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kubernetes?k8s?CRD自定義資源學(xué)習(xí)筆記

更新時間：2022年05月26日 08:51:02 作者：bigyong

這篇文章主要介紹了kubernetes?k8s?CRD自定義資源學(xué)習(xí)筆記，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進步，早日升職加薪

CustomResourceDefinition簡介：

在 Kubernetes 中一切都可視為資源，Kubernetes 1.7 之后增加了對 CRD 自定義資源二次開發(fā)能力來擴展 Kubernetes API，通過 CRD 我們可以向 Kubernetes API 中增加新資源類型，而不需要修改 Kubernetes 源碼來創(chuàng)建自定義的 API server，該功能大大提高了 Kubernetes 的擴展能力。

當你創(chuàng)建一個新的CustomResourceDefinition (CRD)時，Kubernetes API服務(wù)器將為你指定的每個版本創(chuàng)建一個新的RESTful資源路徑，我們可以根據(jù)該api路徑來創(chuàng)建一些我們自己定義的類型資源。CRD可以是命名空間的，也可以是集群范圍的，由CRD的作用域(scpoe)字段中所指定的，與現(xiàn)有的內(nèi)置對象一樣，刪除名稱空間將刪除該名稱空間中的所有自定義對象。customresourcedefinition本身沒有名稱空間，所有名稱空間都可以使用。

目前擴展Kubernetes API的常用方式有3種:

使用CRD(CustomResourceDefinitions)自定義資源類型
開發(fā)自定義的APIServer并聚合至主API Server
及定制擴展API Server源碼。這其中，CRD最為易用但限制頗多，自定義API Server更富于彈性但代碼工作量偏大，而僅在必須添加新的核心類型才能確保專用的Kberneves集群功能正常，才應(yīng)該定制系統(tǒng)源碼

CRD-->CRT-->CR

其中CRD與CRT一般由開發(fā)或服務(wù)供應(yīng)商提供
CRD只是定義一個類型Kind，但實際把kind運行起來CR需要有Controller來對資源進行控制，所有只有定義CRD定義沒有并沒有實際意義，當然也可以通過定義現(xiàn)在kind來運行，比如deployment 通過定義 RC來運行

配置規(guī)范

apiVersion: apiextensions.k8s.io/v1 #API群組和版本
kind: CustomResourceDefinition #資源類別
metadata:
  -name <string> #資源名稱
spec:
  conversion <object> #定義不同版本間的格式轉(zhuǎn)換方式
    strategy <string># 不同版本間的自定義資源轉(zhuǎn)換策略，有None和webhook兩種取值
    webhook <0bject>#如何調(diào)用用于進行格式轉(zhuǎn)換的webhook
  group <string>#資源所屬的API群組
  names <object># 自定義資源的類型，即該CRD創(chuàng)建資源規(guī)范時使用的kind
    categories <[]string>#資源所屬的類別編目，例如"kubectl get all"中的all
    kind <string> #kind名稱,必選字段
    listKind <string> #資源列表名稱，默認為"`kind`List"
    plural <string>  #復(fù)數(shù)，用于API路徑`/apis/<group>/<version>/. . ./<plural>'
    shortNames <[string>#該資源的kind的縮寫格式
    singular <string>#資源kind的單數(shù)形式，必須使用全小寫字母，默認為小寫的kind名稱
  preserveUnknownFields <boolean> #預(yù)留的非知名字段，kind等都是知名的預(yù)留字段
  scope <string> #作用域，可用值為Cluster和Namespaced
  versions <[]object>#版本號定義
    additionalPrinterColumns <[]0bject> #需要返回的額外信息
    name <string>  #形如vM[alphaN|betaN]格式的版本名稱，例如v1或vlalpha2等
    schema <object> #該資源的數(shù)據(jù)格式(schema)定義，必選字段
      openAPIV3Schema <object> #用于校驗字段的schema對象，格式請參考相關(guān)手冊
    served <boolean> #是否允許通過RESTful API調(diào)度該版本，必選字段
    storage <boolean> #將自定義資源存儲于etcd中時是不是使用該版本
    subresources <0bject>#子資源定義
      scale <0bject># 啟用scale子資源，通過autoscaling/v1.Scale發(fā)送負荷
      status <map[string]># 啟用status子資源，為資源生成/status端點

