kubernetes基础介绍及有关命令
kubernetes基础介绍及有关命令
k8s的pod分类
pod分为两类：
自主式pod
控制器管理的pod
自主式pod由k8s管理器进行管理，而static pod由kubelet进行创建与管理
自主式pod
自主式pod总是在前台运行，同时接受k8s管理与调度，当集群当中的pod因为某种原因停止，k8s会根据其副本的数量，重新的生成对应的pod
自我管理的pod，创建以后仍然需要提交给apiserver，由apiserver接收以后借助于调度器将其调度至指定的node节点，由node启动此pod
如果此pod出现故障,需要重启容器则由kubelet来完成 如果node节点故障了，那么此pod将会消失。其无法实现全局调度。所以不推荐使用此种pod
控制器管理的pod
常见的pod控制器：
ReplicationController：当启动一个pod时。这个pod如果不够用可以再启个副本，而后由控制器来管理同一类pod的各种副本与对象。一旦副本少了就会自动增加。采取多退少补的规则，精确符合我们所定义的期望。支持滚动更新
ReplicaSet：由一个名叫Deployment的声明式更新的控制器来管理
Deployment：Deployment只能管理无状态的应用
StateFulSet：有状态副本集，可以管理有状态的应用
DaemonSet：如果需要在每个node上运行一个副本的时候可以用DaemonSet
核心主键
HPA
Deployment还支持二级控制器，HPA(HorizontalPodAutoscaler，水平pod自动伸缩控制器)，一般情况下我们可以确保一个node上有2个pod在运行，万一用户访问流量增加，2个pod不足以承载这么多访问量怎么办?此时我们就应该要增加pod资源，那么到底应该加几个?
HPA控制器可自动监控pod、自动进行扩展。
service
假如有2个pod,pod有其生命周期,万一pod所在的节点宕机了，那么此pod将应该要在其他的节点上重建,而重建完的pod与原来的pod已经不是同一个pod了，只是两者都是运行的同一个服务而已。且每个容器都有其IP地址，重建的pod中的容器其IP地址与之前的pod中容器的IP地址是不一样的,如此一来就会存在一个问题,客户端如何访问这些pod中的容器呢?(会转换到另一个节点去运行)
用于做服务发现，pod是有生命周期的，一个pod随时都有可能离去，随时都有可能会有其他内pod加进来，假如它们提供的是同一种服务，客户端是无法通过固定的手段来访问这些pod的，因为pod本身是不固定的，它们随时可能被替换掉,无论使用主机名还是IP地址，都随时会被替换掉。
为了尽可能的降低客户端与pod间协调的复杂度，k8s为每一组提供同类服务的pod和其客户端之间添加了一个中间层，这个中间层是固定的,这个中间层就叫service。
service只要不被删除，其地址与名称皆是固定的,当客户端需要在其配置文件中写上访问某个服务时,它不再需要自动发现，只需要在配置文件中写明service的名称即可，而这个service是个调度器，其不但能够提供一个稳定的访问入口，还可以做反向代理，当service接收到客户端的请求后，会将其代理到后端的pod之上，一旦pod宕机了会立即新建一个pod，这个新建的pod会立即被service关联上，作为service后端的可用pod之一
客户端程序访问服务都是通过IP+端口或者主机名+端口的方式来实现的。而service关联后端的pod不是靠它的IP和主机名，而是靠pod的标签选择器。只要创建的pod的label是统一的，无论IP地址和主机如何改变，其都能被service所识别。如此一来,只要pod属于标签选择器，只要其在service的管理范围之内，则其就会被关联到service中，当这个动态的pod关联到service中之后，再进行动态的探测此pod的IP地址、端口，再将其作为自己后端可调度的可用服务蒂王机为象。因此，客户端的请求发送到service，然后由service代理到后端真实的pod中的容器进行响应。
service不是一个程序，也不是一个组件，它只是一个iptables的dnat规则,service作为k8s的对象,有其自身的名称，而service的名称相当于服务的名称,而这个名称可以被解析。
AddOns附件
dns pod:装完k8s后第一件事就需要在k8s集群上部署一个dns pod，以确保各service的名称能够被解析可以动态改变，包括动态创建、动态删除、动态修改,比如把service的名称改了,dnspod会自动触发，将dns解析记录中的名称也给改掉;假如我们手动把service的ip地址给改了,改完以后会自动触发,将dns服务中的解析记录给改掉。如此一来，客户端去访问pod资源的时候可以直接访问service的名称,然后由集群中专用的dns服务来负责解析。
这种pod是k8s自身的服务就需要用到的pod，所以我们把它称为基础性的系统架构级的pod对象,而且它们也被称为集群附件
网络模型
三种网络模型
- 节点网络
- service集群网络
- pod网络
同节点Pod之间的通信
在容器启动前，会为容器创建一个虚拟Ethernet接口对，这个接口对类似于管道的两端，其中一端在主机命名空间中，另外一端在容器命名空间中，并命名为eth0。在主机命名空间的接口会绑定到网桥。网桥的地址段会取IP赋值给容器的eth0接口。
不同节点上的Pod通信
我们已经知道一个节点上的容器都会连接到同一网桥，因此要让运行在不同节点上的容器之间能够通信，这些节点的网桥就需要以某种方式连接起来。 跨整个集群的Pod的IP地址必须是唯一的，所有跨节点的网桥必须使用不重叠的网络地址段，以防止不同节点上的Pod拿到同一IP地址，即确保没有IP地址冲突。
发送到B节点上的容器时，报文会先通过veth接口对到网桥，再由网桥到A节点的物理适配器，再通过网线传输到B节点的物理适配器，再通过B的网桥，经过接口对到达目标容器。
