kubectl技巧之查看資源列表,資源版本和資源schema配置

系列目錄

在kubernetes裏,pod,service,rs,rc,deploy,resource等對象都須要使用yaml文件來建立,不少時候咱們都是參照照官方示例或者一些第三方示例來編寫yaml文件以建立對象.雖然這些示例頗有典型性和表明性,可以知足咱們大部分時候的需求,然而這每每仍是不夠的,根據項目不一樣,實際配置可能遠比官方提供的demo配置複雜的多,這就要求咱們除了掌握經常使用的配置外,還須要對其它配置有所瞭解.若是有一個文檔可以速查某一對象的全部配置,不但方便咱們學習不一樣的配置,也能夠作爲一個小手冊以便咱們記不起來某些配置時能夠速查.

下面咱們介紹一些小技巧來快速查看kubernetes api

查看全部api資源

能夠經過命令kubectl api-resources來查看全部api資源

[centos@k8s-master ~]$ kubectl api-resources
NAME                              SHORTNAMES   APIGROUP                       NAMESPACED   KIND
bindings                                                                      true         Binding
componentstatuses                 cs                                          false        ComponentStatus
configmaps                        cm                                          true         ConfigMap
endpoints                         ep                                          true         Endpoints
events                            ev                                          true         Event
limitranges                       limits                                      true         LimitRange
namespaces                        ns                                          false        Namespace
nodes                             no                                          false        Node
persistentvolumeclaims            pvc                                         true         PersistentVolumeClaim
persistentvolumes                 pv                                          false        PersistentVolume
pods                              po                                          true         Pod
podtemplates                                                                  true         PodTemplate
replicationcontrollers            rc                                          true         ReplicationController
resourcequotas                    quota                                       true         ResourceQuota
secrets                                                                       true         Secret
serviceaccounts                   sa                                          true         ServiceAccount
services                          svc                                         true         Service
mutatingwebhookconfigurations                  admissionregistration.k8s.io   false        MutatingWebhookConfiguration
validatingwebhookconfigurations                admissionregistration.k8s.io   false        ValidatingWebhookConfiguration
customresourcedefinitions         crd,crds     apiextensions.k8s.io           false        CustomResourceDefinition
apiservices                                    apiregistration.k8s.io         false        APIService
controllerrevisions                            apps                           true         ControllerRevision
daemonsets                        ds           apps                           true         DaemonSet
deployments                       deploy       apps                           true         Deployment
replicasets                       rs           apps                           true         ReplicaSet
statefulsets                      sts          apps                           true         StatefulSet
tokenreviews                                   authentication.k8s.io          false        TokenReview
localsubjectaccessreviews                      authorization.k8s.io           true         LocalSubjectAccessReview
selfsubjectaccessreviews                       authorization.k8s.io           false        SelfSubjectAccessReview
selfsubjectrulesreviews                        authorization.k8s.io           false        SelfSubjectRulesReview
subjectaccessreviews                           authorization.k8s.io           false        SubjectAccessReview
horizontalpodautoscalers          hpa          autoscaling                    true         HorizontalPodAutoscaler
cronjobs                          cj           batch                          true         CronJob
jobs                                           batch                          true         Job
certificatesigningrequests        csr          certificates.k8s.io            false        CertificateSigningRequest
leases                                         coordination.k8s.io            true         Lease
events                            ev           events.k8s.io                  true         Event
daemonsets                        ds           extensions                     true         DaemonSet
deployments                       deploy       extensions                     true         Deployment
ingresses                         ing          extensions                     true         Ingress
networkpolicies                   netpol       extensions                     true         NetworkPolicy
podsecuritypolicies               psp          extensions                     false        PodSecurityPolicy
replicasets                       rs           extensions                     true         ReplicaSet
networkpolicies                   netpol       networking.k8s.io              true         NetworkPolicy
poddisruptionbudgets              pdb          policy                         true         PodDisruptionBudget
podsecuritypolicies               psp          policy                         false        PodSecurityPolicy
clusterrolebindings                            rbac.authorization.k8s.io      false        ClusterRoleBinding
clusterroles                                   rbac.authorization.k8s.io      false        ClusterRole
rolebindings                                   rbac.authorization.k8s.io      true         RoleBinding
roles                                          rbac.authorization.k8s.io      true         Role
priorityclasses                   pc           scheduling.k8s.io              false        PriorityClass
storageclasses                    sc           storage.k8s.io                 false        StorageClass
volumeattachments                              storage.k8s.io                 false        VolumeAttachment

除了能夠看到資源的對象名稱外,還能夠看到對象的別名,這時候咱們再看到別人的命令如kubectl get no這樣費解的命令時就能夠知道它實際上表明的是kubectl get nodes命令

查看api的版本,不少yaml配置裏都須要指定配置的資源版本,咱們常常看到v1,beta1,beta2這樣的配置,到底某個資源的最新版本是什麼呢?

