【K8S运维知识汇总】第3天1：kubectl详解——陈述式资源管理方法(deployment资源、service资源)

查看名称空间：

[root@hdss7-21 ~]# kubectl get namespace　# 等同于kubectl get ns
NAME              STATUS   AGE
default           Active   3d22h
kube-node-lease   Active   3d22h
kube-public       Active   3d22h
kube-system       Active   3d22h

查看defalut名称空间下的所有资源：

[root@hdss7-21 ~]# kubectl get all -n default    # 等同于kubectl get all
NAME                 READY   STATUS    RESTARTS   AGE
pod/nginx-ds-pqszs   1/1     Running   0          2d12h
pod/nginx-ds-vnlx9   1/1     Running   0          2d12h


NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   192.168.0.1   <none>        443/TCP   3d23h

NAME                      DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
daemonset.apps/nginx-ds   0         0         0       0            0           <none>          2d12h

创建名称空间：

[root@hdss7-21 ~]# kubectl create namespace app
namespace/app created

[root@hdss7-21 ~]# kubectl get ns
NAME              STATUS   AGE
app               Active   45s
default           Active   3d23h
kube-node-lease   Active   3d23h
kube-public       Active   3d23h
kube-system       Active   3d23h

删除名称空间：

[root@hdss7-21 ~]# kubectl delete namespace app
namespace "app" deleted
[root@hdss7-21 ~]# kubectl get ns
NAME              STATUS   AGE
default           Active   3d23h
kube-node-lease   Active   3d23h
kube-public       Active   3d23h
kube-system       Active   3d23h

创建deployment资源：

# 在名称为kube-public的名称空间创建名称为nginx-db资源进行pod控制
[root@hdss7-21 ~]# kubectl create deployment nginx-dp --image=harbor.od.com/public/nginx:v1.7.9 -n kube-public
deployment.apps/nginx-db created

[root@hdss7-21 ~]# kubectl get deploy -n kube-public
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
nginx-db   0/1     1            0           2m28s

[root@hdss7-21 ~]# kubectl get pods -n kube-public
NAME                        READY   STATUS    RESTARTS   AGE
nginx-db-7b4dd9978d-8wzdl   0/1     Pending   0          2m52s

查看 kube-public名称空间下的Pod

[root@hdss7-21 ~]# kubectl get pods -n kube-public -o wide
NAME                        READY   STATUS    RESTARTS   AGE     IP       NODE     NOMINATED NODE   READINESS GATES
nginx-db-7b4dd9978d-8wzdl   0/1     Pending   0          8m15s   <none>   <none>   <none>           <none>

# 根据pod名称可以获得对应的容器，一般包含2个容器，分别是基础容器和业务容器

查看详细信息：

[root@hdss7-21 ~]# kubectl describe deployment nginx-db -n kube-public
Name:                   nginx-db
Namespace:              kube-public
CreationTimestamp:      Wed, 01 Jul 2020 10:58:43 +0800
Labels:                 app=nginx-db
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=nginx-db
Replicas:               1 desired | 1 updated | 1 total | 0 available | 1 unavailable
StrategyType:           RollingUpdate	# 发布策略：滚动升级
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx-db
  Containers:
   nginx:
    Image:        harbor.od.com/public/nginx:v1.7.9
    Port:         <none>
    Host Port:    <none>
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      False   MinimumReplicasUnavailable
  Progressing    False   ProgressDeadlineExceeded
OldReplicaSets:  <none>
NewReplicaSet:   nginx-db-7b4dd9978d (1/1 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  17m   deployment-controller  Scaled up replica set nginx-db-7b4dd9978d to 1

# kubectl发出的指令先找apiserver通信确认，apiserver再找scheduler确认,scheduler在最合适的节点通过kubelet来启动容器

进入pod资源

[root@hdss7-21 ~]# kubectl get pods -n kube-public
NAME                        READY   STATUS    RESTARTS   AGE
pod/nginx-dp-5dfc689474-fc6z9   1/1     Running       0          4s

