kubernetes Node

Node 是 Pod 真正运行的主机，可以物理机，也可以是虚拟机。为了管理 Pod，每个 Node 节点上至少要运行 docker、kubelet 和 kube-proxy 服务。

默认情况下，kubelet 在启动时会向 master 注册自己，并创建 Node 资源。

每个Node都包括以下状态信息

• 地址(Addresses)：包括 hostname、外网 IP 和内网 IP
• 条件(Condition)：包括 OutOfDisk、Ready、MemoryPressure 和 DiskPressure
• 容量(Capacity)：Node 上的可用资源，包括 CPU、内存和 Pod 总数
• 基本信息(Info)：包括内核版本、容器引擎版本、OS 类型等

例如：

$ kubectl describe node 172.20.32.127
Name:               172.20.32.127
Roles:              <none>
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/fluentd-ds-ready=true
                    kubernetes.io/hostname=172.20.32.127
Annotations:        node.alpha.kubernetes.io/ttl=0
                    volumes.kubernetes.io/controller-managed-attach-detach=true
Taints:             <none>
CreationTimestamp:  Sun, 17 Jun 2018 20:46:23 +0800
Conditions:
  Type             Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
  ----             ------  -----------------                 ------------------                ------                       -------
  OutOfDisk        False   Fri, 19 Oct 2018 17:49:36 +0800   Sun, 17 Jun 2018 20:48:57 +0800   KubeletHasSufficientDisk     kubelet has sufficient disk space available
  MemoryPressure   False   Fri, 19 Oct 2018 17:49:36 +0800   Fri, 07 Sep 2018 08:25:56 +0800   KubeletHasSufficientMemory   kubelet has sufficient memory available
  DiskPressure     False   Fri, 19 Oct 2018 17:49:36 +0800   Fri, 07 Sep 2018 08:25:56 +0800   KubeletHasNoDiskPressure     kubelet has no disk pressure
  Ready            True    Fri, 19 Oct 2018 17:49:36 +0800   Fri, 07 Sep 2018 08:25:56 +0800   KubeletReady                 kubelet is posting ready status
Addresses:
  InternalIP:  172.20.32.127
  Hostname:    172.20.32.127
Capacity:
 cpu:     4
 memory:  32946920Ki
 pods:    110
Allocatable:
 cpu:     4
 memory:  32844520Ki
 pods:    110
System Info:
 Machine ID:                 18d66e3d8e761558137b041965257d8b
 System UUID:                18D66E3D-8E76-1558-137B-041965257D8B
 Boot ID:                    9a9e4cf7-97ca-4d3e-99aa-39be7a232901
 Kernel Version:             3.10.0-862.3.2.el7.x86_64
 OS Image:                   CentOS Linux 7 (Core)
 Operating System:           linux
 Architecture:               amd64
 Container Runtime Version:  docker://18.3.0
 Kubelet Version:            v1.9.6
 Kube-Proxy Version:         v1.9.6
PodCIDR:                     192.170.11.0/24
ExternalID:                  172.20.32.127
Non-terminated Pods:         (26 in total)
  Namespace                  Name                                           CPU Requests  CPU Limits  Memory Requests  Memory Limits
  ---------                  ----                                           ------------  ----------  ---------------  -------------
  kube-system                calico-node-xmsj8                              250m (6%)     0 (0%)      0 (0%)           0 (0%)
  kube-system                elasticsearch-fluentd-v2.0.2-2b4bj             100m (2%)     300m (7%)   200Mi (0%)       500Mi (1%)
  kube-system                kube-dns-766cb58688-m59dv                      260m (6%)     0 (0%)      110Mi (0%)       170Mi (0%)
  monitoring                 prometheus-node-exporter-kc27n                 0 (0%)        0 (0%)      0 (0%)           0 (0%)
  st-f1-pack                 bz-bl-mdm-web.7.0.72-jre7-v7n24                0 (0%)        0 (0%)      0 (0%)           0 (0%)
  st-f1-pack                 bz-bl-static-web.7.0.72-jre7-ggb6w             0 (0%)        0 (0%)      0 (0%)           0 (0%)
  st-f1-pack                 bz-blf1-common-web.7.0.72-jre7-8t4qp           0 (0%)        0 (0%)      0 (0%)           0 (0%)
  zabbix                     zabbix-agent-4mwgz                             0 (0%)        0 (0%)      0 (0%)           0 (0%)
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  CPU Requests  CPU Limits  Memory Requests  Memory Limits
  ------------  ----------  ---------------  -------------
  610m (15%)    300m (7%)   310Mi (0%)       670Mi (2%)
Events:         <none>