其實,能夠經過kubectl api-versions來查看api的版本

[centos@k8s-master ~]$ kubectl api-versions
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
apps/v1beta1
apps/v1beta2
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/v1beta1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1

以上只是總體概況,不少時候咱們還想要看到某個api下面都有哪些配置,某一薦配置的含義等,下面羅列一些經常使用的api範例和一些查看api的技巧

常見範例

• Replica Sets

• Replication Controller

• Deployment

• Service

經過kubectl explain查看api字段

1) 經過kubectl explain <資源名對象名>查看資源對象擁有的字段

前面說過,能夠經過kubectl api-resources來查看資源名稱,若是想要查看某個資源的字段,能夠經過kubectl explain <資源名對象名>來查點它都有哪些字段

[centos@k8s-master ~]$ kubectl explain pod
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.

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

   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

   spec <Object>
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#spec-and-status

   status       <Object>
     Most recently observed status of the pod. This data may not be up to date.
     Populated by the system. Read-only. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#spec-and-status

[centos@k8s-master ~]$

以上Description是對資源對象的簡要描述,Fields則是對全部字段的描述

2) 列出全部api字段

經過以上咱們能感受到,以上好像並無羅列出全部的api字段,實際上以上列出的僅是一級字段,一級字段可能還包含二級的,三級的字段,想要羅列出全部的字段,能夠加上--recursive來列出全部可能的字段

[centos@k8s-master ~]$ kubectl explain svc --recursive
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   <string>
   kind <string>
   metadata     <Object>
      annotations       <map[string]string>
      clusterName       <string>
      creationTimestamp <string>
      deletionGracePeriodSeconds        <integer>
      deletionTimestamp <string>
      finalizers        <[]string>
      generateName      <string>
      generation        <integer>
      initializers      <Object>
         pending        <[]Object>
            name        <string>
         result <Object>
            apiVersion  <string>
            code        <integer>
            details     <Object>
               causes   <[]Object>
                  field <string>
                  message       <string>
                  reason        <string>
               group    <string>
               kind     <string>
               name     <string>
               retryAfterSeconds        <integer>
               uid      <string>
            kind        <string>
            message     <string>
            metadata    <Object>
               continue <string>
               resourceVersion  <string>
               selfLink <string>
            reason      <string>
            status      <string>
      labels    <map[string]string>
      name      <string>
      namespace <string>
      ownerReferences   <[]Object>
         apiVersion     <string>
         blockOwnerDeletion     <boolean>
         controller     <boolean>
         kind   <string>
         name   <string>
         uid    <string>
      resourceVersion   <string>
      selfLink  <string>
      uid       <string>
   spec <Object>
      clusterIP <string>
      externalIPs       <[]string>
      externalName      <string>
      externalTrafficPolicy     <string>
      healthCheckNodePort       <integer>
      loadBalancerIP    <string>
      loadBalancerSourceRanges  <[]string>
      ports     <[]Object>
         name   <string>
         nodePort       <integer>
         port   <integer>
         protocol       <string>
         targetPort     <string>
      publishNotReadyAddresses  <boolean>
      selector  <map[string]string>
      sessionAffinity   <string>
      sessionAffinityConfig     <Object>
         clientIP       <Object>
            timeoutSeconds      <integer>
      type      <string>
   status       <Object>
      loadBalancer      <Object>
         ingress        <[]Object>
            hostname    <string>
            ip  <string>
[centos@k8s-master ~]$

以上輸出的內容是通過格式化了的,咱們能夠根據縮進很容易看到某一個字段從屬於關係

查看具體字段

經過上面kubectl explain service --recursive能夠看到全部的api名稱,可是以上僅僅是羅列了全部的api名稱,若是想要知道某一個api名稱的詳細信息,則能夠經過kubectl explain <資源對象名稱.api名稱>的方式來查看,好比如下示例能夠查看到service下的spec下的ports字段的信息

[centos@k8s-master ~]$ kubectl explain svc.spec.ports
KIND:     Service
VERSION:  v1

RESOURCE: ports <[]Object>

DESCRIPTION:
     The list of ports that are exposed by this service. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies

     ServicePort contains information on service's port.

FIELDS:
   name <string>
     The name of this port within the service. This must be a DNS_LABEL. All
     ports within a ServiceSpec must have unique names. This maps to the 'Name'
     field in EndpointPort objects. Optional if only one ServicePort is defined
     on this service.

   nodePort     <integer>
     The port on each node on which this service is exposed when type=NodePort
     or LoadBalancer. Usually assigned by the system. If specified, it will be
     allocated to the service if unused or else creation of the service will
     fail. Default is to auto-allocate a port if the ServiceType of this Service
     requires one. More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#type-nodeport

   port <integer> -required-
     The port that will be exposed by this service.

   protocol     <string>
     The IP protocol for this port. Supports "TCP", "UDP", and "SCTP". Default
     is TCP.

   targetPort   <string>
     Number or name of the port to access on the pods targeted by the service.
     Number must be in the range 1 to 65535. Name must be an IANA_SVC_NAME. If
     this is a string, it will be looked up as a named port in the target Pod's
     container ports. If this is not specified, the value of the 'port' field is
     used (an identity map). This field is ignored for services with
     clusterIP=None, and should be omitted or set equal to the 'port' field.
     More info:
     https://kubernetes.io/docs/concepts/services-networking/service/#defining-a-service