注意：上述情形仅在节点连接到相同网关，之间没有任何路由设备时有效。否则，路由设备会因为IP私有产生丢包现象，除非设置路由规则。但随着节点的增加，路由的配置会变得非常困难。因此我们使用SDN（软件定义网络）技术来简化此类问题，SDN可以忽略底层网络拓扑，使其就像连接到同一网关。
Pod与Service
在不同节点上的Pod通信中，我们知道了Pod是以IP地址进行通信，但Kubernetes 的集群中， Pod 可能会频繁的销毁和创建，也就是说 Pod 的 IP 不是固定的。 为了解决这个问题，Service 提供了访问 Pod 的抽象层，即为一组功能相同的Pod提供单一不变的接入点资源。 无论后端的 Pod 如何变化，Service 都作为稳定的前端对外提供服务。 同时，Service 还提供了高可用和负载均衡功能，Service 负责将请求转发给正确的 Pod。
kubectl常用命令
语法
kubectl [command] [TYPE] [NAME] [flags]
command：子命令
TYPE：资源类型
NAME：资源名称
flags：命令参数
命令帮助
kubectl命令的帮助很详细，kubectl -h会列出所有的子命令，在任何子命令后跟 -h，都会输出详细的帮助以及用例，遇到问题可以随时查看帮助。
资源对象
kubectl大部分子命令后都可以指定要操作的资源对象，可以用kubectl api-resources命令参考
全局参数
kubectl options命令可以列出可以全局使用的命令参数
--cluster='': 指定命令操作对象的集群
--context='': 指定命令操作对象的上下文
-n, --namespace='': 指定命令操作对象的Namespace
create
从文件或标准输出中创建pod
# 创建一个deployment类型的pos,名字是nginx1，使用的镜像是nginx
[root@master ~]# kubectl create deployment wb1 --image=nginx
deployment.apps/wb1 created
[root@master ~]# kubectl create deployment nginx1 --image=nginx
deployment.apps/nginx1 created
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 40s
# 创建deployment类型的pos,名字是nginx2，使用的镜像是nginx，replicas是指定创建的个数
[root@master ~]# kubectl create deployment nginx2 --image=nginx --replicas=2
deployment.apps/nginx2 created
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 3m2s
nginx2-85bf7b8976-68q5d 0/1 ContainerCreating 0 42s
nginx2-85bf7b8976-74l6z 1/1 Running 0 42s
run
在集群中运行一个指定的镜像的pod(自主式pod)
[root@master ~]# kubectl run nginx --image nginx
pod/nginx created
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 0/1 ContainerCreating 0 11s
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 0/1 ContainerCreating 0 11s
wb1-5dbfb96758-hhfhb 1/1 Running 0 16m
[root@master ~]# kubectl run nginx1 --image=nginx --labels="app=web"
pod/nginx1 created
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 2m9s
nginx1 1/1 Running 0 18s
[root@master ~]# kubectl run nginx2 --image=nginx --labels="app=web"
pod/nginx2 created
[root@master ~]# kubectl run nginx3 --image=nginx --labels="app=web"
pod/nginx3 created
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 5m49s
nginx1 1/1 Running 0 3m58s
nginx2 1/1 Running 0 73s
nginx3 1/1 Running 0 43s
[root@master ~]# kubectl delete pod -l app=web
pod "nginx1" deleted
pod "nginx2" deleted
pod "nginx3" deleted
[root@master ~]# kubectl run web123 --image=nginx --dry-run=client
pod/web123 created (dry run)
[root@master ~]# kubectl run -i -t web123 --image=busybox --restart=Never
If you don't see a command prompt, try pressing enter.
