一步步学习k8s(二)

一步步学习k8s（二）

一、管理K8S核心资源的三种基本方法

pod、pod控制器、service、ingress

• 1、陈述式管理方法：主要依赖命令行CLI工具进行管理
• 2、声明是管理方法：主要依赖统一资源配置清单（manifest）进行管理
• 3、GUI式管理方法：主要依赖图形化操作界面（web界面）进行管理

Kubectl命令行工具使用详解

1.1、陈述式管理方法

1.1.1、管理空间名称资源

1.1.1.1、查看名称空间

主要用get查看基本信息

Usage:  kubectl get resource [-o wide|json|yaml] [-n namespace]
Man:    获取资源的相关信息，-n 指定名称空间，-o 指定输出格式
        resource可以是具体资源名称，如pod nginx-xxx；也可以是资源类型，如pod；或者all(仅展示几种核心资源，并不完整)
        -A, --all-namespace 表示显示所有名称空间

还可用describe来详细查看

Usage: kubectl describe (-f FILENAME | TYPE [NAME_PREFIX | -l label] | TYPE/NAME) [-n namespace]
Man:   描述某个资源信息

登录任一运算节点,我这里选择10.4.7.21

[root@hdss7-21 ~]# kubectl get namespace		# 简写是：kubectl get ns
NAME              STATUS   AGE
default           Active   6d17h
kube-node-lease   Active   6d17h
kube-public       Active   6d17h
kube-system       Active   6d17h

1.1.1.2、查看名称空间内的资源

查看名称空间为default的全部资源

[root@hdss7-21 ~]# kubectl get all [-n default]
NAME                 READY   STATUS    RESTARTS   AGE
pod/nginx-ds-t8mwg   1/1     Running   2          44h
pod/nginx-ds-tjkt2   1/1     Running   2          44h

NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   192.168.0.1           443/TCP   6d17h

NAME                      DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
daemonset.apps/nginx-ds   2         2         2       2            2                     44h

1.1.1.3、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   12s
default           Active   6d17h
kube-node-lease   Active   6d17h
kube-public       Active   6d17h
kube-system       Active   6d17h

1.1.1.4、删除名称空间

[root@hdss7-21 ~]# kubectl delete ns app
namespace "app" deleted

1.1.2、管理Deployment

1.1.2.1、创建deployment和查看

[root@hdss7-21 ~]# kubectl create deployment nginx-dp --image=harbor.od.com/public/nginx:v1.7.9 -n kube-public
deployment.apps/nginx-dp created
[root@hdss7-21 ~]# kubectl get deploy -n kube-public
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
nginx-dp   1/1     1            1           69s
[root@hdss7-21 ~]# kubectl get pods -n kube-public
NAME                        READY   STATUS    RESTARTS   AGE
nginx-dp-5dfc689474-mxtnz   1/1     Running   0          2m46s
[root@hdss7-21 ~]# kubectl get pods -n kube-public -o wide
NAME                        READY   STATUS    RESTARTS   AGE    IP           NODE                NOMINATED NODE   READINESS GATES
nginx-dp-5dfc689474-mxtnz   1/1     Running   0          4m1s   172.7.21.3   hdss7-21.host.com              

1.1.2.2、详细查看

[root@hdss7-21 ~]# kubectl describe deployment nginx-dp -n kube-public
Name:                   nginx-dp
Namespace:              kube-public
CreationTimestamp:      Wed, 21 Apr 2021 21:10:41 +0800
Labels:                 app=nginx-dp
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=nginx-dp
Replicas:               1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx-dp
  Containers:
   nginx:
    Image:        harbor.od.com/public/nginx:v1.7.9
    Port:         
    Host Port:    
    Environment:  
    Mounts:       
  Volumes:        
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  
NewReplicaSet:   nginx-dp-5dfc689474 (1/1 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  14m   deployment-controller  Scaled up replica set nginx-dp-5dfc689474 to 1

