kubelet failed with kubelet cgroup driver: "cgroupfs" is different from docker cgroup driver: "systemd"

Question

Configuration for cgroup driver is right in /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=systemd"

I also checked the Environment with cli

$ systemctl show --property=Environment kubelet | cat
Environment=KUBELET_KUBECONFIG_ARGS=--kubeconfig=/etc/kubernetes/kubelet.conf\x20--require-kubeconfig=true KUBELET_SYSTEM_PODS_ARGS=--pod-manifest-path=/etc/kubernetes/manifests\x20--allow-privileged=true KUBELET_NETWORK_ARGS=--network-plugin=cni\x20--cni-conf-dir=/etc/cni/net.d\x20--cni-bin-dir=/opt/cni/bin KUBELET_DNS_ARGS=--cluster-dns=10.96.0.10\x20--cluster-domain=cluster.local KUBELET_AUTHZ_ARGS=--authorization-mode=Webhook\x20--client-ca-file=/etc/kubernetes/pki/ca.crt KUBELET_CADVISOR_ARGS=--cadvisor-port=0 KUBELET_CGROUP_ARGS=--cgroup-driver=systemd

KUBELET_CGROUP_ARGS=--cgroup-driver=systemd

How to reproduce it:

• yum install -y docker-1.12.6
• systemctl enable docker && systemctl start docker
• setenforce 0
• yum install -y kubelet kubeadm
• systemctl enable kubelet && systemctl start kubelet
• systemctl daemon-reload
• systemctl restart kubelet
• kubelet log

Environment:

• Kubernetes version (use kubectl version): 1.7.3
• Cloud provider or hardware configuration**: 4 core 16G RAM
• OS (e.g. from /etc/os-release): CentOS Linux 7 (Core)
• Kernel (e.g. uname -a): Linux 10-8-108-92 3.10.0-327.22.2.el7.x86_64 #1 SMP Thu Jun 23 17:05:11 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
• Install tools: kubeadm

Answer 1

Possible cause

kubelet 1.7.3 not reading config file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf #50748

Solution

Troubleshooting kubeadm

If you are using CentOS and encounter difficulty while setting up the master node， verify that your Docker cgroup driver matches the kubelet config:

docker info | grep -i cgroup
cat /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

If the Docker cgroup driver and the kubelet config don’t match, change the kubelet config to match the Docker cgroup driver. The flag you need to change is --cgroup-driver. If it’s already set, you can update like so:

sed -i "s/cgroup-driver=systemd/cgroup-driver=cgroupfs/g /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

This can be replaced with:

CG=$(sudo docker info 2>/dev/null | sed -n 's/Cgroup Driver: \(.*\)/\1/p')
sed -i "s/cgroup-driver=systemd/cgroup-driver=$CG/g" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf