dbus: add GetUnitProcessesContext to list any unit's running processes

dbus/methods.go

@@ -862,3 +862,34 @@ func (c *Conn) FreezeUnit(ctx context.Context, unit string) error {
 func (c *Conn) ThawUnit(ctx context.Context, unit string) error {
 	return c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.ThawUnit", 0, unit).Store()
 }
+
+type Process struct {
+	Path    string // Where this process exists in the unit/cgroup hierarchy
+	PID     uint64 // The numeric process ID (PID)
+	Command string // The process command and arguments as a string
+}
+
+// GetUnitProcesses returns an array with all currently running processes in a unit *including* its child units.
+func (c *Conn) GetUnitProcesses(ctx context.Context, unit string) ([]Process, error) {
+	result := make([][]interface{}, 0)
+	if err := c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.GetUnitProcesses", 0, unit).Store(&result); err != nil {
+		return nil, err
+	}
+
+	resultInterface := make([]interface{}, len(result))
+	for i := range result {
+		resultInterface[i] = result[i]
+	}
+
+	process := make([]Process, len(result))
+	processInterface := make([]interface{}, len(process))
+	for i := range process {
+		processInterface[i] = &process[i]
+	}
+
+	if err := dbus.Store(resultInterface, processInterface...); err != nil {
+		return nil, err
+	}
+
+	return process, nil
+}

dbus/methods_test.go

@@ -22,6 +22,7 @@ import (
 	"path"
 	"path/filepath"
 	"reflect"
+	"strings"
 	"syscall"
 	"testing"
 	"time"
@@ -1689,3 +1690,45 @@ func TestFreezer(t *testing.T) {
 
 	runStopUnit(t, conn, TrUnitProp{target, nil})
 }
+
+func TestListUnitProcesses(t *testing.T) {
+	ctx := context.Background()
+	target := "list-me.service"
+
+	conn := setupConn(t)
+	defer conn.Close()
+
+	setupUnit(target, conn, t)
+	linkUnit(target, conn, t)
+
+	reschan := make(chan string)
+	_, err := conn.StartUnitContext(ctx, target, "replace", reschan)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer runStopUnit(t, conn, TrUnitProp{target, nil})
+
+	job := <-reschan
+	if job != "done" {
+		t.Fatal("Job is not done:", job)
+	}
+
+	processes, err := conn.GetUnitProcesses(ctx, target)
+
+	if err != nil {
+		e, ok := err.(dbus.Error)
+		if ok && (e.Name == "org.freedesktop.DBus.Error.UnknownMethod" || e.Name == "org.freedesktop.DBus.Error.NotSupported") {
+			t.SkipNow()
+		}
+		t.Fatalf("failed to list processes of %s: %s", target, err)
+	}
+
+	for _, p := range processes {
+		if strings.Contains(p.Command, "sleep") {
+			t.Logf("Found %v.\n", p)
+			return
+		}
+	}
+	t.Log("processes:", processes)
+	t.Error("The sleep process was not found in list-me.service unit's process list.")
+}

fixtures/list-me.service

@@ -0,0 +1,5 @@
+[Unit]
+Description=GetUnitProcesses test
+
+[Service]
+ExecStart=/bin/sleep 400