Add logging feature for debug

This diff adds logging feature for debug.

vendor/github.com/vishvananda/netns/netns_linux.go

@@ -138,9 +138,7 @@ func getThisCgroup(cgroupType string) (string, error) {
 		return "", fmt.Errorf("docker pid not found in /var/run/docker.pid")
 	}
 	pid, err := strconv.Atoi(result[0])
-	if err != nil {
-		return "", err
-	}
+
 	output, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/cgroup", pid))
 	if err != nil {
 		return "", err
@@ -188,8 +186,6 @@ func getPidForContainer(id string) (int, error) {
 		filepath.Join(cgroupRoot, "system.slice", "docker-"+id+".scope", "tasks"),
 		// Even more recent docker versions under cgroup/systemd/docker/<id>/
 		filepath.Join(cgroupRoot, "..", "systemd", "docker", id, "tasks"),
-		// Kubernetes with docker and CNI is even more different
-		filepath.Join(cgroupRoot, "..", "systemd", "kubepods", "*", "pod*", id, "tasks"),
 	}
 
 	var filename string