tests: add integration test for cgroups hybrid

Check that runc run and runc exec put the process on the same cgroups v2
when using hybrid mode.

Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/integration/cgroups.bats

@@ -282,3 +282,24 @@ function setup() {
 	[ "$status" -eq 0 ]
 	[ "$(wc -l <<<"$output")" -eq 1 ]
 }
+
+@test "runc exec (cgroup v1+hybrid joins correct cgroup)" {
+	requires root cgroups_hybrid
+
+	set_cgroups_path
+
+	runc run --pid-file pid.txt -d --console-socket "$CONSOLE_SOCKET" test_cgroups_group
+	[ "$status" -eq 0 ]
+
+	pid=$(cat pid.txt)
+	run_cgroup=$(tail -1 </proc/"$pid"/cgroup)
+	[[ "$run_cgroup" == *"runc-cgroups-integration-test"* ]]
+
+	runc exec test_cgroups_group cat /proc/self/cgroup
+	[ "$status" -eq 0 ]
+	exec_cgroup=${lines[-1]}
+	[[ $exec_cgroup == *"runc-cgroups-integration-test"* ]]
+
+	# check that the cgroups v2 path is the same for both processes
+	[[ "$run_cgroup" == "$exec_cgroup" ]]
+}

tests/integration/helpers.bash

@@ -127,6 +127,9 @@ function init_cgroup_paths() {
 			CGROUP_SUBSYSTEMS+=" freezer"
 		fi
 	else
+		if stat -f -c %t /sys/fs/cgroup/unified | grep -qFw 63677270; then
+			CGROUP_HYBRID=yes
+		fi
 		CGROUP_UNIFIED=no
 		CGROUP_SUBSYSTEMS=$(awk '!/^#/ {print $1}' /proc/cgroups)
 		local g base_path
@@ -410,6 +413,12 @@ function requires() {
 				skip_me=1
 			fi
 			;;
+		cgroups_hybrid)
+			init_cgroup_paths
+			if [ "$CGROUP_HYBRID" != "yes" ]; then
+				skip_me=1
+			fi
+			;;
 		cgroups_*)
 			init_cgroup_paths
 			var=${var#cgroups_}