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: containers#12400 Signed-off-by: Giuseppe Scrivano <[email protected]>
giuseppe · Nov 24, 2021 · e648122 · e648122
1 parent a66f40b
commit e648122
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diff --git 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
 }
 

diff --git a/libpod/container_internal_linux.go b/libpod/container_internal_linux.go
@@ -2618,7 +2618,7 @@ func (c *Container) getOCICgroupPath() (string, error) {
 		if err != nil {
 			return "", err
 		}
-		return filepath.Join(selfCgroup, "container"), nil
+		return filepath.Join(selfCgroup, fmt.Sprintf("libpod-payload-%s", c.ID())), nil
 	case cgroupManager == config.SystemdCgroupsManager:
 		// When the OCI runtime is set to use Systemd as a cgroup manager, it
 		// expects cgroups to be passed as follows:

diff --git a/test/e2e/systemd_test.go b/test/e2e/systemd_test.go
@@ -109,6 +109,11 @@ WantedBy=multi-user.target
 		stats := podmanTest.Podman([]string{"stats", "--no-stream", ctrName})
 		stats.WaitWithDefaultTimeout()
 		Expect(stats).Should(Exit(0))
+
+		cgroupPath := podmanTest.Podman([]string{"inspect", "--format='{{.State.CgroupPath}}'", ctrName})
+		cgroupPath.WaitWithDefaultTimeout()
+		Expect(cgroupPath).Should(Exit(0))
+		Expect(result.OutputToString()).To(Not(ContainSubstring("init.scope")))
 	})
 
 	It("podman create container with systemd entrypoint triggers systemd mode", func() {