil
@@ -321,6 +347,9 @@ func (s *SystemdUnits) Gather(acc telegraf.Accumulator) error {
 			"active": state.ActiveState,
 			"sub":    state.SubState,
 		}
+		if s.scope == "user" {
+			tags["user"] = s.user
+		}
 
 		fields := map[string]interface{}{
 			"load_code":   load,

plugins/inputs/systemd_units/systemd_units_test.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"os/user"
 	"strings"
 	"testing"
 	"time"
@@ -38,6 +39,50 @@ func TestDefaultPattern(t *testing.T) {
 	require.Equal(t, "*", plugin.Pattern)
 }
 
+func TestDefaultScope(t *testing.T) {
+	u, err := user.Current()
+	if err != nil {
+		return
+	}
+
+	tests := []struct {
+		name          string
+		scope         string
+		expectedScope string
+		expectedUser  string
+	}{
+		{
+			name:          "default scope",
+			scope:         "",
+			expectedScope: "system",
+			expectedUser:  "",
+		},
+		{
+			name:          "system scope",
+			scope:         "system",
+			expectedScope: "system",
+			expectedUser:  "",
+		},
+		{
+			name:          "user scope",
+			scope:         "user",
+			expectedScope: "user",
+			expectedUser:  u.Username,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			plugin := &SystemdUnits{
+				Scope: tt.scope,
+			}
+			require.NoError(t, plugin.Init())
+			require.Equal(t, tt.expectedScope, plugin.scope)
+			require.Equal(t, tt.expectedUser, plugin.user)
+		})
+	}
+}
+
 func TestListFiles(t *testing.T) {
 	tests := []struct {
 		name        string