libpod: improve heuristic to detect cgroup

improve the heuristic to detect the scope that was created for the container.
This is necessary with systemd running as PID 1, since it moves itself
to a different sub-cgroup, thus stats would not account for other
processes in the same container.

Closes: https://github.com/containers/podman/issues/12400

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/libpod/container.go b/libpod/container.go
index c38acb513..482af43f3 100644
--- a/libpod/container.go
+++ b/libpod/container.go
@@ -6,9 +6,11 @@ import (
 	"io/ioutil"
 	"net"
 	"os"
+	"strings"
 	"time"
 
 	types040 "github.com/containernetworking/cni/pkg/types/040"
+	"github.com/containers/common/pkg/config"
 	"github.com/containers/common/pkg/secrets"
 	"github.com/containers/image/v5/manifest"
 	"github.com/containers/podman/v3/libpod/define"
@@ -963,6 +965,29 @@ func (c *Container) cGroupPath() (string, error) {
 		return "", errors.Errorf("could not find any cgroup in %q", procPath)
 	}
 
+	cgroupManager := c.CgroupManager()
+	switch {
+	case c.config.CgroupsMode == cgroupSplit:
+		name := fmt.Sprintf("/libpod-payload-%s/", c.ID())
+		if index := strings.LastIndex(cgroupPath, name); index >= 0 {
+			return cgroupPath[:index+len(name)-1], nil
+		}
+	case cgroupManager == config.CgroupfsCgroupsManager:
+		name := fmt.Sprintf("/libpod-%s/", c.ID())
+		if index := strings.LastIndex(cgroupPath, name); index >= 0 {
+			return cgroupPath[:index+len(name)-1], nil
+		}
+	case cgroupManager == config.SystemdCgroupsManager:
+		// When running under systemd, try to detect the scope that was requested
+		// to be created.  It improves the heuristic since we report the first
+		// cgroup that was created instead of the cgroup where PID 1 might have
+		// moved to.
+		name := fmt.Sprintf("/libpod-%s.scope/", c.ID())
+		if index := strings.LastIndex(cgroupPath, name); index >= 0 {
+			return cgroupPath[:index+len(name)-1], nil
+		}
+	}
+
 	return cgroupPath, nil
 }