CustomResourceDefinition简介：
在 Kubernetes 中所有都可视为资源，Kubernetes 1.7 之后减少了对 CRD 自定义资源二次开发能力来扩大 Kubernetes API，通过 CRD 咱们能够向 Kubernetes API 中减少新资源类型，而不须要批改 Kubernetes 源码来创立自定义的 API server，该性能大大提高了 Kubernetes 的扩大能力。
当你创立一个新的CustomResourceDefinition (CRD)时，Kubernetes API服务器将为你指定的每个版本创立一个新的RESTful资源门路，咱们能够依据该api门路来创立一些咱们本人定义的类型资源。CRD能够是命名空间的，也能够是集群范畴的，由CRD的作用域(scpoe)字段中所指定的，与现有的内置对象一样，删除名称空间将删除该名称空间中的所有自定义对象。customresourcedefinition自身没有名称空间，所有名称空间都能够应用。
- 目前扩大Kubernetes API的罕用形式有3种:
- 应用CRD(CustomResourceDefinitions)自定义资源类型
- 开发自定义的APIServer并聚合至主API Server
- 及定制扩大API Server源码。这其中，CRD最为易用但限度颇多，自定义API Server更富于弹性但代码工作量偏大，而仅在必须增加新的外围类型能力确保专用的Kberneves集群性能失常，才应该定制零碎源码
- CRD-->CRT-->CR
其中CRD与CRT个别由开发或服务供应商提供
CRD只是定义一个类型Kind，但理论把kind运行起来CR须要有Controller来对资源进行管制，所有只有定义CRD定义没有并没有实际意义，当然也能够通过定义当初kind来运行，比方deployment 通过定义 RC来运行
配置标准
apiVersion: apiextensions.k8s.io/v1 #API群组和版本kind: CustomResourceDefinition #资源类别metadata: -name <string> #资源名称spec: conversion <object> #定义不同版本间的格局转换形式 strategy <string># 不同版本间的自定义资源转换策略，有None和webhook两种取值 webhook <0bject>#如何调用用于进行格局转换的webhook group <string>#资源所属的API群组 names <object># 自定义资源的类型，即该CRD创立资源标准时应用的kind categories <[]string>#资源所属的类别编目，例如"kubectl get all"中的all kind <string> #kind名称,必选字段 listKind <string> #资源列表名称，默认为"`kind`List" plural <string> #复数，用于API门路`/apis/<group>/<version>/. . ./<plural>' shortNames <[string>#该资源的kind的缩写格局 singular <string>#资源kind的复数模式，必须应用全小写字母，默认为小写的kind名称 preserveUnknownFields <boolean> #预留的非知名字段，kind等都是出名的预留字段 scope <string> #作用域，可用值为Cluster和Namespaced versions <[]object>#版本号定义 additionalPrinterColumns <[]0bject> #须要返回的额定信息 name <string> #形如vM[alphaN|betaN]格局的版本名称，例如v1或vlalpha2等 schema <object> #该资源的数据格式(schema)定义，必选字段 openAPIV3Schema <object> #用于校验字段的schema对象，格局请参考相干手册 served <boolean> #是否容许通过RESTful API调度该版本，必选字段 storage <boolean> #将自定义资源存储于etcd中时是不是应用该版本 subresources <0bject>#子资源定义 scale <0bject># 启用scale子资源，通过autoscaling/v1.Scale发送负荷 status <map[string]># 启用status子资源，为资源生成/status端点- 能够查看之前部署Calico创立的自定义CRD
[root@k8s-master ~]# kubectl api-resources #查看所有资源类型NAME SHORTNAMES APIGROUP NAMESPACED KIND... bgpconfigurations crd.projectcalico.org false BGPConfigurationbgppeers crd.projectcalico.org false BGPPeerblockaffinities crd.projectcalico.org false BlockAffinityclusterinformations crd.projectcalico.org false ClusterInformationfelixconfigurations crd.projectcalico.org false FelixConfigurationglobalnetworkpolicies crd.projectcalico.org false GlobalNetworkPolicyglobalnetworksets crd.projectcalico.org false GlobalNetworkSethostendpoints crd.projectcalico.org false HostEndpointipamblocks crd.projectcalico.org false IPAMBlockipamconfigs crd.projectcalico.org false IPAMConfigipamhandles crd.projectcalico.org false IPAMHandleippools crd.projectcalico.org false IPPoolkubecontrollersconfigurations crd.projectcalico.org false KubeControllersConfigurationnetworkpolicies crd.projectcalico.org true NetworkPolicynetworksets crd.projectcalico.org true NetworkSet查看calico的yaml文件能够看到外面很多CRD的定义
[root@k8s-master plugin]# vim calico.yaml ...---apiVersion: apiextensions.k8s.io/v1kind: CustomResourceDefinitionmetadata:name: ippools.crd.projectcalico.orgspec:.........[root@k8s-master plugin]# kubectl get CustomResourceDefinitionNAME CREATED ATbgpconfigurations.crd.projectcalico.org 2021-08-29T14:33:24Zbgppeers.crd.projectcalico.org 2021-08-29T14:33:24Zblockaffinities.crd.projectcalico.org 2021-08-29T14:33:24Zclusterinformations.crd.projectcalico.org 2021-08-29T14:33:24Zfelixconfigurations.crd.projectcalico.org 2021-08-29T14:33:24Zglobalnetworkpolicies.crd.projectcalico.org 2021-08-29T14:33:24Zglobalnetworksets.crd.projectcalico.org 2021-08-29T14:33:24Zhostendpoints.crd.projectcalico.org 2021-08-29T14:33:24Zipamblocks.crd.projectcalico.org 2021-08-29T14:33:24Zipamconfigs.crd.projectcalico.org 2021-08-29T14:33:24Zipamhandles.crd.projectcalico.org 2021-08-29T14:33:24Zippools.crd.projectcalico.org 2021-08-29T14:33:24Zkubecontrollersconfigurations.crd.projectcalico.org 2021-08-29T14:33:24Znetworkpolicies.crd.projectcalico.org 2021-08-29T14:33:24Znetworksets.crd.projectcalico.org 2021-08-29T14:33:25Z示例1: 创立自定义CRD
