Make sandbox join the pod cgroup in K8s

cgroups in K8s are setup with the following hierarchy: `.../pod/container`.
The sandbox is created with the first container and consequently uses the
the pause container cgroup. This change removes the container cgroup from
the path to make the sandbox use the pod cgroup instead. Otherwise limits
set to the pause container will apply to the entire sandbox.

PiperOrigin-RevId: 374273277

1 files changed, 49 insertions, 1 deletions

diff --git a/pkg/shim/service.go b/pkg/shim/service.go
index 9d9fa8ef6..1f9adcb65 100644
--- a/pkg/shim/service.go
+++ b/pkg/shim/service.go
@@ -22,6 +22,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 	"sync"
 	"time"
 
@@ -44,6 +45,7 @@ import (
 	"github.com/containerd/containerd/sys/reaper"
 	"github.com/containerd/typeurl"
 	"github.com/gogo/protobuf/types"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/cleanup"
@@ -944,9 +946,19 @@ func newInit(path, workDir, namespace string, platform stdio.Platform, r *proc.C
 	if err != nil {
 		return nil, fmt.Errorf("read oci spec: %w", err)
 	}
-	if err := utils.UpdateVolumeAnnotations(r.Bundle, spec); err != nil {
+
+	updated, err := utils.UpdateVolumeAnnotations(spec)
+	if err != nil {
 		return nil, fmt.Errorf("update volume annotations: %w", err)
 	}
+	updated = updateCgroup(spec) || updated
+
+	if updated {
+		if err := utils.WriteSpec(r.Bundle, spec); err != nil {
+			return nil, err
+		}
+	}
+
 	runsc.FormatRunscLogPath(r.ID, options.RunscConfig)
 	runtime := proc.NewRunsc(options.Root, path, namespace, options.BinaryName, options.RunscConfig)
 	p := proc.New(r.ID, runtime, stdio.Stdio{
@@ -966,3 +978,39 @@ func newInit(path, workDir, namespace string, platform stdio.Platform, r *proc.C
 	p.Monitor = reaper.Default
 	return p, nil
 }
+
+// updateCgroup updates cgroup path for the sandbox to make the sandbox join the
+// pod cgroup and not the pause container cgroup. Returns true if the spec was
+// modified. Ex.:
+//   /kubepods/burstable/pod123/abc => kubepods/burstable/pod123
+//
+func updateCgroup(spec *specs.Spec) bool {
+	if !utils.IsSandbox(spec) {
+		return false
+	}
+	if spec.Linux == nil || len(spec.Linux.CgroupsPath) == 0 {
+		return false
+	}
+
+	// Search backwards for the pod cgroup path to make the sandbox use it,
+	// instead of the pause container's cgroup.
+	parts := strings.Split(spec.Linux.CgroupsPath, string(filepath.Separator))
+	for i := len(parts) - 1; i >= 0; i-- {
+		if strings.HasPrefix(parts[i], "pod") {
+			var path string
+			for j := 0; j <= i; j++ {
+				path = filepath.Join(path, parts[j])
+			}
+			// Add back the initial '/' that may have been lost above.
+			if filepath.IsAbs(spec.Linux.CgroupsPath) {
+				path = string(filepath.Separator) + path
+			}
+			if spec.Linux.CgroupsPath == path {
+				return false
+			}
+			spec.Linux.CgroupsPath = path
+			return true
+		}
+	}
+	return false
+}