常见api

资源对象： pod, replicaset , replicationcontroller, deployment , statefulset , daemonset,
job, cronjob ,horizontalpodautoscaling, node ,namespace, service ,ingress , label , customresourcedefinition 

存储对象： vaume, persistentvoleme, secret ,configmap

策略对象： securitycontext , resourcequota,limitrange

身份对象： serviceaccount ,role, clusterrole 

服务发现与负载均衡: service ingress

查看pod详细信息

[root@kubeadm-master1 namespaces]# kubectl describe pod nginx-deployment-67dfd6c8f9-5s6nz
Name:         nginx-deployment-67dfd6c8f9-5s6nz
Namespace:    default
Priority:     0
Node:         ha2.example.local/192.168.1.214
Start Time:   Thu, 21 Dec 2023 14:11:30 +0800
Labels:       app=nginx
              pod-template-hash=67dfd6c8f9
Annotations:  <none>
Status:       Running
IP:           10.100.4.9
IPs:
  IP:           10.100.4.9
Controlled By:  ReplicaSet/nginx-deployment-67dfd6c8f9
Containers:
  nginx:
    Container ID:   docker://60e1219c96fd4a8a86dcd8fa92197e37607cf416393adf5ed77e79feef7d71ee
    Image:          nginx:1.18.0
    Image ID:       docker-pullable://nginx@sha256:e90ac5331fe095cea01b121a3627174b2e33e06e83720e9a934c7b8ccc9c55a0
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Fri, 22 Dec 2023 10:56:04 +0800
    Last State:     Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Thu, 21 Dec 2023 14:11:37 +0800
      Finished:     Fri, 22 Dec 2023 10:55:19 +0800
    Ready:          True
    Restart Count:  1
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-75cq9 (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-75cq9:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-75cq9
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:          <none>

k8s 基础命令，配置命令，集群管理命令

create/delete/edit/get/describe/logs/exec/scale 增删改查
explain  命令说明

 
Label：给node标记label，实现亲pod与node亲和性 标签管理
apply  动态管理

cluster-info/top  集群状态

node节点管理
cordon：警戒线，标记node不被调度
uncordon：取消警戒标记为cordon的node
drain：驱逐node上的pod,用于node下线等场景
taint：给node标记污点，实现反亲pod与node反亲和性

api-resources/api-versions/version api资源

config 客户端kube-config配置 

yaml 文件必备内容

对象 用k8s是和什么打交道？ K8s 声明式API
 yaml文件 怎么打交道？ 调用声明
必需字段 怎么声明？
1. apiVersion - 创建该对象所使用的 Kubernetes API 的版本
2. kind - 想要创建的对象的类型
3. metadata - 帮助识别对象唯一性的数据，包括一个 name 名称 、
可选的 namespace
4. spec
5. status（Pod创建完成后k8s自动生成status状态