# kubectl exec可以跨主机进入不同的pod
[root@hdss7-21 ~]# kubectl exec -it nginx-dp-5dfc689474-fc6z9 /bin/bash 
root@nginx-ds-pqszs:/# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue state UP 
    link/ether 02:42:ac:07:15:02 brd ff:ff:ff:ff:ff:ff
    inet 172.7.21.3/24 brd 172.7.21.255 scope global eth0
       valid_lft forever preferred_lft forever

删除pod资源：删除后，pod控制器会立即重启一个新的pod资源，是重启Pod的重要方法

[root@hdss7-21 ~]# kubectl delete pod nginx-db-7b4dd9978d-8wzdl -n kube-public 
pod "nginx-db-7b4dd9978d-8wzdl" deleted

# 强制删除
[root@hdss7-21 ~]# kubectl delete pod nginx-db-7b4dd9978d-8wzdl -n kube-public --force --grace-period=0

删除deployment资源

[root@hdss7-21 ~]# kubectl delete deployment nginx-db -n kube-public
deployment.extensions "nginx-db" deleted
[root@hdss7-21 ~]# kubectl get deployment -n kube-public
No resources found.
[root@hdss7-21 ~]# kubectl get pods -n kube-public
No resources found.
[root@hdss7-21 ~]# 

创建service资源

# 暴露80端口
[root@hdss7-21 ~]# kubectl expose deployment nginx-dp --port=80 -n kube-public
service/nginx-dp exposed


[root@hdss7-21 ~]# kubectl get all -n kube-public
NAME                            READY   STATUS    RESTARTS   AGE
pod/nginx-dp-5dfc689474-4dfsq   1/1     Running   0          44m
 


NAME               TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)   AGE
service/nginx-dp   ClusterIP   192.168.103.156   <none>        80/TCP    29m


NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-dp   2/2     2            2           44m

NAME                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-dp-5dfc689474   2         2         2       44m

查看端口是否可访问

# 当无法curl时，检查宿主机的内核中是否开启了ipv4转发功能
[root@hdss7-21 ~]# cat /proc/sys/net/ipv4/ip_forward
0
[root@hdss7-21 ~]# echo "1" >!$
echo "1" >/proc/sys/net/ipv4/ip_forward
[root@hdss7-21 ~]# cat /proc/sys/net/ipv4/ip_forward
1

[root@hdss7-21 ~]# curl 192.168.103.156 
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    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>
# 访问成功

# 查看lvs服务信息
[root@hdss7-21 ~]# ipvsadm -Ln 
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.0.1:443 nq
  -> 10.4.7.21:6443               Masq    1      0          0         
  -> 10.4.7.22:6443               Masq    1      0          0         
TCP  192.168.103.156:80 nq
  -> 172.7.22.2:80                Masq    1      0          0         

对deployment资源扩容：默认创建时只有一个pod资源

[root@hdss7-21 ~]# kubectl scale deployment nginx-dp --replicas=2 -n kube-public
deployment.extensions/nginx-dp scaled

# 查看扩容后的信息
[root@hdss7-21 ~]# ipvsadm -Ln 
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.0.1:443 nq
  -> 10.4.7.21:6443               Masq    1      0          0         
  -> 10.4.7.22:6443               Masq    1      0          0         
TCP  192.168.103.156:80 nq
  -> 172.7.22.2:80                Masq    1      0          0         
  -> 172.7.22.3:80                Masq    1      0          0    

查看svc详细信息

[root@hdss7-21 ~]# kubectl describe svc nginx-dp -n kube-public
Name:              nginx-dp	# service资源名称
Namespace:         kube-public
Labels:            app=nginx-dp
Annotations:       <none>
Selector:          app=nginx-dp		# pod标签名称，将service与pod关联起来
Type:              ClusterIP
IP:                192.168.103.156	# 该IP网段对集群内部使用
Port:              <unset>  80/TCP
TargetPort:        80/TCP
Endpoints:         172.7.21.2:80,172.7.22.2:80
Session Affinity:  None
Events:            <none>

总结