K8S kubectl高频命令详解
一、kubectl工具介绍
kubectl是Kubernetes集群的命令行工具，通过kubectl能够对集群本身进行管理，对资源的对象进行操作，这些操作包括对资源对象的创建、删除和查看等，并能够在集群上进行容器化应用的安装部署。
中文官网解读：https://www.kubernetes.org.cn/4060.html
二、kubectl常用命令介绍
2.1 Pod、Node与宿主之前网络通信方式
2.2 定义测试pod
方案一：直接定义pod，将容器端口映射到宿主
（1）定义pod
[root@ansible K8S]# vim mysql.yaml apiVersion: v1 kind: Pod metadata: name: mysql-pod namespace: stargao labels: name: mysql-pod spec: containers: - name: mysql55 image: uhub.service.ucloud.cn/library/mysql:5.7.9 env: - name: MYSQL_ROOT_PASSWORD value: redhat - name: MYSQL_USER value: stargao - name: MYSQL_PASSWORD value: redhat ports: - containerPort: 3306 hostPort: 33306 # 映射宿主端口
（2）创建K8S单pod
# 创建pod [root@ansible K8S]# kubectl apply -f mysql.yaml pod/mysql-pod created # 查看pod创建情况 [root@ansible K8S]# kubectl get pod NAME READY STATUS RESTARTS AGE mysql-pod 0/1 ContainerCreating 0 21s [root@ansible K8S]# kubectl get pod NAME READY STATUS RESTARTS AGE mysql-pod 1/1 Running 0 22s
方案二：定义RC与SVC
（1）定义ReplicationController副本控制器，简称RC
[root@ansible K8S]# vim mysql-rc.yaml apiVersion: v1 kind: ReplicationController metadata: name: mysql-rc labels: name: mysql-rc spec: replicas: 3 selector: name: stargao-mysql-template template: metadata: labels: name: stargao-mysql-template spec: containers: - name: stargao-mysql-containers image: uhub.service.ucloud.cn/library/mysql:5.7.9 env: - name: MYSQL_ROOT_PASSWORD value: redhat - name: MYSQL_USER value: stargao - name: MYSQL_PASSWORD value: redhat ports: - containerPort: 3306
（2）定义关联 service，简称SVC
[root@ansible K8S]# vim mysql-svc.yaml apiVersion: v1 kind: Service metadata: name: mysql-svc labels: name: mysql-svc spec: type: NodePort ports: - port: 3306 # pod暴露到集群IP上的端口 targetPort: 3306 # 容器端口 protocol: TCP nodePort: 33306 # 集群IP，映射到node节点(宿主)端口 selector: name: stargao-mysql-template
（3）查看service情况
[root@ansible k8s]# kubectl describe services
Name: mysql-svc
Namespace: stargao
Labels: name=mysql-svc
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"name":"mysql-svc"},"name":"mysql-svc","namespace":"stargao"},"...
Selector: name=stargao-mysql-template
Type: NodePort
IP: 10.2.184.156
Port: <unset> 3306/TCP
TargetPort: 3306/TCP
NodePort: <unset> 33306/TCP
Endpoints: 192.168.0.149:3306,192.168.0.194:3306,192.168.0.212:3306
Session Affinity: None
External Traffic Policy: Cluster（4）创建多副本Pod
# 创建pod [root@ansible K8S]# kubectl apply -f mysql-rc.yaml replicationcontroller/mysql-rc created # 创建SVC [root@ansible K8S]# kubectl apply -f mysql-svc.yaml service/mysql-svc created # 查看pod创建情况 [root@ansible K8S]# kubectl get pod NAME READY STATUS RESTARTS AGE mysql-pod 1/1 Running 0 13h mysql-rc-d4glt 1/1 Running 0 10s mysql-rc-w2kc4 1/1 Running 0 10s mysql-rc-w78jw 1/1 Running 0 10s
2.3 常用命令演示
（1）pod相关操作
# 创建pod [root@ansible K8S]# kubectl apply -f mysql.yaml
# pod日志信息查询 [root@ansible ~]# kubectl logs mysql-pod Initializing database 2021-08-18T15:55:52.474548Z 0 [Warning] InnoDB: New log files created, LSN=45790 2021-08-18T15:55:52.684072Z 0 [Warning] InnoDB: Creating foreign key constraint system tables. 2021-08-18T15:55:52.763803Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: c3fa3f9b-003c-11ec-b1f2-d20a0443d042. 2021-08-18T15:55:52.765482Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened. 2021-08-18T15:55:52.766196Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option. 2021-08-18T15:55:53.465696Z 1 [Warning] 'user' entry 'root@localhost' ignored in --skip-name-resolve mode. 2021-08-18T15:55:53.465755Z 1 [Warning] 'user' entry 'mysql.sys@localhost' ignored in --skip-name-resolve mode. 2021-08-18T15:55:53.465774Z 1 [Warning] 'db' entry 'sys mysql.sys@localhost' ignored in --skip-name-resolve mode. 2021-08-18T15:55:53.465788Z 1 [Warning] 'proxies_priv' entry '@ root@localhost' ignored in --skip-name-resolve mode. 2021-08-18T15:55:53.465822Z 1 [Warning] 'tables_priv' entry 'sys_config mysql.sys@localhost' ignored in --skip-name-resolve mode.
