fix cgroup detection during systemd service initialization

cgroup/cgroup.go

@@ -105,7 +105,10 @@ func NewFromProcessCgroupFile(filePath string) (*Cgroup, error) {
 			cg.subsystems[cgType] = path.Join(baseCgroupPath, parts[2])
 		}
 	}
-	if p := cg.subsystems["cpu"]; p != "" {
+	if p := cg.subsystems["name=systemd"]; p != "" {
+		cg.Id = p
+		cg.Version = V1
+	} else if p = cg.subsystems["cpu"]; p != "" {
 		cg.Id = p
 		cg.Version = V1
 	} else {

cgroup/cgroup_test.go

@@ -55,6 +55,13 @@ func TestNewFromProcessCgroupFile(t *testing.T) {
 	assert.Equal(t, "73051af271105c07e1f493b34856a77e665e3b0b4fc72f76c807dfbffeb881bd", cg.ContainerId)
 	assert.Equal(t, ContainerTypeDocker, cg.ContainerType)
 
+	cg, err = NewFromProcessCgroupFile(path.Join("fixtures/proc/600/cgroup"))
+	assert.Nil(t, err)
+	assert.Equal(t, V1, cg.Version)
+	assert.Equal(t, "/system.slice/springboot.service", cg.Id)
+	assert.Equal(t, "/system.slice/springboot.service", cg.ContainerId)
+	assert.Equal(t, ContainerTypeSystemdService, cg.ContainerType)
+
 	baseCgroupPath = "/kubepods.slice/kubepods-besteffort.slice/kubepods-besteffort-podc83d0428_58af_41eb_8dba_b9e6eddffe7b.slice/docker-0e612005fd07e7f47e2cd07df99a2b4e909446814d71d0b5e4efc7159dd51252.scope"
 	defer func() {
 		baseCgroupPath = ""

cgroup/fixtures/proc/600/cgroup

@@ -0,0 +1,11 @@
+11:freezer:/
+10:blkio:/init.scope
+9:hugetlb:/
+8:memory:/init.scope
+7:pids:/init.scope
+6:devices:/init.scope
+5:rdma:/
+4:cpuset:/
+3:net_cls,net_prio:/
+2:cpu,cpuacct:/
+1:name=systemd:/system.slice/springboot.service