From 73ceacd236480105b53325613209a01c6ebd78b7 Mon Sep 17 00:00:00 2001
From: Simon Zou <simon_zcs@hotmail.com>
Date: Thu, 6 Mar 2025 16:41:51 +0000
Subject: [PATCH] ListProcesses through PID when cgroup is not found in Linux
 (#25198)

* ListProcesses through PID when cgroup is not found

* add changelog entry

* update the ListByPid for windows
---
 .changelog/25198.txt                                | 3 +++
 drivers/shared/executor/executor_basic.go           | 2 +-
 drivers/shared/executor/executor_universal_linux.go | 8 +++++++-
 drivers/shared/executor/procstats/list_default.go   | 4 ++--
 drivers/shared/executor/procstats/list_windows.go   | 4 ++--
 5 files changed, 15 insertions(+), 6 deletions(-)
 create mode 100644 .changelog/25198.txt

diff --git a/.changelog/25198.txt b/.changelog/25198.txt
new file mode 100644
index 000000000..f57f2df2e
--- /dev/null
+++ b/.changelog/25198.txt
@@ -0,0 +1,3 @@
+```release-note:improvement
+metrics: Fix the process lookup for raw_exec when running rootless
+```
diff --git a/drivers/shared/executor/executor_basic.go b/drivers/shared/executor/executor_basic.go
index e96cdcff7..b22183cf4 100644
--- a/drivers/shared/executor/executor_basic.go
+++ b/drivers/shared/executor/executor_basic.go
@@ -38,7 +38,7 @@ func withNetworkIsolation(f func() error, _ *drivers.NetworkIsolationSpec) error
 func setCmdUser(*exec.Cmd, string) error { return nil }
 
 func (e *UniversalExecutor) ListProcesses() set.Collection[int] {
-	return procstats.List(e.childCmd.Process.Pid)
+	return procstats.ListByPid(e.childCmd.Process.Pid)
 }
 
 func (e *UniversalExecutor) setSubCmdCgroup(*exec.Cmd, string) (func(), error) {
diff --git a/drivers/shared/executor/executor_universal_linux.go b/drivers/shared/executor/executor_universal_linux.go
index b399b557e..53d042a6e 100644
--- a/drivers/shared/executor/executor_universal_linux.go
+++ b/drivers/shared/executor/executor_universal_linux.go
@@ -103,7 +103,13 @@ func (e *UniversalExecutor) setSubCmdCgroup(cmd *exec.Cmd, cgroup string) (func(
 }
 
 func (e *UniversalExecutor) ListProcesses() set.Collection[procstats.ProcessID] {
-	return procstats.List(e.command)
+	switch cgroupslib.GetMode() {
+	case cgroupslib.OFF:
+		// cgroup is unavailable, could possibly due to rootless nomad client
+		return procstats.ListByPid(e.childCmd.Process.Pid)
+	default:
+		return procstats.List(e.command)
+	}
 }
 
 func (e *UniversalExecutor) statCG(cgroup string) (int, func(), error) {
diff --git a/drivers/shared/executor/procstats/list_default.go b/drivers/shared/executor/procstats/list_default.go
index b6df7d386..0efd62bf0 100644
--- a/drivers/shared/executor/procstats/list_default.go
+++ b/drivers/shared/executor/procstats/list_default.go
@@ -1,7 +1,7 @@
 // Copyright (c) HashiCorp, Inc.
 // SPDX-License-Identifier: MPL-2.0
 
-//go:build !linux && !windows
+//go:build !windows
 
 package procstats
 
@@ -15,7 +15,7 @@ import (
 )
 
 // List the process tree starting at the given executorPID
-func List(executorPID int) set.Collection[ProcessID] {
+func ListByPid(executorPID int) set.Collection[ProcessID] {
 	result := set.New[ProcessID](10)
 
 	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
diff --git a/drivers/shared/executor/procstats/list_windows.go b/drivers/shared/executor/procstats/list_windows.go
index f32c8f257..721aabbc7 100644
--- a/drivers/shared/executor/procstats/list_windows.go
+++ b/drivers/shared/executor/procstats/list_windows.go
@@ -10,7 +10,7 @@ import (
 	"github.com/mitchellh/go-ps"
 )
 
-// List will scan the process table and return a set of the process family
+// ListByPid will scan the process table and return a set of the process family
 // tree starting with executorPID as the root.
 //
 // The implementation here specifically avoids using more than one system
@@ -25,7 +25,7 @@ import (
 // See https://github.com/hashicorp/nomad/issues/20042 as an example of what
 // happens when you use syscalls to work your way from the root down to its
 // descendants.
-func List(executorPID int) set.Collection[ProcessID] {
+func ListByPid(executorPID int) set.Collection[ProcessID] {
 	procs := list(executorPID, ps.Processes)
 	return procs
 }