Update troubleshooting-kubeadm.md

Update troubleshooting docs about apiclient blocking while run `kubeadm init`.

docs/setup/independent/troubleshooting-kubeadm.md

@@ -34,13 +34,42 @@ If you see the following warnings while running `kubeadm init`
 
 Then you may be missing ebtables and ethtool on your Linux machine. You can install them with the following commands: 
 
-```
+- For ubuntu/debian users, try `apt install ebtables ethtool`.
-# For ubuntu/debian users, try 
+- For CentOS/Fedora users, try `yum install ebtables ethtool`.
-apt install ebtables ethtool
+
+#### kubeadm blocks waiting for `control plane` during installation
+
+If you see the following blocks while running `kubeadm init`
 
-# For CentOS/Fedora users, try 
-yum install ebtables ethtool
 ```
+[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
+[init] Using Kubernetes version: v1.8.0
+[init] Using Authorization modes: [Node RBAC]
+[preflight] Skipping pre-flight checks
+[kubeadm] WARNING: starting in 1.8, tokens expire after 24 hours by default (if you require a non-expiring token use --token-ttl 0)
+[certificates] Using the existing CA certificate and key.
+[certificates] Using the existing API Server certificate and key.
+[certificates] Using the existing API Server kubelet client certificate and key.
+[certificates] Using the existing service account token signing key.
+[certificates] Using the existing front-proxy CA certificate and key.
+[certificates] Using the existing front-proxy client certificate and key.
+[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
+[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/controller-manager.conf"
+[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/scheduler.conf"
+[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/admin.conf"
+[kubeconfig] Using existing up-to-date KubeConfig file: "/etc/kubernetes/kubelet.conf"
+[apiclient] Created API client, waiting for the control plane to become ready                          
+```
+
+Then there may can not connect to net or parameter `Cgroup Driver` diff bettween docker and kubelet in your linux machine. 
+
+- Ensure your machine can connect to net.
+- If you find some log in `var/log/message`, look like:
+```
+error: failed to run Kubelet: failed to create kubelet: 
+misconfiguration: kubelet cgroup driver: "systemd" is different from docker cgroup driver: "cgroupfs"
+```
+then modify startup parameter `KUBELET_CGROUP_ARGS=--cgroup-driver=` in `/etc/systemd/system/kubelet.service.d/10-kubeadm.conf`(Ubuntu).
 
 #### Pods in `RunContainerError`, `CrashLoopBackOff` or `Error` state