# 查看pod节点运行情况 [root@ansible ~]# kubectl get pod NAME READY STATUS RESTARTS AGE mysql-pod 1/1 Running 0 14h mysql-rc-d4glt 1/1 Running 0 83m mysql-rc-w2kc4 1/1 Running 0 83m mysql-rc-w78jw 1/1 Running 0 83m [root@ansible K8S]# kubectl get pods -o=wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES mysql-rc-d4glt 1/1 Running 0 152m 192.168.0.149 192.168.0.107 <none> <none> mysql-rc-w2kc4 1/1 Running 0 152m 192.168.0.194 192.168.0.107 <none> <none> mysql-rc-w78jw 1/1 Running 0 152m 192.168.0.212 192.168.0.107 <none> <none>
# 查看pod节点详情
[root@ansible ~]# kubectl describe pods
Name: mysql-pod
Namespace: stargao
Priority: 0
PriorityClassName: <none>
Node: 192.168.0.107/192.168.0.107
Start Time: Wed, 18 Aug 2021 23:55:30 +0800
Labels: name=mysql-pod
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"name":"mysql-pod"},"name":"mysql-pod","namespace":"stargao"},"spec...
Status: Running
IP: 192.168.0.3
Containers:
mysql55:
Container ID: containerd://92b8178575d1397b95c4d071b83ce0147c70f8bbdf449b13b972fc217a7ff23e
Image: uhub.service.ucloud.cn/library/mysql:5.7.9
Image ID: uhub.service.ucloud.cn/library/mysql@sha256:cafa4a980ebb935e26f9896895ba6a6e9466c7c33cd172bce1050883300ae30e
Port: 3306/TCP
Host Port: 33306/TCP
State: Running
Started: Wed, 18 Aug 2021 23:55:50 +0800
Ready: True
Restart Count: 0
Environment:
MYSQL_ROOT_PASSWORD: redhat
MYSQL_USER: stargao
MYSQL_PASSWORD: redhat
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-8h5jt (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-8h5jt:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-8h5jt
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300# 删除pod [root@ansible K8S]# kubectl delete -f mysql.yaml pod "mysql-pod" deleted
# 动态查看Pod日志输出 [root@ansible K8S]# kubectl logs -f mysql-pod -c mysql55 语法：kubectl logs –f <pod-name> -c <container-name>
# 查看SVC运行情况 [root@ansible K8S]# kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE mysql-svc NodePort 10.2.184.156 <none> 3306:33306/TCP 11s [root@ansible K8S]# kubectl get svc -o=wide -n stargao NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR mysql-svc NodePort 10.2.184.156 <none> 3306:33306/TCP 82m name=stargao-mysql-template [root@192-168-0-107 ~]# netstat -antulp Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 8794/sshd tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1275/master tcp 0 0 0.0.0.0:33306 0.0.0.0:* LISTEN 9147/kube-proxy
【注】-n指定命名空间；-o=wide输出带有附加信息的纯文本格式。对于Pod对象，将会包含Node名称。
（2）node相关操作
# 查看node运行情况 [root@ansible ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION 192.168.0.107 Ready <none> 28d v1.20.6 192.168.0.220 Ready <none> 28d v1.20.6 192.168.0.48 Ready,SchedulingDisabled master 28d v1.20.6 192.168.0.88 Ready,SchedulingDisabled master 28d v1.20.6 192.168.0.94 Ready,SchedulingDisabled master 28d v1.20.6 [root@ansible K8S]# kubectl get nodes -o=wide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME 192.168.0.107 Ready <none> 28d v1.20.6 192.168.0.107 <none> CentOS Linux 7 (Core) 4.19.0-9.el7.ucloud.x86_64 containerd://1.4.3 192.168.0.220 Ready <none> 28d v1.20.6 192.168.0.220 <none> CentOS Linux 7 (Core) 4.19.0-9.el7.ucloud.x86_64 containerd://1.4.3 192.168.0.48 Ready,SchedulingDisabled master 28d v1.20.6 192.168.0.48 <none> CentOS Linux 7 (Core) 4.19.0-9.el7.ucloud.x86_64 containerd://1.4.3 192.168.0.88 Ready,SchedulingDisabled master 28d v1.20.6 192.168.0.88 <none> CentOS Linux 7 (Core) 4.19.0-9.el7.ucloud.x86_64 containerd://1.4.3 192.168.0.94 Ready,SchedulingDisabled master 28d v1.20.6 192.168.0.94 <none> CentOS Linux 7 (Core) 4.19.0-9.el7.ucloud.x86_64 containerd://1.4.3
# 查看node节点详情
[root@ansible ~]# kubectl describe nodes
Name: 192.168.0.107
Roles: <none>
