Kubernetes 限制节点启动的 Pod 数量

一、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。

二、修改限制Pod启动数量

• 修改需要在个个节点上操作

root@k8s-master-0001:/etc/systemd/system/kubelet.service.d$ kubectl describe nodes k8s-node-0001 | grep pod
  pods:               110
  pods:               110
  Normal   NodeAllocatableEnforced  18s                 kubelet  Updated Node Allocatable limit across pods

2.1、修改配置

vim /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
# 添加参数
Environment="KUBELET_NODE_MAX_PODS=--max-pods=200"
# 增加环境变量 $KUBELET_EXTRA_ARGS
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS $KUBELET_NODE_MAX_PODS

2.2、修改后配置

root@k8s-node-0001:/$ cat /etc/systemd/system/kubelet.service.d/10-kubeadm.conf 
# 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_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

2.3、重启 Kubelet

systemctl daemon-reload
systemctl restart kubelet

2.4、查看结果

• 在 master 节点上查看结果

root@k8s-master-0001:/$ kubectl describe nodes k8s-node-0001 | grep pod
  pods:               200
  pods:               200
  Normal   NodeAllocatableEnforced  18s                 kubelet  Updated Node Allocatable limit across pods