k8s pod资源配额对调度的影响

1. pod资源配额对调度的影响

• 容器资源限制：

  • resources.limits.cpu

  • resources.limits.memory

• 容器使用的最小资源需求，作为容器调度时资源分配的依据：

  • resources.requests.cpu
  • resources.requests.memory

• 注释：

  ​ CPU单位：可以写m也可以写浮点数，例如0.5=500m，1=1000m

• 参考示例

  apiVersion: v1
  kind: Pod
  metadata:
    name: web
  spec:
    containers:
    - name: web
      image: nginx
      resources:
        requests:              # 启动容器最小资源
          memory: "64Mi"
          cpu: "250m"
        limits:                 # 容器的最大资源限制
          memory: "128Mi"       # 容器的最大资源内存限制128M
          cpu: "500m"           # 容器的最大资源cpu的核数限制，500m=0.5核数
  

• 注释

  1. CPU单位：可以写m也可以写浮点数，例如0.5=500m，1核=1000m

2. 案例

• 编写案例模板

  [root@k8s-master yaml]# vim request-pod.yaml
  [root@k8s-master yaml]# cat request-pod.yaml
  apiVersion: v1
  kind: Pod
  metadata:
    name: web
  spec:
    containers:
    - name: web
      image: nginx
      resources:
        requests:              # 启动容器最小资源
          memory: "64Mi"
          cpu: "250m"
        limits:                 # 容器的最大资源限制
          memory: "128Mi"       # 容器的最大资源内存限制128M
          cpu: "500m"           # 容器的最大资源cpu的核数限制，500m=0.5核数
  
  

• 启动服务

  [root@k8s-master yaml]# kubectl apply -f request-pod.yaml 
  pod/web created
  
  

• 查看服务

  [root@k8s-master yaml]# kubectl get pods
  NAME         READY   STATUS    RESTARTS   AGE
  init-demo    1/1     Running   0          21h
  pod-envars   1/1     Running   2          22h
  probe-demo   1/1     Running   0          24h
  web          1/1     Running   0          14s
  

• 验证服务启动的资源配置限制

  [root@k8s-master yaml]# kubectl describe pods web 
  Name:         web
  Namespace:    default
  Priority:     0
  Node:         k8s-node2/192.168.0.203
  Start Time:   Mon, 30 Nov 2020 15:04:13 +0800
  Labels:       <none>
  Annotations:  cni.projectcalico.org/podIP: 10.244.169.158/32
                cni.projectcalico.org/podIPs: 10.244.169.158/32
  Status:       Running
  IP:           10.244.169.158
  IPs:
    IP:  10.244.169.158
  Containers:
    web:
      Container ID:   docker://f895befae98eedb7fe8fc0b26852afd4023a793b8a7f1abbab7d58851f314651
      Image:          nginx
      Image ID:       docker-pullable://nginx@sha256:6b1daa9462046581ac15be20277a7c75476283f969cb3a61c8725ec38d3b01c3
      Port:           <none>
      Host Port:      <none>
      State:          Running
        Started:      Mon, 30 Nov 2020 15:04:23 +0800
      Ready:          True
      Restart Count:  0
      Limits:
        cpu:     500m
        memory:  128Mi
      Requests:
        cpu:        250m
        memory:     64Mi
      Environment:  <none>
      Mounts:
        /var/run/secrets/kubernetes.io/serviceaccount from default-token-8pppk (ro)
  Conditions:
    Type              Status
    Initialized       True 
    Ready             True 
    ContainersReady   True 
    PodScheduled      True 
  Volumes:
    default-token-8pppk:
      Type:        Secret (a volume populated by a Secret)
      SecretName:  default-token-8pppk
      Optional:    false
  QoS Class:       Burstable
  Node-Selectors:  <none>
  Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                   node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
  Events:
    Type    Reason     Age    From                Message
    ----    ------     ----   ----                -------
    Normal  Scheduled  4m28s  default-scheduler   Successfully assigned default/web to k8s-node2
    Normal  Pulling    4m23s  kubelet, k8s-node2  Pulling image "nginx"
    Normal  Pulled     4m18s  kubelet, k8s-node2  Successfully pulled image "nginx" in 4.71128787s
    Normal  Created    4m18s  kubelet, k8s-node2  Created container web
    Normal  Started    4m18s  kubelet, k8s-node2  Started container web
  

