Kubernetes （三）资源预留

一、kubernetes中的资源计算方式

节点可为pod分配的资源计算方法：

Node Allocatable Resource = Node Capacity（资源总大小） - Kube-reserved（kube组件保留资源） - system-reserved（系统保留资源） - eviction-threshold（用户设置的驱逐阈值）

 

二、资源预留配置

配置在kubelet服务

1、硬驱逐阈值

--eviction-hard=memory.available<500Mi,nodefs.available<1Gi,imagefs.available<100Gi

当出现MemoryPressure时，Scheduler不会调度新的Best-Effort QoS Pods到此节点。

当出现DiskPressure时，Scheduler不会调度任何新Pods到此节点。

 

2、最小驱逐回收

--eviction-minimum-reclaim="memory.available=500Mi,nodefs.available=500Mi,imagefs.available=2Gi"`

 

3、驱逐等待时间

--eviction-pressure-transition-period=20s

 

4、节点状态更新间隔

--node-status-update-frequency=10s

 

5、设置预留系统服务的资源

--system-reserved=cpu=200m,memory=1G

 

6、用于配置为kube组件（kubelet,kube-proxy,dockerd等）预留的资源量

--kube-reserved=cpu=200m,memory=1G

 

三、调整实例

# vim /usr/lib/systemd/system/kubelet.service
[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=docker.service
Requires=docker.service

[Service]
WorkingDirectory=/var/lib/kubelet
ExecStart=/opt/kubernetes/bin/kubelet 
  --address=10.30.20.44 
  --hostname-override=10.30.20.44 
  --pod-infra-container-image=mirrorgooglecontainers/pause-amd64:3.0 
  --experimental-bootstrap-kubeconfig=/opt/kubernetes/cfg/bootstrap.kubeconfig 
  --kubeconfig=/opt/kubernetes/cfg/kubelet.kubeconfig 
  --cert-dir=/opt/kubernetes/ssl 
  --client-ca-file=/opt/kubernetes/ssl/ca.pem 
  --network-plugin=cni 
  --eviction-hard=memory.available<1600Mi,nodefs.available<5Gi,imagefs.available<5Gi 
  --eviction-minimum-reclaim=memory.available=2000Mi,nodefs.available=10Gi,imagefs.available=10Gi 
  --eviction-pressure-transition-period=20s 
  --node-status-update-frequency=10s 
  --system-reserved=cpu=200m,memory=1G 
  --kube-reserved=cpu=200m,memory=1G 
  --cni-conf-dir=/etc/cni/net.d 
  --cni-bin-dir=/opt/kubernetes/bin/cni 
  --cluster-dns=10.10.0.2 
  --cluster-domain=cluster.local. 
  --hairpin-mode hairpin-veth 
  --allow-privileged=true 
  --anonymous-auth=false 
  --fail-swap-on=false 
  --logtostderr=true 
  --v=2 
  --log-dir=/opt/kubernetes/log 
  --authentication-token-webhook
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

调整前，可分配内存：32841936Ki

Capacity:
 cpu:                16
 ephemeral-storage:  20469Mi
 hugepages-1Gi:      0
 hugepages-2Mi:      0
 memory:             32944336Ki
 pods:               110
Allocatable:
 cpu:                16
 ephemeral-storage:  19316971898
 hugepages-1Gi:      0
 hugepages-2Mi:      0
 memory:             32841936Ki
 pods:               110

调整后，可分配内存：29352811Ki

Capacity:
 cpu:                16
 ephemeral-storage:  20469Mi
 hugepages-1Gi:      0
 hugepages-2Mi:      0
 memory:             32944336Ki
 pods:               110
Allocatable:
 cpu:                15600m
 ephemeral-storage:  15349Mi
 hugepages-1Gi:      0
 hugepages-2Mi:      0
 memory:             29352811Ki
 pods:               110