/ # ls -l
total 16
drwxr-xr-x 2 root root 12288 Dec 7 00:20 bin
drwxr-xr-x 5 root root 380 Dec 19 10:22 dev
drwxr-xr-x 1 root root 66 Dec 19 10:22 etc
drwxr-xr-x 2 nobody nobody 6 Dec 7 00:20 home
dr-xr-xr-x 219 root root 0 Dec 19 10:22 proc
drwx------ 1 root root 26 Dec 19 10:22 root
dr-xr-xr-x 13 root root 0 Dec 19 10:21 sys
drwxrwxrwt 2 root root 6 Dec 7 00:20 tmp
drwxr-xr-x 3 root root 18 Dec 7 00:20 usr
drwxr-xr-x 1 root root 17 Dec 19 10:22 var
delete
删除资源的文件名，标准输出，资源和名称，或资源和标签选择器
[root@master ~]# kubectl get pods,svc
NAME READY STATUS RESTARTS AGE
pod/nginx-85b98978db-dgkbp 1/1 Running 0 97m
pod/nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 11m
pod/nginx2-85bf7b8976-68q5d 1/1 Running 0 9m8s
pod/nginx2-85bf7b8976-74l6z 1/1 Running 0 9m8s
pod/nginx3-59475d8756-l8mcq 1/1 Running 0 7m17s
pod/wb1-5dbfb96758-hhfhb 1/1 Running 0 11m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 144m
service/nginx NodePort 10.105.224.204 <none> 80:31753/TCP 97m
[root@master ~]# kubectl delete deployment,svc nginx
deployment.apps "nginx" deleted
service "nginx" deleted
[root@master ~]# kubectl get pods,svc
NAME READY STATUS RESTARTS AGE
pod/nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 13m
pod/nginx2-85bf7b8976-68q5d 1/1 Running 0 10m
pod/nginx2-85bf7b8976-74l6z 1/1 Running 0 10m
pod/nginx3-59475d8756-l8mcq 1/1 Running 0 8m50s
pod/wb1-5dbfb96758-hhfhb 1/1 Running 0 13m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 146m
get
查看创建的pod
[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-85b98978db-dgkbp 1/1 Running 0 90m
nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 5m2s
nginx2-85bf7b8976-68q5d 1/1 Running 0 2m42s
nginx2-85bf7b8976-74l6z 1/1 Running 0 2m42s
nginx3-59475d8756-l8mcq 1/1 Running 0 51s
wb1-5dbfb96758-hhfhb 1/1 Running 0 5m14s
[root@master ~]# kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 138m
nginx NodePort 10.105.224.204 <none> 80:31753/TCP 91m
[root@master ~]# kubectl get service,pod
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 138m
service/nginx NodePort 10.105.224.204 <none> 80:31753/TCP 91m
NAME READY STATUS RESTARTS AGE
pod/nginx-85b98978db-dgkbp 1/1 Running 0 91m
pod/nginx1-5c9f6bbd8c-2ng6h 1/1 Running 0 5m52s
pod/nginx2-85bf7b8976-68q5d 1/1 Running 0 3m32s
pod/nginx2-85bf7b8976-74l6z 1/1 Running 0 3m32s
pod/nginx3-59475d8756-l8mcq 1/1 Running 0 101s
pod/wb1-5dbfb96758-hhfhb 1/1 Running 0 6m4s
[root@master ~]# kubectl get ns
NAME STATUS AGE
default Active 139m
kube-node-lease Active 139m
kube-public Active 139m
kube-system Active 139m
[root@master ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx 1/1 1 1 93m
nginx1 1/1 1 1 7m49s
nginx2 2/2 2 2 5m29s
nginx3 1/1 1 1 3m38s
wb1 1/1 1 1 8m1s
[root@master ~]# kubectl get deployment nginx
NAME READY UP-TO-DATE AVAILABLE AGE
nginx 1/1 1 1 94m
Kubectl常用命令的使用
explain
获取资源
用法：
kubectl explain RESOURCE
//获取资源及其字段的文档
[root@master ~]# kubectl explain pods
KIND: Pod
VERSION: v1
DESCRIPTION:
Pod is a collection of containers that can run on a host. This resource is
created by clients and scheduled onto hosts.
