注：安装kubelet完成后，kubelet是不启动的，不能直接systemctl start kubelet，加入节点或初始化为master后即可启动成功~~~
查看kubelet状态
systemctl status kubelet
若k8s中的kubelet无法启动，在ubuntu系统中的启动配置文件/etc/systemd/system/kubelet.service.d/10-kubeadm.conf的内容应该如下：
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=cgroupfs"
Environment="KUBELET_SYSTEM_PODS_ARGS=--pod-manifest-path=/etc/kubernetes/manifests --allow-privileged=true --fail-swap-on=false"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/default/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS $KUBELET_CGROUP_ARGS $KUBELET_SWAP_ARGS $KUBELET_SYSTEM_PODS_ARGS
重启kubelet
systemctl daemon-reload
systemctl restart kubelet