kubeadm init: can't skip preflight checks if config is provided

[ericchiang]

Trying to run kubeadm from a container. Init fails because I'm not giving it access to iptables.

/ # kubeadm init --config config 
[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[init] Using Kubernetes version: v1.7.1
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks
[preflight] The system verification failed. Printing the output from the verification:
OS: Linux
KERNEL_VERSION: 4.10.16-100.fc24.x86_64
CGROUPS_CPU: enabled
CGROUPS_CPUACCT: enabled
CGROUPS_CPUSET: enabled
CGROUPS_DEVICES: enabled
CGROUPS_FREEZER: enabled
CGROUPS_MEMORY: enabled
[preflight] WARNING: no supported init system detected, skipping checking for services
[preflight] WARNING: no supported init system detected, skipping checking for services
[preflight] WARNING: no supported init system detected, skipping checking for services
[preflight] WARNING: ebtables not found in system path
[preflight] WARNING: ethtool not found in system path
[preflight] WARNING: socat not found in system path
[preflight] WARNING: tc not found in system path
[preflight] Some fatal errors occurred:
	failed to parse kernel config: unable to load kernel module "configs": output - "modprobe: can't change directory to '/lib/modules': No such file or directory\n", err - exit status 1
	failed to get docker info: Cannot connect to the Docker daemon. Is the docker daemon running on this host?
	/proc/sys/net/bridge/bridge-nf-call-iptables does not exist
	iptables not found in system path
[preflight] If you know what you are doing, you can skip pre-flight checks with `--skip-preflight-checks`

However, since I'm providing a config, I can't skip the checks

# kubeadm init --config config --skip-preflight-checks
[kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
[init] Using Kubernetes version: v1.7.1
[init] Using Authorization modes: [Node RBAC]
[preflight] Skipping pre-flight checks
can not mix '--config' with other arguments

There's also no config parameter to skip the check.