FIELDS:
apiVersion <string>
APIVersion defines the versioned schema of this representation of an
object. Servers should convert recognized schemas to the latest internal
value, and may reject unrecognized values. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources
kind <string>
Kind is a string value representing the REST resource this object
represents. Servers may infer this from the endpoint the client submits
requests to. Cannot be updated. In CamelCase. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds
metadata <Object>
Standard object's metadata. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
spec <Object>
Specification of the desired behavior of the pod. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
status <Object>
Most recently observed status of the pod. This data may not be up to date.
Populated by the system. Read-only. More info:
https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
edit
编辑资源
//运行一个pod类型的nginx，名字叫nginx,内型是deployment
[root@master ~]# kubectl create deployment nginx --image nginx
deployment.apps/nginx created
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-cpbg4 0/1 ContainerCreating 0 10s
//使用edit命令编辑
[root@master ~]# kubectl edit deployment nginx
......
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
creationTimestamp: "2021-12-20T10:33:49Z"
generation: 1
labels:
app: nginx
name: jjyy #添加name: jjyy
.....
//查看
[root@master ~]# kubectl describe deploy nginx
Name: nginx
Namespace: default
CreationTimestamp: Mon, 20 Dec 2021 18:33:49 +0800
Labels: app=nginx
name=jjyy
Annotations: deployment.kubernetes.io/revision: 1
Selector: app=nginx
Replicas: 1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
......
scale
动态扩展
//使用scale扩展
[root@master ~]# kubectl scale deployment/nginx --replicas 3
deployment.apps/nginx scaled
//扩展后查看多了几个相同类型的pod
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-8bnn8 1/1 Running 0 37s
nginx-6799fc88d8-cpbg4 1/1 Running 0 15m
nginx-6799fc88d8-t6vpw 1/1 Running 0 37s
//如果只需要2个deployment类型的nginx的pod
[root@master ~]# kubectl scale deployment/nginx --replicas 2
deployment.apps/nginx scaled
//查看发现只有两个（删除是随机的）
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-8bnn8 1/1 Running 0 3m22s
nginx-6799fc88d8-cpbg4 1/1 Running 0 18m
autoscale
自动扩展，给定一个范围，自动根据业务的访问量增加或减少
//最少3个，当不满足条件时会自动创建
[root@master ~]# kubectl autoscale deployment/nginx --min 3 --max=5
horizontalpodautoscaler.autoscaling/nginx autoscaled
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-8bnn8 1/1 Running 0 8m1s
nginx-6799fc88d8-cpbg4 1/1 Running 0 23m
nginx-6799fc88d8-ctjmt 0/1 ContainerCreating 0 4s
//当大于5个时，先创建，之后也会随机删除，直到满足条件五个
[root@master ~]# kubectl scale deployment/nginx --replicas 7
deployment.apps/nginx scaled
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-84mfw 1/1 Running 0 52s
nginx-6799fc88d8-8bnn8 1/1 Running 0 20m
nginx-6799fc88d8-cpbg4 1/1 Running 0 35m
nginx-6799fc88d8-ctjmt 1/1 Running 0 12m
nginx-6799fc88d8-jzksn 0/1 Terminating 0 52s
nginx-6799fc88d8-rf74m 1/1 Running 0 52s
nginx-6799fc88d8-swjv9 0/1 Terminating 0 52s
cluster-info
显示集群信息
[root@master ~]# kubectl cluster-info
Kubernetes control plane is running at https://192.168.145.250:6443