Labels: UhostID=uhost-pxzclck2
beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/arch=amd64
kubernetes.io/hostname=192.168.0.107
kubernetes.io/os=linux
node.uk8s.ucloud.cn/instance_type=uhost
node.uk8s.ucloud.cn/machine_type=N
node.uk8s.ucloud.cn/resource_id=uhost-pxzclck2
role.node.kubernetes.io/k8s-node=true
topology.kubernetes.io/region=cn-sh2
topology.kubernetes.io/zone=cn-sh2-02
topology.udisk.csi.ucloud.cn/region=cn-sh2
topology.udisk.csi.ucloud.cn/zone=cn-sh2-02
Annotations: csi.volume.kubernetes.io/nodeid: {"udisk.csi.ucloud.cn":"192.168.0.107"}
node.alpha.kubernetes.io/ttl: 0
volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp: Thu, 22 Jul 2021 10:57:11 +0800
Taints: <none>
Unschedulable: false
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
MemoryPressure False Thu, 19 Aug 2021 15:02:38 +0800 Thu, 22 Jul 2021 10:57:11 +0800 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Thu, 19 Aug 2021 15:02:38 +0800 Thu, 22 Jul 2021 10:57:11 +0800 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Thu, 19 Aug 2021 15:02:38 +0800 Thu, 22 Jul 2021 10:57:11 +0800 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Thu, 19 Aug 2021 15:02:38 +0800 Thu, 22 Jul 2021 10:57:21 +0800 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 192.168.0.107
Hostname: 192.168.0.107
Capacity:
cpu: 2
ephemeral-storage: 20470Mi
hugepages-2Mi: 0
memory: 3873420Ki
pods: 110
Allocatable:
cpu: 1800m
ephemeral-storage: 19317915617
hugepages-2Mi: 0
memory: 2719486974
pods: 110
System Info:
Machine ID: 2b2b101ebec37b13cb767b69ceb77af5
System UUID: aaf40fab-d194-4867-82f3-77386b76b8a5
Boot ID: 8a776612-6a3f-4e75-97c9-2f7c7364ab0a
Kernel Version: 4.19.0-9.el7.ucloud.x86_64
OS Image: CentOS Linux 7 (Core)
Operating System: linux
Architecture: amd64
Container Runtime Version: containerd://1.4.3
Kubelet Version: v1.20.6
Kube-Proxy Version: v1.20.6
ProviderID: UCloud://cn-sh2-02//uk8s-2lynocjx-n-39ffh
Non-terminated Pods: (6 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
kube-system coredns-6667d7f4c6-6mjwb 100m (5%) 0 (0%) 70Mi (2%) 170Mi (6%) 28d
kube-system csi-udisk-mzx4k 0 (0%) 0 (0%) 0 (0%) 0 (0%) 28d
stargao mysql-pod 0 (0%) 0 (0%) 0 (0%) 0 (0%) 15h
stargao mysql-rc-d4glt 0 (0%) 0 (0%) 0 (0%) 0 (0%) 105m
stargao mysql-rc-w2kc4 0 (0%) 0 (0%) 0 (0%) 0 (0%) 105m
stargao mysql-rc-w78jw 0 (0%) 0 (0%) 0 (0%) 0 (0%) 105m
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 100m (5%) 0 (0%)
memory 70Mi (2%) 170Mi (6%)
ephemeral-storage 0 (0%) 0 (0%)三、K8S核心组件健康状态
3.1 K8S集群信息查看
# 查看集群信息 [root@ansible K8S]# kubectl cluster-info Kubernetes master is running at https://192.168.0.99:6443 CoreDNS is running at https://192.168.0.99:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
# 查看etcd组件的健康状况
[root@ansible K8S]# kubectl get cs
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
scheduler Healthy ok
etcd-0 Healthy {"health":"true"}
etcd-2 Healthy {"health":"true"}
etcd-1 Healthy {"health":"true"}
【注】etcd 保存了整个集群的状态3.2 K8S核心组件服务运行情况查看
kube-apiserver # 资源对象的唯一操作入口
kube-controller-manager # 集群故障检测和恢复的自动化工作
kube-scheduler # 进行资源调度
etcd # 保存了整个集群的状态
kube-proxy # 写iptables规则
kubelet # 容器的生命周期管理
docker # 容器运行时环境
（1）查看组件运行情况
systemctl status kube-apiserver systemctl status kube-controller-manager systemctl status kube-scheduler systemctl status kube-proxy systemctl status etcd systemctI status docker
（2）查看组件日志信息
journalctl -u kube-apiserver journalctl -u kube-controller-manager journalctl -u kube-scheduler journalctl -u kube-proxy journalctl -u etcd journalctl -u docker
作者：UStarGao
链接：https://www.starcto.com/k8s/211.html
来源：STARCTO
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。
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