1.1.2.3、进入pod资源

[root@hdss7-21 ~]# kubectl exec -it nginx-dp-5dfc689474-mxtnz /bin/bash -n kube-public
root@nginx-dp-5dfc689474-mxtnz:/# ip a
1: lo:  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:  mtu 1500 qdisc noqueue state UP 
    link/ether 02:42:ac:07:15:03 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

也可以使用docker exec -it 进入容器

1.1.2.4、删除pod(重启)

等于是一部重启的操作，因为删除之后再查看，pod的名字变了

[root@hdss7-21 ~]# kubectl delete pod nginx-dp-5dfc689474-mxtnz -n kube-public
pod "nginx-dp-5dfc689474-mxtnz" deleted
[root@hdss7-21 ~]# 
[root@hdss7-21 ~]# kubectl get pods -n kube-public
NAME                        READY   STATUS    RESTARTS   AGE
nginx-dp-5dfc689474-vcqw5   1/1     Running   0          3s

1.1.2.5、删除Depolyment

[root@hdss7-21 ~]# kubectl delete deployment nginx-dp -n kube-public
deployment.extensions "nginx-dp" deleted
[root@hdss7-21 ~]# kubectl get all -n kube-public

No resources found.

1.1.3、管理Service资源

1.1.3.1、创建service

先创建pod控制器

[root@hdss7-21 ~]# kubectl create deployment nginx-dp --image=harbor.od.com/public/nginx:v1.7.9 -n kube-public
deployment.apps/nginx-dp created
[root@hdss7-21 ~]# 
[root@hdss7-21 ~]# kubectl get all -n kube-public
NAME                            READY   STATUS    RESTARTS   AGE
pod/nginx-dp-5dfc689474-twtg5   1/1     Running   0          24s
NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-dp   1/1     1            1           24s
NAME                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-dp-5dfc689474   1         1         1       24s

再创建service

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

1.1.3.2、查看service

[root@hdss7-21 ~]# kubectl get all -n kube-public
NAME                            READY   STATUS    RESTARTS   AGE
pod/nginx-dp-5dfc689474-twtg5   1/1     Running   0          5m3s

NAME               TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
service/nginx-dp   ClusterIP   192.168.44.93           80/TCP    59s

NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-dp   1/1     1            1           5m3s

NAME                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-dp-5dfc689474   1         1         1       5m3s

1.1.3.3、查看端口代理

[root@hdss7-22 ~]# 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  192.168.44.93:80 nq
  -> 172.7.21.3:80                Masq    1      0          0

1.1.3.4、扩容service

[root@hdss7-21 ~]# kubectl scale deployment nginx-dp --replicas=2 -n kube-public
deployment.extensions/nginx-dp scaled
[root@hdss7-21 ~]# 
[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  192.168.44.93:80 nq
  -> 172.7.21.3:80                Masq    1      0          0
  -> 172.7.22.3:80                Masq    1      0          0

1.1.4、kubectl用法总结

• Kubernetes集群管理集群资源的唯一入口是通过相应的方法调用apiserver的接口
• kubectl是官方的CLI命令行工具，用于与apiserver进行通信，将用户在命令行输入的命令，组织转化为aoiserver能识别的信息，进而实现管理k8s各种资源的一种有效的途径。
• kubectl命令大全
  • kubectl --help
  • http://docs.kubernetes.org.cn
• 陈述式管理能满足90%以上的资源管理需求，但缺点也很明显：
  • 命令冗长、复杂、难记
  • 特定场景下，难以实现管理需求
  • 对资源的增、删、查容易，但改很麻烦

1.2、声明式管理方法

声明式资源管理方法依赖于—资源配置清单（yaml/json）

1.2.1、查看资源配置清单的方法

1.2.1.1、查看pods

root@hdss7-21 ~]# kubectl get pods -n kube-public
NAME                      READY   STATUS    RESTARTS   AGE
nginx-dp-5dfc689474-twtg5 1/1     Running   1          23h

