Add support for launching containers without CGroups

This is mostly used with Systemd, which really wants to manage
CGroups itself when managing containers via unit file.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 10 insertions, 1 deletions

diff --git a/libpod/oci_internal_linux.go b/libpod/oci_internal_linux.go
index 48b7370e0..f9e935d86 100644
--- a/libpod/oci_internal_linux.go
+++ b/libpod/oci_internal_linux.go
@@ -263,7 +263,7 @@ func (r *OCIRuntime) configureConmonEnv(runtimeDir string) ([]string, []*os.File
 func (r *OCIRuntime) sharedConmonArgs(ctr *Container, cuuid, bundlePath, pidPath, logPath, exitDir, ociLogPath string) []string {
 	// set the conmon API version to be able to use the correct sync struct keys
 	args := []string{"--api-version", "1"}
-	if r.cgroupManager == SystemdCgroupsManager {
+	if r.cgroupManager == SystemdCgroupsManager && !ctr.config.NoCgroups {
 		args = append(args, "-s")
 	}
 	args = append(args, "-c", ctr.ID())
@@ -307,6 +307,10 @@ func (r *OCIRuntime) sharedConmonArgs(ctr *Container, cuuid, bundlePath, pidPath
 	if ociLogPath != "" {
 		args = append(args, "--runtime-arg", "--log-format=json", "--runtime-arg", "--log", fmt.Sprintf("--runtime-arg=%s", ociLogPath))
 	}
+	if ctr.config.NoCgroups {
+		logrus.Debugf("Running with no CGroups")
+		args = append(args, "--runtime-arg", "--cgroup-manager", "--runtime-arg", "disabled")
+	}
 	return args
 }
 
@@ -355,6 +359,11 @@ func startCommandGivenSelinux(cmd *exec.Cmd) error {
 // moveConmonToCgroupAndSignal gets a container's cgroupParent and moves the conmon process to that cgroup
 // it then signals for conmon to start by sending nonse data down the start fd
 func (r *OCIRuntime) moveConmonToCgroupAndSignal(ctr *Container, cmd *exec.Cmd, startFd *os.File, uuid string) error {
+	// If cgroup creation is disabled - just signal.
+	if ctr.config.NoCgroups {
+		return writeConmonPipeData(startFd)
+	}
+
 	cgroupParent := ctr.CgroupParent()
 	if r.cgroupManager == SystemdCgroupsManager {
 		unitName := createUnitName("libpod-conmon", ctr.ID())