可以查看之前部署Calico創(chuàng)建的自定義CRD

[root@k8s-master ~]# kubectl api-resources      #查看所有資源類型
NAME                              SHORTNAMES   APIGROUP                       NAMESPACED   KIND
...  
bgpconfigurations                              crd.projectcalico.org          false        BGPConfiguration
bgppeers                                       crd.projectcalico.org          false        BGPPeer
blockaffinities                                crd.projectcalico.org          false        BlockAffinity
clusterinformations                            crd.projectcalico.org          false        ClusterInformation
felixconfigurations                            crd.projectcalico.org          false        FelixConfiguration
globalnetworkpolicies                          crd.projectcalico.org          false        GlobalNetworkPolicy
globalnetworksets                              crd.projectcalico.org          false        GlobalNetworkSet
hostendpoints                                  crd.projectcalico.org          false        HostEndpoint
ipamblocks                                     crd.projectcalico.org          false        IPAMBlock
ipamconfigs                                    crd.projectcalico.org          false        IPAMConfig
ipamhandles                                    crd.projectcalico.org          false        IPAMHandle
ippools                                        crd.projectcalico.org          false        IPPool
kubecontrollersconfigurations                  crd.projectcalico.org          false        KubeControllersConfiguration
networkpolicies                                crd.projectcalico.org          true         NetworkPolicy
networksets                                    crd.projectcalico.org          true         NetworkSet

查看calico的yaml文件可以看到里面很多CRD的定義

[root@k8s-master plugin]# vim calico.yaml   
...
---
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: ippools.crd.projectcalico.org
spec:
......
...
[root@k8s-master plugin]# kubectl get CustomResourceDefinition
NAME                                                  CREATED AT
bgpconfigurations.crd.projectcalico.org               2021-08-29T14:33:24Z
bgppeers.crd.projectcalico.org                        2021-08-29T14:33:24Z
blockaffinities.crd.projectcalico.org                 2021-08-29T14:33:24Z
clusterinformations.crd.projectcalico.org             2021-08-29T14:33:24Z
felixconfigurations.crd.projectcalico.org             2021-08-29T14:33:24Z
globalnetworkpolicies.crd.projectcalico.org           2021-08-29T14:33:24Z
globalnetworksets.crd.projectcalico.org               2021-08-29T14:33:24Z
hostendpoints.crd.projectcalico.org                   2021-08-29T14:33:24Z
ipamblocks.crd.projectcalico.org                      2021-08-29T14:33:24Z
ipamconfigs.crd.projectcalico.org                     2021-08-29T14:33:24Z
ipamhandles.crd.projectcalico.org                     2021-08-29T14:33:24Z
ippools.crd.projectcalico.org                         2021-08-29T14:33:24Z
kubecontrollersconfigurations.crd.projectcalico.org   2021-08-29T14:33:24Z
networkpolicies.crd.projectcalico.org                 2021-08-29T14:33:24Z
networksets.crd.projectcalico.org                     2021-08-29T14:33:25Z

示例1: 創(chuàng)建自定義CRD

[root@k8s-master crd]# cat crd-v1-user.yaml 
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: users.auth.ilinux.io
spec:
  group: auth.ilinux.io
  names:
    kind: User
    plural: users
    singular: user
    shortNames:
    - u
  scope: Namespaced  #名稱空間級別
  versions:
  - served: true
    storage: true
    name: v1alpha1  #版本號
    schema:
      openAPIV3Schema:
        type: object    #對字段做限制 
        properties:
          spec:
            type: object
            properties:
              userID:
                type: integer  #整形
                minimum: 1
                maximum: 65535
              groups :
                type: array   #列表
                items:
                  type: string
              email:
                type: string
              password:
                type: string
                format: password
            required: ["userID","groups"]
[root@k8s-master crd]# kubectl apply -f crd-v1-user.yaml 
[root@k8s-master crd]# kubectl api-resources
NAME                              SHORTNAMES   APIGROUP                       NAMESPACED   KIND
bindings                                                                      true         Binding
...
users                             u            auth.ilinux.io                 true         User