• 怎么查看node节点资源配额

  [root@k8s-master pod]# kubectl  describe node k8s-node01 
  Name:               k8s-node01
  Roles:              <none>
  Labels:             beta.kubernetes.io/arch=amd64
                      beta.kubernetes.io/os=linux
                      kubernetes.io/arch=amd64
                      kubernetes.io/hostname=k8s-node01
                      kubernetes.io/os=linux
  Annotations:        kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
                      node.alpha.kubernetes.io/ttl: 0
                      projectcalico.org/IPv4Address: 172.17.0.13/20
                      projectcalico.org/IPv4IPIPTunnelAddr: 10.244.85.192
                      volumes.kubernetes.io/controller-managed-attach-detach: true
  CreationTimestamp:  Wed, 04 Aug 2021 14:31:44 +0800
  Taints:             <none>
  Unschedulable:      false
  Lease:
    HolderIdentity:  k8s-node01
    AcquireTime:     <unset>
    RenewTime:       Mon, 16 Aug 2021 22:33:39 +0800
  Conditions:
    Type                 Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
    ----                 ------  -----------------                 ------------------                ------                       -------
    NetworkUnavailable   False   Wed, 04 Aug 2021 14:35:31 +0800   Wed, 04 Aug 2021 14:35:31 +0800   CalicoIsUp                   Calico is running on this node
    MemoryPressure       False   Mon, 16 Aug 2021 22:28:53 +0800   Wed, 04 Aug 2021 14:31:44 +0800   KubeletHasSufficientMemory   kubelet has sufficient memory available
    DiskPressure         False   Mon, 16 Aug 2021 22:28:53 +0800   Wed, 04 Aug 2021 14:31:44 +0800   KubeletHasNoDiskPressure     kubelet has no disk pressure
    PIDPressure          False   Mon, 16 Aug 2021 22:28:53 +0800   Wed, 04 Aug 2021 14:31:44 +0800   KubeletHasSufficientPID      kubelet has sufficient PID available
    Ready                True    Mon, 16 Aug 2021 22:28:53 +0800   Wed, 04 Aug 2021 14:34:45 +0800   KubeletReady                 kubelet is posting ready status
  Addresses:
    InternalIP:  172.17.0.13
    Hostname:    k8s-node01
  Capacity:
    cpu:                2
    ephemeral-storage:  51473868Ki
    hugepages-1Gi:      0
    hugepages-2Mi:      0
    memory:             3880180Ki
    pods:               110
  Allocatable:
    cpu:                2
    ephemeral-storage:  47438316671
    hugepages-1Gi:      0
    hugepages-2Mi:      0
    memory:             3777780Ki
    pods:               110
  System Info:
    Machine ID:                 96285cf085224a608d1d6ad0cbf21e97
    System UUID:                96285CF0-8522-4A60-8D1D-6AD0CBF21E97
    Boot ID:                    c84c93c7-eb6f-4e92-884b-01c8eddfb4f8
    Kernel Version:             3.10.0-1160.11.1.el7.x86_64
    OS Image:                   CentOS Linux 7 (Core)
    Operating System:           linux
    Architecture:               amd64
    Container Runtime Version:  docker://20.10.8
    Kubelet Version:            v1.19.0
    Kube-Proxy Version:         v1.19.0
  PodCIDR:                      10.244.1.0/24
  PodCIDRs:                     10.244.1.0/24
  Non-terminated Pods:          (4 in total)
    Namespace                   Name                                        CPU Requests  CPU Limits  Memory Requests  Memory Limits  AGE
    ---------                   ----                                        ------------  ----------  ---------------  -------------  ---
    kube-system                 calico-kube-controllers-5f6cfd688c-pg27v    0 (0%)        0 (0%)      0 (0%)           0 (0%)         12d
    kube-system                 calico-node-xdc7h                           250m (12%)    0 (0%)      0 (0%)           0 (0%)         12d
    kube-system                 coredns-6d56c8448f-msj5b                    100m (5%)     0 (0%)      70Mi (1%)        170Mi (4%)     11d
    kube-system                 kube-proxy-mcnn7                            0 (0%)        0 (0%)      0 (0%)           0 (0%)         12d
  Allocated resources:
    (Total limits may be over 100 percent, i.e., overcommitted.)
    Resource           Requests    Limits
    --------           --------    ------
    cpu                350m (17%)  0 (0%)
    memory             70Mi (1%)   170Mi (4%)
    ephemeral-storage  0 (0%)      0 (0%)
    hugepages-1Gi      0 (0%)      0 (0%)
    hugepages-2Mi      0 (0%)      0 (0%)
  Events:              <none>