KubeDNS is running at https://192.168.145.250:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
cordon
可调度
[root@master ~]# kubectl cordon node2
node/node2 already cordoned
[root@master ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
master Ready control-plane,master 2d4h v1.20.0
node1 NotReady <none> 2d4h v1.20.0
node2 Ready,SchedulingDisabled <none> 2d4h v1.20.0
[root@master ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-6799fc88d8-cpbg4 1/1 Running 0 132m 10.244.1.24 node1 <none> <none>
nginx-6799fc88d8-plvhf 1/1 Running 0 95m 10.244.1.31 node1 <none> <none>
nginx-6799fc88d8-rf74m 1/1 Running 1 97m 10.244.2.4 node2 <none>
[root@master ~]# kubectl scale deployment/nginx --replicas 2
[root@master ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-6799fc88d8-9wk4h 0/1 Pending 0 3m46s <none> <none> <none> <none>
nginx-6799fc88d8-cpbg4 1/1 Terminating 0 138m 10.244.1.24 node1 <none> <none>
nginx-6799fc88d8-plvhf 1/1 Terminating 0 101m 10.244.1.31 node1 <none> <none>
nginx-6799fc88d8-rf74m 1/1 Running 1 103m 10.244.2.4 node2 <none> <none>
nginx-6799fc88d8-snm2v 0/1 Pending 0 16s <none> <none> <none>
uncordon
不可调度
[root@master ~]# kubectl uncordon node2
node/node2 uncordoned
[root@master ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
master Ready control-plane,master 2d4h v1.20.0
node1 NotReady <none> 2d4h v1.20.0
node2 Ready <none> 2d4h v1.20.0
[root@master ~]# kubectl create deployment nginx2 --image nginx
deployment.apps/nginx2 created
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-9wk4h 1/1 Running 0 8m22s
nginx-6799fc88d8-cpbg4 1/1 Terminating 0 143m
nginx-6799fc88d8-plvhf 1/1 Terminating 0 106m
nginx-6799fc88d8-rf74m 1/1 Running 1 108m
nginx-6799fc88d8-snm2v 1/1 Running 0 4m52s
nginx2-5fc4444698-bf76p 1/1 Running 0 25s
[root@master ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-6799fc88d8-9wk4h 1/1 Running 0 8m59s 10.244.2.5 node2 <none> <none>
nginx-6799fc88d8-cpbg4 1/1 Terminating 0 143m 10.244.1.24 node1 <none> <none>
nginx-6799fc88d8-plvhf 1/1 Terminating 0 106m 10.244.1.31 node1 <none> <none>
nginx-6799fc88d8-rf74m 1/1 Running 1 109m 10.244.2.4 node2 <none> <none>
nginx-6799fc88d8-snm2v 1/1 Running 0 5m29s 10.244.2.6 node2 <none> <none>
nginx2-5fc4444698-bf76p 1/1 Running 0 62s 10.244.2.7 node2 <none> <none>
describe
显示指定pod的详细信息
[root@master ~]# kubectl describe pod nginx
Name: nginx-6799fc88d8-cpbg4
Namespace: default
Priority: 0
Node: node1/192.168.129.135
Start Time: Mon, 20 Dec 2021 18:33:49 +0800
Labels: app=nginx
pod-template-hash=6799fc88d8
Annotations: <none>
Status: Running
IP: 10.244.1.24
......
logs
查看日志
[root@master ~]# kubectl logs deployment/nginx
......
2021/12/20 10:34:05 [notice] 1#1: start worker processes
2021/12/20 10:34:05 [notice] 1#1: start worker process 32
2021/12/20 10:34:05 [notice] 1#1: start worker process 33
/docker-entrypoint.sh: Configuration complete; ready for start up
[root@master ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 2d4h
nginx ClusterIP 10.102.213.63 <none> 8080/TCP 24h
[root@master ~]# curl 10.102.213.63:8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
[root@master ~]# kubectl logs deployment/nginx
......
