Ensure that rootless cgroupsv1 will select cgroupfs

The current logic is that, if Podman was built with the systemd
build flag, we will always select systemd cgroups by default.
Then, if we detect no systemd dbus session, we will swap to
cgroupfs. Problem: there are cases where a systemd dbus session
is available, but systemd cgroups don't work - most notably,
rootless mode on cgroups v1 systems. Special-case this so that we
will not try to force systemd mode and break rootless containers.

Fixes containers/podman#6982

Signed-off-by: Matthew Heon <[email protected]>

pkg/config/systemd.go

@@ -2,7 +2,17 @@
 
 package config
 
+import (
+	"github.com/containers/common/pkg/cgroupv2"
+	"github.com/containers/storage/pkg/unshare"
+)
+
 func defaultCgroupManager() string {
+	enabled, err := cgroupv2.Enabled()
+	if err == nil && !enabled && unshare.IsRootless() {
+		return CgroupfsCgroupsManager
+	}
+
 	return SystemdCgroupsManager
 }
 func defaultEventsLogger() string {