k8s限制节点启动pod数量（kubeadm部署）

参考：http://dockone.io/article/2434542

https://developer.aliyun.com/article/760653

Node节点默认的Pod数量

Kubernetes Node节点每个默认允许最多创建110个Pod，有时可能会由于系统硬件的问题，从而需要控制Node节点的Pod的运行数量。
即：需要调整Node节点的最大可运行Pod数量。
一般来说，我们只需要在kubelet启动命令中增加–max-pods参数，然后，重启kubelet 服务，就生效。

重启kubelet，不影响现有运行中的容器，不会造成容器重启。

修改限制Pod启动数量

 可以看到，集群当前有3台Node节点，且最大可运行Pod数量均为默认值：110。

1、登录 Node 节点，查看kubelet启动文件路径

[root@k8s01-zongshuai kube]# systemctl status kubelet

 修改文件/usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf

添加： Environment="KUBELET_NODE_MAX_PODS=--max-pods=200"

$KUBELET_NODE_MAX_PODS

[root@k8s01-zongshuai kube]# cd /usr/lib/systemd/system/kubelet.service.d/
[root@k8s01-zongshuai kubelet.service.d]# vim 10-kubeadm.conf

[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_NODE_MAX_PODS=--max-pods=200"
# 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/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS $KUBELET_NODE_MAX_PODS

 2、重启kubelet

[root@k8s01-zongshuai kubelet.service.d]# systemctl daemon-reload
[root@k8s01-zongshuai kubelet.service.d]# systemctl restart kubelet

3、检查配置生效

[root@k8s01-zongshuai kubelet.service.d]# ps aux|grep kubelet