一、kubectl命令详解
1、查看某个资源的详细信息：kubectl describe pod pod_name -n nameapace
[root@master ~]# kubectl describe pods -n kube-public
### 查看指定命名空间中的pod的详细信息
Name: nginx-w1-7464d66457-psk6h
Namespace: kube-public
Priority: 0
Node: node01/192.168.159.11
Start Time: Wed, 02 Nov 2022 01:40:47 +0800
Labels: app=nginx-w1
pod-template-hash=7464d66457
Annotations: <none>
Status: Running
IP: 10.150.1.3
IPs:
IP: 10.150.1.3
Controlled By: ReplicaSet/nginx-w1-7464d66457
Containers:
nginx:
Container ID: docker://4011df060a9ad777793f061675fc1a784f4effe56f5585d91d5ba3670660c620
Image: nginx
Image ID: docker-pullable://nginx@sha256:943c25b4b66b332184d5ba6bb18234273551593016c0e0ae906bab111548239f
Port: <none>
Host Port: <none>
State: Running
Started: Wed, 02 Nov 2022 01:41:06 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-llzgh (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-llzgh:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
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>
Name: nginx-x1-77484d895f-ddhqt
Namespace: kube-public
Priority: 0
Node: node02/192.168.159.13
Start Time: Thu, 03 Nov 2022 16:16:11 +0800
Labels: app=nginx-x1
pod-template-hash=77484d895f
Annotations: <none>
Status: Running
IP: 10.150.2.3
IPs:
IP: 10.150.2.3
Controlled By: ReplicaSet/nginx-x1-77484d895f
Containers:
nginx:
Container ID: docker://ecc07803682f2d7a51037024354dae0d190841443121ca0a8514ab224179cbf5
Image: nginx:latest
Image ID: docker-pullable://nginx@sha256:943c25b4b66b332184d5ba6bb18234273551593016c0e0ae906bab111548239f
Port: <none>
Host Port: <none>
State: Running
Started: Thu, 03 Nov 2022 16:16:36 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-47hxr (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-47hxr:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
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>
2、查看指定命名空间中pod的基本信息：kubectl get pods -n namespace
[root@master ~]# kubectl get pods -n kube-public
NAME READY STATUS RESTARTS AGE
nginx-w1-7464d66457-psk6h 1/1 Running 0 43h
nginx-x1-77484d895f-ddhqt 1/1 Running 0 5h12m
3、跨主机登录容器：kubectl exec -it pod_name /bin/bash -n namespace
root@master ~]# kubectl exec -it nginx-x1-77484d895f-ddhqt /bin/bash -n kube-public
[root@master ~]# kubectl exec -it nginx-x1-77484d895f-ddhqt /bin/bash -n kube-public
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@nginx-x1-77484d895f-ddhqt:/#
4、删除pod
4.1、直接删除pod。但是deployment，副本控制器还在，他就会自己再创建一个。
[root@master ~]# kubectl delete pod nginx- -n kube-public
pod "nginx-w1-7464d66457-psk6h" deleted
①、直接删除POD
②、查看，发现与原先pod_name不一样，
4.2、删除pod副本控制器deployment:
[root@master ~]# kubectl delete deployment nginx-w1 -n kube-public
4.3、如果删除过程中出现幺蛾子，Pod无法删除，总是处于terminating状态，则执行强行删除--force --grace-period=0
5、命令行扩容和缩容
5.1、副本集的扩容
①查看原有副本集：1个
②扩容副本集为4
5.2、副本集的缩容
基于上面结果进行实验，设置--replicas=2，指定副本集数量后，他会根据现有的副本集数量和期望值相比较，从而决定时扩容还是缩容
6、删除service
[root@master ~]# kubectl delete svc nginx-server -n default
[root@master ~]# kubectl get svc -n default
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.125.0.1 <none> 443/TCP 2d6h
nginx-server NodePort 10.125.126.34 <none> 80:30537/TCP 45m
nginx1-server NodePort 10.125.103.25 <none> 80:31070/TCP 2m41s
[root@master ~]# kubectl delete svc nginx-server -n default
service "nginx-server" deleted
7、查看pod网络状态详情信息和service暴露的端口
[root@master ~]# kubectl get svc,pods -n default
8、查看关联后的节点
[root@master ~]# kubectl get endpoints
[root@master ~]# kubectl get endpoints
NAME ENDPOINTS AGE
kubernetes 192.168.159.10:6443 2d6h
nginx1-service 10.150.1.10:80,10.150.1.9:80,10.150.2.9:80 32m
9、查看service的描述信息
[root@master ~]# kubectl describe svc nginx
[root@master ~]# kubectl describe svc nginx
Name: nginx1-service
Namespace: default
Labels: app=nginx
Annotations: <none>
Selector: app=nginx
Type: NodePort
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.125.32.0
IPs: 10.125.32.0
Port: <unset> 80/TCP
TargetPort: 80/TCP
NodePort: <unset> 31625/TCP
Endpoints: 10.150.1.10:80,10.150.1.9:80,10.150.2.9:80
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
10、核心组件查看日志
通过kubeadm方式部署的K8S
kubectl logs -f pod_name -n namespace 或者 journalctl -u kubelet -f
通过二进制部署的K8S
journalctl -u kubelet -f
二、pod的生命周期
pod生命周期是指：pod在从创建到删除过程中，所包含、经历的状态
pod的类型分为2中：
①、自主式：没有控制器管理的就是自助式的。删除时直接删除就行
②、申明式：有控制器管理的Pod。(我们一般使用的类型)
1、创建一个Pod，启动nginx实例，暴露容器80端口，设置副本集为3（创建pod）
namespace为默认
[root@master ~]# kubectl create deployment nginx-ceshi --image=nginx:1.14 --port 80 --replicas=3
deployment.apps/nginx-ceshi created
2、 发布：kubectl expose命令
3、 查看端口
三、 service的type类型
①、clusterIP:提供一个集群内部的虚拟IP以供Pod访问(service默认类型)
②、NodePort:在每个Node上打开一个端口以供外部访问，Kubernetes将会在每个Node上打开一个端口并且每个Node的端口都是一样的，通过 NodeIp:NodePort 的方式Kubernetes集群外部的程序可以访问service。每个端口只能是一种服务，端口范围只能是30000-32767
③、LoadBalancer:通过设置LoadBalancer映射到云服务商提供的LoadBalancer地址。这种用法仅用于在公有云服务提供商的云平台上设置service的场景。通过外部的负载均衡器来访问，通常在云平台部署LoadBalancer还需要额外的费用。
④、externalName:将service名称映射到一个DNS域名上，相当于DNS服务的CNAME记录，用于让Pod去访问集群外部的资源，它本身没有绑定任何的资源。
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