2021/12/20 12:44:49 [notice] 1#1: start worker processes
2021/12/20 12:44:49 [notice] 1#1: start worker process 31
2021/12/20 12:44:49 [notice] 1#1: start worker process 32
10.244.0.0 - - [20/Dec/2021:13:04:14 +0000] "GET / HTTP/1.1" 200 615 "-" "curl/7.61.1" "-"
10.244.0.0 - - [20/Dec/2021:13:05:26 +0000] "GET / HTTP/1.1" 200 615 "-" "curl/7.61.1" "-"
attach
附加在一个容器里
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-cpbg4 1/1 Running 0 43m
nginx-6799fc88d8-plvhf 1/1 Running 0 6m38s
nginx-6799fc88d8-rf74m 1/1 Running 0 8m57s
[root@master ~]# kubectl attach nginx-6799fc88d8-cpbg4
Defaulting container name to nginx.
Use 'kubectl describe pod/nginx-6799fc88d8-cpbg4 -n default' to see all of the containers in this pod.
If you don't see a command prompt, try pressing enter.
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exec
执行容器命令
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-6799fc88d8-cpbg4 1/1 Running 0 45m
nginx-6799fc88d8-plvhf 1/1 Running 0 8m2s
nginx-6799fc88d8-rf74m 1/1 Running 0 10m
[root@master ~]# kubectl exec nginx-6799fc88d8-cpbg4 -- date
Mon Dec 20 11:20:02 UTC 2021
[root@master ~]# kubectl exec -it nginx-6799fc88d8-cpbg4 -- /bin/sh
# ls
bin dev docker-entrypoint.sh home lib64 mnt proc run srv tmp var
boot docker-entrypoint.d etc lib media opt root sbin sys usr
# exit
[root@master ~]#
prot-forward
转发一个或多个端口到pod里面去
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
web-96d5df5c8-8fzdv 1/1 Running 0 17s
[root@master ~]# kubectl port-forward deployment/web 80 #可以变成':80'（随机一个端口号，只能本机访问）或者变成指定的端口号'8080:80'(本机访问用80，其它主机访问就可以用8080)
Forwarding from 127.0.0.1:80 -> 80
Forwarding from [::1]:80 -> 80
[root@master ~]# ss -anlt
State Recv-Q Send-Q Local Address:Port Peer Address:Port
...... 0.0.0.0:*
LISTEN 0 128 127.0.0.1:2381 0.0.0.0:*
LISTEN 0 128 127.0.0.1:80 0.0.0.0:*
[root@master ~]# curl 127.0.0.1
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
[root@master ~]# kubectl port-forward --address 0.0.0.0 deployment/web 80
Forwarding from 0.0.0.0:80 -> 80
//允许所有IP访问80端口
[root@master ~]# curl 192.168.145.250
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
label
更新（增加、修改或删除）资源上的 label（标签）
label 必须以字母或数字开头，可以使用字母、数字、连字符、点和下划线，最长63个字符。
如果–overwrite 为 true，则可以覆盖已有的 label，否则尝试覆盖 label 将会报错。
如果指定了–resource-version，则更新将使用此资源版本，否则将使用现有的资源版本。
//更改标签
[root@master ~]# kubectl describe deployment/nginx
Name: nginx
Namespace: default
CreationTimestamp: Mon, 20 Dec 2021 22:20:38 +0800
Labels: app=nginx
Annotations: deployment.kubernetes.io/revision: 1
Selector: app=nginx
Replicas: 5 desired | 5 updated | 5 total | 5 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: app=nginx
Containers:
nginx:
Image: nginx
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Progressing True NewReplicaSetAvailable
Available True MinimumReplicasAvailable
OldReplicaSets: <none>
NewReplicaSet: nginx-6799fc88d8 (5/5 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 37m deployment-controller Scaled up replica set nginx-6799fc88d8 to 1
Normal ScalingReplicaSet 29m deployment-controller Scaled up replica set nginx-6799fc88d8 to 3
Normal ScalingReplicaSet 28m deployment-controller Scaled up replica set nginx-6799fc88d8 to 5