創(chuàng)造自定義CRD類型

[root@k8s-master crd]# cat user-cr-demo.yaml 
apiVersion: auth.ilinux.io/v1alpha1
kind: User
metadata:
  name: admin
  namespace: default
spec:
  userID: 1
  email: test@test.com
  groups:
  - superusers
  - adminstrators
  password: ikubernetes.io
[root@k8s-master crd]# kubectl apply -f user-cr-demo.yaml 
user.auth.ilinux.io/admin created
[root@k8s-master crd]# kubectl get User
NAME    AGE
admin   14s
[root@k8s-master ~]# kubectl describe User admin
Name:         admin
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  auth.ilinux.io/v1alpha1
Kind:         User
Metadata:
  Creation Timestamp:  2021-09-10T14:51:53Z
  Generation:          1
  Managed Fields:
    API Version:  auth.ilinux.io/v1alpha1
    Fields Type:  FieldsV1
    fieldsV1:
      f:metadata:
        f:annotations:
          .:
          f:kubectl.kubernetes.io/last-applied-configuration:
      f:spec:
        .:
        f:email:
        f:groups:
        f:password:
        f:userID:
    Manager:         kubectl-client-side-apply
    Operation:       Update
    Time:            2021-09-10T14:51:53Z
  Resource Version:  2583010
  Self Link:         /apis/auth.ilinux.io/v1alpha1/namespaces/default/users/admin
  UID:               5af89454-e067-4f30-83b7-cc2ad82e3526
Spec:
  Email:  test@test.com
  Groups:
    superusers
    adminstrators
  Password:  ikubernetes.io
  User ID:   1
Events:      <none>

以上定義的kind資源沒Controller并不能運行成實際對象，Controller的開發(fā)需要開發(fā)來完成

示例2: etcd Operator 部署 (該項目已不在維護)

Operator 項目地址:

https://github.com/coreos/etcd-operator/blob/master/doc/user/install_guide.md

https://github.com/coreos/etcd-operator

https://github.com/operator-framework/awesome-operators

先安裝RBAC 再安裝etcd operator 再部署創(chuàng)建etcd集群

[root@k8s-master etcd-operator]# example/rbac/create_role.sh
Creating role with ROLE_NAME=etcd-operator, NAMESPACE=default
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRole is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRole
clusterrole.rbac.authorization.k8s.io/etcd-operator created
Creating role binding with ROLE_NAME=etcd-operator, ROLE_BINDING_NAME=etcd-operator, NAMESPACE=default
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRoleBinding
clusterrolebinding.rbac.authorization.k8s.io/etcd-operator created
[root@k8s-master etcd-operator]# kubectl create -f example/deployment.yaml
error: unable to recognize "example/deployment.yaml": no matches for kind "Deployment" in version "extensions/v1beta1"
#deployment版本太老修改example/deployment.yaml
[root@k8s-master etcd-operator]# cat example/deployment.yaml
apiVersion: apps/v1  #版本
kind: Deployment
metadata:
  name: etcd-operator
spec:
  replicas: 1
  selector:   #添加字段
    matchLabels:
      name: etcd-operator
  template:
    metadata:
      labels:
        name: etcd-operator
    spec:
      containers:
      - name: etcd-operator
        image: quay.io/coreos/etcd-operator:v0.9.4
        command:
        - etcd-operator
        # Uncomment to act for resources in all namespaces. More information in doc/user/clusterwide.md
        #- -cluster-wide
        env:
        - name: MY_POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: MY_POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
[root@k8s-master etcd-operator]# kubectl create -f example/deployment.yaml
deployment.apps/etcd-operator created
[root@k8s-master etcd-operator]# 
[root@k8s-master etcd-operator]# kubectl api-resources
...
etcdclusters                      etcd         etcd.database.coreos.com       true         EtcdCluster

部署創(chuàng)建etcd集群

[root@k8s-master etcd-operator]# cat example/example-etcd-cluster.yaml
apiVersion: "etcd.database.coreos.com/v1beta2"
kind: "EtcdCluster"
metadata:
  name: "example-etcd-cluster"
  ## Adding this annotation make this cluster managed by clusterwide operators
  ## namespaced operators ignore it
  # annotations:
  #   etcd.database.coreos.com/scope: clusterwide
spec:
  size: 3  #集群數(shù)理
  version: "3.2.13"
[root@k8s-master etcd-operator]# kubectl apply -f  example/example-etcd-cluster.yaml
etcdcluster.etcd.database.coreos.com/example-etcd-cluster created
[root@k8s-master etcd-operator]# kubectl get pod -o wide
NAME                              READY   STATUS    RESTARTS   AGE    IP              NODE        NOMINATED NODE   READINESS GATES
etcd-operator-646cbffdb6-brbn6    1/1     Running   0          12m    192.168.51.58   k8s-node3   <none>           <none>
example-etcd-cluster-nc8pdgjrjr   1/1     Running   0          3m3s   192.168.51.59   k8s-node3   <none>           <none>
- 后面在加一個SVC就可以使用了

以上就是kubernetes k8s CRD自定義資源學(xué)習(xí)筆記的詳細內(nèi)容，更多關(guān)于kubernetes(k8s) CRD的資料請關(guān)注腳本之家其它相關(guān)文章！

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