[root@k8s-master crd]# cat crd-v1-user.yaml apiVersion: apiextensions.k8s.io/v1kind: CustomResourceDefinitionmetadata:name: users.auth.ilinux.iospec:group: auth.ilinux.ionames: kind: User plural: users singular: user shortNames: - uscope: Namespaced #名称空间级别versions:- served: true storage: true name: v1alpha1 #版本号 schema: openAPIV3Schema: type: object #对字段做限度 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-resourcesNAME SHORTNAMES APIGROUP NAMESPACED KINDbindings true Binding...users u auth.ilinux.io true User发明自定义CRD类型
[root@k8s-master crd]# cat user-cr-demo.yaml apiVersion: auth.ilinux.io/v1alpha1kind: Usermetadata:name: adminnamespace: defaultspec:userID: 1email: test@test.comgroups:- superusers- adminstratorspassword: 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 UserNAME AGEadmin 14s[root@k8s-master ~]# kubectl describe User adminName: adminNamespace: defaultLabels: <none>Annotations: <none>API Version: auth.ilinux.io/v1alpha1Kind: UserMetadata:Creation Timestamp: 2021-09-10T14:51:53ZGeneration: 1Managed 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: 2021-09-10T14:51:53ZResource Version: 2583010Self Link: /apis/auth.ilinux.io/v1alpha1/namespaces/default/users/adminUID: 5af89454-e067-4f30-83b7-cc2ad82e3526Spec:Email: test@test.comGroups: superusers adminstratorsPassword: ikubernetes.ioUser ID: 1Events: <none>- 以上定义的kind资源 没Controller并不能运行成理论对象，Controller的开发须要开发来实现
示例2: etcd Operator 部署 (该我的项目已不在保护)
Operator 我的项目地址:
https://github.com/operator-f...
https://github.com/coreos/etc...
https://github.com/coreos/etc...先装置RBAC 再装置etcd operator 再部署创立etcd集群
[root@k8s-master etcd-operator]# example/rbac/create_role.shCreating role with ROLE_NAME=etcd-operator, NAMESPACE=defaultWarning: rbac.authorization.k8s.io/v1beta1 ClusterRole is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRoleclusterrole.rbac.authorization.k8s.io/etcd-operator createdCreating role binding with ROLE_NAME=etcd-operator, ROLE_BINDING_NAME=etcd-operator, NAMESPACE=defaultWarning: rbac.authorization.k8s.io/v1beta1 ClusterRoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRoleBindingclusterrolebinding.rbac.authorization.k8s.io/etcd-operator created[root@k8s-master etcd-operator]# kubectl create -f example/deployment.yamlerror: unable to recognize "example/deployment.yaml": no matches for kind "Deployment" in version "extensions/v1beta1"#deployment版本太老批改example/deployment.yaml[root@k8s-master etcd-operator]# cat example/deployment.yamlapiVersion: apps/v1 #版本kind: Deploymentmetadata:name: etcd-operatorspec:replicas: 1selector: #增加字段 matchLabels: name: etcd-operatortemplate: 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.yamldeployment.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
- 部署创立etcd集群
[root@k8s-master etcd-operator]# cat example/example-etcd-cluster.yamlapiVersion: "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: clusterwidespec:size: 3 #集群数理version: "3.2.13"[root@k8s-master etcd-operator]# kubectl apply -f example/example-etcd-cluster.yamletcdcluster.etcd.database.coreos.com/example-etcd-cluster created[root@k8s-master etcd-operator]# kubectl get pod -o wideNAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESetcd-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>前面在加一个SVC就能够应用了