//追加标签
[root@master ~]# kubectl label deployment/nginx user=jing
deployment.apps/nginx labeled
[root@master ~]# kubectl describe deployment/nginx
Name: nginx
Namespace: default
CreationTimestamp: Mon, 20 Dec 2021 22:20:38 +0800
Labels: app=nginx
user=jing
api-resources
在服务器上打印支持的 API 资源
//查看所有资源
[root@master ~]# kubectl api-resources
NAME SHORTNAMES APIVERSION NAMESPACED KIND
bindings v1 true Binding
componentstatuses cs v1 false ComponentStatus
configmaps cm v1 true ConfigMap
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api-versions
在服务器上以’组/版本’的形式打印支持的api版本
[root@master ~]# kubectl api-versions
admissionregistration.k8s.io/v1
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
logs
查看日志
输出pod或指定资源中容器的日志。如果pod中只有一个容器，则容器名是可选的
// 查看nginx的日志
[root@master ~]# kubectl logs deployment/nginx
Found 5 pods, using pod/nginx-6799fc88d8-dwrsh
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2021/12/20 14:14:43 [notice] 1#1: using the "epoll" event method
2021/12/20 14:14:43 [notice] 1#1: nginx/1.21.4
2021/12/20 14:14:43 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6)
2021/12/20 14:14:43 [notice] 1#1: OS: Linux 4.18.0-257.el8.x86_64
2021/12/20 14:14:43 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2021/12/20 14:14:43 [notice] 1#1: start worker processes
2021/12/20 14:14:43 [notice] 1#1: start worker process 32
2021/12/20 14:14:43 [notice] 1#1: start worker process 33
attach
附加在一个容器里
连接到一个正在运行的容器
//获取正在运行中的pod nginx的输出，默认连接到pod中的第一个容器
[root@master ~]# kubectl attach nginx
Defaulting container name to nginx.
Use 'kubectl describe pod/nginx -n default' to see all of the containers in this pod.
If you don't see a command prompt, try pressing enter.
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exec
进到容器内执行一个命令
//默认在pod/nginx的第一个容器中运行date并打印输出
[root@master ~]# kubectl exec deployment/nginx date
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
Mon Dec 20 14:38:25 UTC 2021
port-forward
转发一个或多个端口到pod里面去
//将容器中的80端口随即映射到本机的端口
[root@master ~]# kubectl port-forward nginx-6799fc88d8-5tsjt :80
Forwarding from 127.0.0.1:46459 -> 80
Forwarding from [::1]:46459 -> 80
[root@master ~]# curl 127.0.0.1:46459
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
[root@master ~]#
cp
拷贝文件或目录到容器中，或者从容器内向外拷贝
//将本地的anaconda-ks.cfg文件传输到pod/nginx的/tmp目录下
[root@master ~]# kubectl cp anaconda-ks.cfg nginx-6799fc88d8-5tsjt:/tmp
[root@master ~]# kubectl exec pod/nginx-6799fc88d8-5tsjt -- ls -l /tmp
total 4
-rw------- 1 root root 1252 Dec 20 14:48 anaconda-ks.cfg
快速部署一个网站
在Kubernetes部署应用流程：
- 制作镜
- dockerfile
- 使用控制器部署镜像（下面三，任选一个）
- Delopment
- StatefulSet
- DaemonSet
- 对外暴露应用
- 创建一个service让它能够访问
- 日志、监控
- 日常运维
基本资源概念
- pod：k8s最小部署单元，一组容器的集合
- Deployment：最常见的控制器，用于更高级别部署和管理pod
- Serivce：为一组pod提供负载均衡，对外提供统一访问入口
- Label：标签，附加到某个资源上，用于关联对象、查询和筛选
- Namespaces：命名空间，将对象逻辑上隔离，也利于权限控制
命名空间
命名空间（Namespace）：Kubernetes将资源对象逻辑上隔离，从而形成多个虚拟集群。 应用场景：
- 根据不同团队划分命名空间
- 根据项目划分命名空间
kubectl get namespace
- default:默认命名空间
- kube-system: K8s系统方面的命名空间.
- kube-public: 公开的命名空间，谁都可以访问
- kube-node-lease: K8s内部命名空间
两种方法指定资源命名空间：
- 命令行加-n -yaml资源元数据里指定namespace字段
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