应该使用哪个 Group 和 Version?
日常使用的过程中我们经常碰到使用 YAML 定义 deployment等资源文件时， 经常弄不清楚资源的版本以及资源使用的组等信息， 如apiVersion: rbac.authorization.k8s.io/v1beta1 。
那么我们到底应该使用哪一个呢？哪一个才是正确的呢？如何检查Kubernetes集群支持哪些？其实我们使用kubectl工具就可以来解决我们的这些疑惑。
01.获取kubernetes支持API resource
我们使用如下指令获取当前版本的kubernetes支持哪些KIND， 属于哪个APIGROUP以及每个KIND支持哪些方法。
$ kubectl api-resources -o wide
NAME SHORTNAMES APIGROUP NAMESPACED KIND VERBS
selfsubjectaccessreviews authorization.k8s.io false SelfSubjectAccessReview [create]
selfsubjectrulesreviews authorization.k8s.io false SelfSubjectRulesReview [create]
subjectaccessreviews authorization.k8s.io false SubjectAccessReview [create]
horizontalpodautoscalers hpa autoscaling true HorizontalPodAutoscaler [create delete deletecollection get list patch update watch]
cronjobs cj batch true CronJob [create delete deletecollection get list patch update watch]
jobs batch true Job [create delete deletecollection get list patch update watch]
certificatesigningrequests csr certificates.k8s.io false CertificateSigningRequest [create delete deletecollection get list patch update watch]
leases coordination.k8s.io true Lease [create delete deletecollection get list patch update watch]
endpointslices discovery.k8s.io true EndpointSlice [create delete deletecollection get list patch update watch]
events ev events.k8s.io true Event [create delete deletecollection get list patch update watch]
ingresses ing extensions true Ingress [create delete deletecollection get list patch update watch]
ingressclasses networking.k8s.io false IngressClass [create delete deletecollection get list patch update watch]
ingresses ing networking.k8s.io true Ingress [create delete deletecollection get list patch update watch]
networkpolicies netpol networking.k8s.io true NetworkPolicy [create delete deletecollection get list patch update watch]
runtimeclasses node.k8s.io false RuntimeClass [create delete deletecollection get list patch update watch]
poddisruptionbudgets pdb policy true PodDisruptionBudget [create delete deletecollection get list patch update watch]
podsecuritypolicies psp policy false PodSecurityPolicy [create delete deletecollection get list patch update watch]
clusterrolebindings rbac.authorization.k8s.io false ClusterRoleBinding [create delete deletecollection get list patch update watch]
clusterroles rbac.authorization.k8s.io false ClusterRole [create delete deletecollection get list patch update watch]
rolebindings rbac.authorization.k8s.io true RoleBinding [create delete deletecollection get list patch update watch]
roles rbac.authorization.k8s.io true Role [create delete deletecollection get list patch update watch]
priorityclasses pc scheduling.k8s.io false PriorityClass [create delete deletecollection get list patch update watch]
csidrivers storage.k8s.io false CSIDriver [create delete deletecollection get list patch update watch]
..........
上面的命令输出了很多有用的信息：
- SHORTNAMES - 资源名称的简写，比如 deployments 简写就是 deploy，我们可以将这些快捷方式与kubectl一起使用
- APIGROUP - 我们可以查看官方文档以了解更多信息，但简而言之，您将在yaml文件中使用它像apiVersion：<APIGROUP>/v1
- KIND - 资源名称
- VERBS - 可用的方法，在您想要定义ClusterRole RBAC规则时也很有用，您还可以选择获取特定 API 组的 API 资源，例如：
$ kubectl api-resources --api-group apps -o wide
NAME SHORTNAMES APIGROUP NAMESPACED KIND VERBS
controllerrevisions apps true ControllerRevision [create delete deletecollection get list patch update watch]
daemonsets ds apps true DaemonSet [create delete deletecollection get list patch update watch]
deployments deploy apps true Deployment [create delete deletecollection get list patch update watch]
replicasets rs apps true ReplicaSet [create delete deletecollection get list patch update watch]
statefulsets sts apps true StatefulSet
对于上面的每种资源类型，我们都可以使用kubectl explain命令来获取有关的资源详细息：
$ kubectl explain configmap
DESCRIPTION:
ConfigMap holds configuration data for pods to consume.
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/api-conventions.md#resources
data <object>
Data contains the configuration data. Each key must consist of alphanumeric
characters, '-', '_' or '.'.
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/api-conventions.md#types-kinds
metadata <Object>
Standard object's metadata. More info:
https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata
kubectl explain命令非常有用，特别是在我们 不知道该如何编写YAML文件的时候，就可以使用改命令来帮助我们获得更多提示信息 。
需要注意的是explain命令可能会显示旧的group/version，我们可以通过--api-version参数显示设置它，比如： 请注意，explain可能会显示旧组/版本，但您可以使用–api-version显式设置它，例如：
$ kubectl explain replicaset --api-version apps/v1
02.获取支持的API VERSION
上节最后说到我们在查看资源的explain时可能并不知道集群支持的版本， 可以使用如下指令获取当前集群支持的 API 版本。
$ 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
batch/v1beta1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1
coordination.k8s.io/v1beta1
discovery.k8s.io/v1beta1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
networking.k8s.io/v1beta1
node.k8s.io/v1beta1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1
03.kubernetes REST path的构成
kubernetes 为了提供更好的扩展性所以才有了Apigroup的概念， 它是如何对外提供rest接口的呢？
目前使用的apigroup:
- 核心组， 对应的
ApiVersion: v1对应的rest path为/api/v1 - 其它的group的rest path为
/apis/$GROUP_NAME/$VERSION, 对应的apiVersion:$GROUP_NAME/$VERSION(e.g. apiVersion: batch/v1)
04.启用/关闭 apigroup
默认情况下有一些apigroup是启用状态， 可以在apiserver中指定--runtime-config参数启用/关闭apigroup。
- 关闭 batch/v1 ， 设置
--runtime-config=batch/v1=false - 启用 batch/v2alpha1 , 设置
--runtime-config=batch/v2alpha1