[root@hdss7-21 ~]# kubectl get pods nginx-dp-5dfc689474-twtg5 -o yaml -n kube-public
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2021-04-21T14:01:09Z"
  generateName: nginx-dp-5dfc689474-
  labels:
    app: nginx-dp
    pod-template-hash: 5dfc689474
  name: nginx-dp-5dfc689474-twtg5
  namespace: kube-public
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: ReplicaSet
    name: nginx-dp-5dfc689474
    uid: fd61affd-bb07-494b-bd80-cca2830a53a0
  resourceVersion: "51413"
  selfLink: /api/v1/namespaces/kube-public/pods/nginx-dp-5dfc689474-twtg5
  uid: 4c1b4cb9-44c8-4772-b448-16ae4073ac9c
spec:
  containers:
  - image: harbor.od.com/public/nginx:v1.7.9
    imagePullPolicy: IfNotPresent
    name: nginx
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: default-token-rxkkz
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  nodeName: hdss7-21.host.com
  priority: 0
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {}
  serviceAccount: default
  serviceAccountName: default
  terminationGracePeriodSeconds: 30
  tolerations:
  - effect: NoExecute
    key: node.kubernetes.io/not-ready
    operator: Exists
    tolerationSeconds: 300
  - effect: NoExecute
    key: node.kubernetes.io/unreachable
    operator: Exists
    tolerationSeconds: 300
  volumes:
  - name: default-token-rxkkz
    secret:
      defaultMode: 420
      secretName: default-token-rxkkz
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2021-04-21T14:01:09Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2021-04-22T13:14:49Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2021-04-22T13:14:49Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2021-04-21T14:01:09Z"
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: docker://4f8cbfdc4c1fc3c8ba8b196f76a3f0c5ec269ba069344849f3b5d3a29f9ca826
    image: harbor.od.com/public/nginx:v1.7.9
    imageID: docker-pullable://harbor.od.com/public/nginx@sha256:b1f5935eb2e9e2ae89c0b3e2e148c19068d91ca502e857052f14db230443e4c2
    lastState:
      terminated:
        containerID: docker://3b965ed0b5ce249c19cf0c543ae52578f4224d8e12360267384dcfdefe730b76
        exitCode: 255
        finishedAt: "2021-04-22T13:14:41Z"
        reason: Error
        startedAt: "2021-04-21T14:01:10Z"
    name: nginx
    ready: true
    restartCount: 1
    state:
      running:
        startedAt: "2021-04-22T13:14:48Z"
  hostIP: 10.4.7.21
  phase: Running
  podIP: 172.7.21.2
  qosClass: BestEffort
  startTime: "2021-04-21T14:01:09Z"

1.2.1.2、查看serveice

[root@hdss7-22 ~]# kubectl get svc -n kube-public
NAME       TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
nginx-dp   ClusterIP   192.168.44.93           80/TCP    23h

[root@hdss7-22 ~]# kubectl get svc nginx-dp -o yaml -n kube-public
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2021-04-21T14:05:13Z"
  labels:
    app: nginx-dp
  name: nginx-dp
  namespace: kube-public
  resourceVersion: "48685"
  selfLink: /api/v1/namespaces/kube-public/services/nginx-dp
  uid: ed0dc55e-3cae-4c6c-85f1-cf4e5d902267
spec:
  clusterIP: 192.168.44.93
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx-dp
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

1.2.2、解释资源配置清单

[root@hdss7-22 ~]# kubectl explain service
KIND:     Service
VERSION:  v1

DESCRIPTION:
     Service is a named abstraction of software service (for example, mysql)
     consisting of local port (for example 3306) that the proxy listens on, and
     the selector that determines which pods will answer requests sent through
     the proxy.

FIELDS:
   apiVersion	
     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/api-conventions.md#resources

   kind	
     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/api-conventions.md#types-kinds

   metadata