Kubeadm: 지원되지 않는 그래프 드라이버 목록을 알 수 없음

@ggee 오류 메시지, docker 버전 정보, kubernetes 버전 정보 등을 제공해 주세요...

# kubeadm init
[kubeadm] WARNING: kubeadm is in alpha, please do not use it for production clusters.
[preflight] Running pre-flight checks
[preflight] The system verification failed. Printing the output from the verification:
OS: Linux
KERNEL_VERSION: 4.9.0-0.bpo.1-amd64
CONFIG_NAMESPACES: enabled
CONFIG_NET_NS: enabled
CONFIG_PID_NS: enabled
CONFIG_IPC_NS: enabled
CONFIG_UTS_NS: enabled
CONFIG_CGROUPS: enabled
CONFIG_CGROUP_CPUACCT: enabled
CONFIG_CGROUP_DEVICE: enabled
CONFIG_CGROUP_FREEZER: enabled
CONFIG_CGROUP_SCHED: enabled
CONFIG_CPUSETS: enabled
CONFIG_MEMCG: enabled
CONFIG_INET: enabled
CONFIG_EXT4_FS: enabled (as module)
CONFIG_PROC_FS: enabled
CONFIG_NETFILTER_XT_TARGET_REDIRECT: enabled (as module)
CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled (as module)
CONFIG_OVERLAY_FS: enabled (as module)
CONFIG_AUFS_FS: not set - Required for aufs.
CONFIG_BLK_DEV_DM: enabled (as module)
CGROUPS_CPU: enabled
CGROUPS_CPUACCT: enabled
CGROUPS_CPUSET: enabled
CGROUPS_DEVICES: enabled
CGROUPS_FREEZER: enabled
CGROUPS_MEMORY: enabled
DOCKER_VERSION: 1.13.1
DOCKER_GRAPH_DRIVER: overlay2
[preflight] Some fatal errors occurred:
    unsupported graph driver: overlay2
[preflight] If you know what you are doing, you can skip pre-flight checks with `--skip-preflight-checks`

# kubeadm version
kubeadm version: version.Info{Major:"1", Minor:"6+", GitVersion:"v1.6.0-alpha.0.2074+a092d8e0f95f52", GitCommit:"a092d8e0f95f5200f7ae2cba45c75ab42da36537", GitTreeState:"clean", BuildDate:"2016-12-13T17:03:18Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}

1.6.1, Ubuntu 16.04.2 x64와 동일합니다.

[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[preflight] Running pre-flight checks
[preflight] The system verification failed. Printing the output from the verification:
OS: Linux
KERNEL_VERSION: 4.4.0-62-generic
CONFIG_NAMESPACES: enabled
CONFIG_NET_NS: enabled
CONFIG_PID_NS: enabled
CONFIG_IPC_NS: enabled
CONFIG_UTS_NS: enabled
CONFIG_CGROUPS: enabled
CONFIG_CGROUP_CPUACCT: enabled
CONFIG_CGROUP_DEVICE: enabled
CONFIG_CGROUP_FREEZER: enabled
CONFIG_CGROUP_SCHED: enabled
CONFIG_CPUSETS: enabled
CONFIG_MEMCG: enabled
CONFIG_INET: enabled
CONFIG_EXT4_FS: enabled
CONFIG_PROC_FS: enabled
CONFIG_NETFILTER_XT_TARGET_REDIRECT: enabled (as module)
CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled (as module)
CONFIG_OVERLAY_FS: enabled (as module)
CONFIG_AUFS_FS: enabled (as module)
CONFIG_BLK_DEV_DM: enabled
CGROUPS_CPU: enabled
CGROUPS_CPUACCT: enabled
CGROUPS_CPUSET: enabled
CGROUPS_DEVICES: enabled
CGROUPS_FREEZER: enabled
CGROUPS_MEMORY: enabled
DOCKER_VERSION: 1.12.6
DOCKER_GRAPH_DRIVER: btrfs
[preflight] Some fatal errors occurred:
    unsupported graph driver: btrfs
[preflight] If you know what you are doing, you can skip pre-flight checks with `--skip-preflight-checks`

Docker는 실제로 btrfs를 사용합니다.

$ docker version
Client:
 Version:      1.12.6
 API version:  1.24
 Go version:   go1.6.4
 Git commit:   78d1802
 Built:        Tue Jan 10 20:38:45 2017
 OS/Arch:      linux/amd64

Server:
 Version:      1.12.6
 API version:  1.24
 Go version:   go1.6.4
 Git commit:   78d1802
 Built:        Tue Jan 10 20:38:45 2017
 OS/Arch:      linux/amd64
$ cat /etc/docker/daemon.json 
{
  "graph": "/data/docker",
  "storage-driver": "btrfs"
}

--skip-preflight-checks 로 노드는 마스터에 합류할 수 있었습니다.

이는 노드 팀이 공식적으로 오버레이2 드라이버의 유효성을 검사하지 않았기 때문이며 경고가 있는 그대로 작동합니다. 오버레이 2가 잘 작동해야한다고 생각하지만 ...