Store cgroup manager on a per-container basis

When we create a container, we assign a cgroup parent based on
the current cgroup manager in use. This parent is only usable
with the cgroup manager the container is created with, so if the
default cgroup manager is later changed or overridden, the
container will not be able to start.

To solve this, store the cgroup manager that created the
container in container configuration, so we can guarantee a
container with a systemd cgroup parent will always be started
with systemd cgroups.

Unfortunately, this is very difficult to test in CI, due to the
fact that we hard-code cgroup manager on all invocations of
Podman in CI.

Fixes #7830

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

1 files changed, 3 insertions, 0 deletions

diff --git a/libpod/define/container_inspect.go b/libpod/define/container_inspect.go
index 44c3d515b..38b3a6686 100644
--- a/libpod/define/container_inspect.go
+++ b/libpod/define/container_inspect.go
@@ -236,6 +236,9 @@ type InspectContainerHostConfig struct {
 	// include a Mounts field in inspect.
 	// Format: <src>:<destination>[:<comma-separated options>]
 	Binds []string `json:"Binds"`
+	// CgroupManager is the cgroup manager used by the container.
+	// At present, allowed values are either "cgroupfs" or "systemd".
+	CgroupManager string `json:"CgroupManager,omitempty"`
 	// CgroupMode is the configuration of the container's cgroup namespace.
 	// Populated as follows:
 	// private - a cgroup namespace has been created