yaml文件及必需字段
每个API对象都有3大类属性：元数据metadata、规范spec和状态status。

spec和status的区别：
spec是期望状态
status是实际状态

查看node详细信息

[root@kubeadm-master1 namespaces]# kubectl describe node kubeadm-master2.example.local
Name:               kubeadm-master2.example.local
Roles:              control-plane,master
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/arch=amd64
                    kubernetes.io/hostname=kubeadm-master2.example.local
                    kubernetes.io/os=linux
                    node-role.kubernetes.io/control-plane=
                    node-role.kubernetes.io/master=
Annotations:        flannel.alpha.coreos.com/backend-data: {"VNI":1,"VtepMAC":"fe:7f:bf:96:44:99"}
                    flannel.alpha.coreos.com/backend-type: vxlan
                    flannel.alpha.coreos.com/kube-subnet-manager: true
                    flannel.alpha.coreos.com/public-ip: 108.181.252.210
                    kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
                    node.alpha.kubernetes.io/ttl: 0
                    volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp:  Wed, 20 Dec 2023 22:18:14 +0800
Taints:             node-role.kubernetes.io/master:NoSchedule
Unschedulable:      false
Lease:
  HolderIdentity:  kubeadm-master2.example.local
  AcquireTime:     <unset>
  RenewTime:       Thu, 28 Dec 2023 23:12:53 +0800
Conditions:
  Type                 Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
  ----                 ------  -----------------                 ------------------                ------                       -------
  NetworkUnavailable   False   Fri, 22 Dec 2023 00:35:46 +0800   Fri, 22 Dec 2023 00:35:46 +0800   FlannelIsUp                  Flannel is running on this node
  MemoryPressure       False   Thu, 28 Dec 2023 23:08:31 +0800   Thu, 21 Dec 2023 12:37:00 +0800   KubeletHasSufficientMemory   kubelet has sufficient memory available
  DiskPressure         False   Thu, 28 Dec 2023 23:08:31 +0800   Thu, 21 Dec 2023 12:37:00 +0800   KubeletHasNoDiskPressure     kubelet has no disk pressure
  PIDPressure          False   Thu, 28 Dec 2023 23:08:31 +0800   Thu, 21 Dec 2023 12:37:00 +0800   KubeletHasSufficientPID      kubelet has sufficient PID available
  Ready                True    Thu, 28 Dec 2023 23:08:31 +0800   Thu, 21 Dec 2023 12:37:00 +0800   KubeletReady                 kubelet is posting ready status
Addresses:
  InternalIP:  192.168.1.210
  Hostname:    kubeadm-master2.example.local
Capacity:
  cpu:                3
  ephemeral-storage:  62450Mi
  hugepages-1Gi:      0
  hugepages-2Mi:      0
  memory:             3879812Ki
  pods:               110
Allocatable:
  cpu:                3
  ephemeral-storage:  58935213983
  hugepages-1Gi:      0
  hugepages-2Mi:      0
  memory:             3777412Ki
  pods:               110
System Info:
  Machine ID:                 718c8cab91d1432b95df7fe5720bc472
  System UUID:                33BAD449-002B-4F38-83B2-6DE6EC2710AD
  Boot ID:                    9d3b25e6-14fd-454f-88a6-beac627dca20
  Kernel Version:             3.10.0-1160.90.1.el7.x86_64
  OS Image:                   CentOS Linux 7 (Core)
  Operating System:           linux
  Architecture:               amd64
  Container Runtime Version:  docker://19.3.15
  Kubelet Version:            v1.20.6
  Kube-Proxy Version:         v1.20.6
PodCIDR:                      10.100.2.0/24
PodCIDRs:                     10.100.2.0/24
Non-terminated Pods:          (6 in total)
  Namespace                   Name                                                     CPU Requests  CPU Limits  Memory Requests  Memory Limits  AGE
  ---------                   ----                                                     ------------  ----------  ---------------  -------------  ---
  kube-flannel                kube-flannel-ds-rbsnd                                    100m (3%)     0 (0%)      50Mi (1%)        0 (0%)         8d
  kube-system                 etcd-kubeadm-master2.example.local                       100m (3%)     0 (0%)      100Mi (2%)       0 (0%)         6d22h
  kube-system                 kube-apiserver-kubeadm-master2.example.local             250m (8%)     0 (0%)      0 (0%)           0 (0%)         6d22h
  kube-system                 kube-controller-manager-kubeadm-master2.example.local    200m (6%)     0 (0%)      0 (0%)           0 (0%)         6d22h
  kube-system                 kube-proxy-89zwn                                         0 (0%)        0 (0%)      0 (0%)           0 (0%)         6d23h
  kube-system                 kube-scheduler-kubeadm-master2.example.local             100m (3%)     0 (0%)      0 (0%)           0 (0%)         6d22h
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource           Requests    Limits
  --------           --------    ------
  cpu                750m (25%)  0 (0%)
  memory             150Mi (4%)  0 (0%)
  ephemeral-storage  100Mi (0%)  0 (0%)
  hugepages-1Gi      0 (0%)      0 (0%)
  hugepages-2Mi      0 (0%)      0 (0%)
Events:              <none>

给node打标签

[root@kubeadm-master1 namespaces]# kubectl label node ha1.example.local group=m43
node/ha1.example.local labeled
[root@kubeadm-master1 namespaces]# kubectl describe node ha1.example.local
Name:               ha1.example.local
Roles:              <none>
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    group=m43

可以利用yaml 文件对这些进行分组指定

kubectl top

[root@kubeadm-master1 namespaces]# kubectl top node
error: Metrics API not available

暂时没有安装插件，自行谷歌

cordon

cordon：警戒线，标记node不被调度
uncordon：取消警戒标记为cordon的node


[root@kubeadm-master1 namespaces]# kubectl get node
NAME                            STATUS   ROLES                  AGE   VERSION
ha1.example.local               Ready    <none>                 8d    v1.20.6
ha2.example.local               Ready    <none>                 8d    v1.20.6
kubeadm-master1.example.local   Ready    control-plane,master   8d    v1.20.6
kubeadm-master2.example.local   Ready    control-plane,master   8d    v1.20.6
kubeadm-master3.example.local   Ready    control-plane,master   8d    v1.20.6
[root@kubeadm-master1 namespaces]# kubectl cordon ha1.example.local
node/ha1.example.local cordoned
[root@kubeadm-master1 namespaces]# kubectl get node
NAME                            STATUS                     ROLES                  AGE   VERSION
ha1.example.local               Ready,SchedulingDisabled   <none>                 8d    v1.20.6
ha2.example.local               Ready                      <none>                 8d    v1.20.6
kubeadm-master1.example.local   Ready                      control-plane,master   8d    v1.20.6
kubeadm-master2.example.local   Ready                      control-plane,master   8d    v1.20.6
kubeadm-master3.example.local   Ready                      control-plane,master   8d    v1.20.6

[root@kubeadm-master1 namespaces]# kubectl get node
NAME                            STATUS   ROLES                  AGE   VERSION
ha1.example.local               Ready    <none>                 8d    v1.20.6
ha2.example.local               Ready    <none>                 8d    v1.20.6
kubeadm-master1.example.local   Ready    control-plane,master   8d    v1.20.6
kubeadm-master2.example.local   Ready    control-plane,master   8d    v1.20.6
kubeadm-master3.example.local   Ready    control-plane,master   8d    v1.20.6

一个服务器下线之前正常操作

先打上cordon 警戒线
然后驱逐pod 
kubectl drain ha1.example.local  --force --ignore-daemonsets
最后这个服务器可以进行下线