kubernetes管理集群系列之命令行工具kubectl详解（二）
顾嘉纳
前言：
一个k8s集群搭建完毕后，仅仅是万里长征的第一步，不管是以什么方式搭建的集群，比如，kubeadm或者二进制安装的，也不管是多master集群还是单master集群，不管是生产环境还是测试环境，集群搭建的目的都是为了使用这个集群。（集群搭建是比较基础的问题，在此不予讨论了）
k8s集群不同于其他的容器管理平台，比如，openstack，openstack可以有更多的管理选择比如api，但k8s使用最多也最频繁的是命令行工具kubectl。因此，kubectl能否正确使用，能否熟练使用将会影响到你对集群管理的效率。
正文：
一，
kubectl命令alias为 k
通常为了简化命令，我们可以使用alias命令将kubectl简化为k，本文后续将全部使用k代替kubectl。alias也非常简单。
[root@master ~]# whereis kubectl
kubectl: /usr/bin/kubectl
echo "alias k=/usr/bin/kubectl">>/etc/profile
source /etc/profile先查询出kubectl所在位置，然后将alias写入环境变量配置里，激活环境变量即可。
二，
kubectl的帮助
[root@master ~]# k --help
kubectl controls the Kubernetes cluster manager.
Find more information at: https://kubernetes.io/docs/reference/kubectl/overview/
Basic Commands (Beginner):
create Create a resource from a file or from stdin.
expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
run Run a particular image on the cluster
set Set specific features on objects
Basic Commands (Intermediate):
explain Documentation of resources
get Display one or many resources
edit Edit a resource on the server
delete Delete resources by filenames, stdin, resources and names, or by resources and label selector
Deploy Commands:
rollout Manage the rollout of a resource
scale Set a new size for a Deployment, ReplicaSet or Replication Controller
autoscale Auto-scale a Deployment, ReplicaSet, or ReplicationController
Cluster Management Commands:
certificate Modify certificate resources.
cluster-info Display cluster info
top Display Resource (CPU/Memory/Storage) usage.
cordon Mark node as unschedulable
uncordon Mark node as schedulable
drain Drain node in preparation for maintenance
taint Update the taints on one or more nodes
Troubleshooting and Debugging Commands:
describe Show details of a specific resource or group of resources
logs Print the logs for a container in a pod
attach Attach to a running container
exec Execute a command in a container
port-forward Forward one or more local ports to a pod
proxy Run a proxy to the Kubernetes API server
cp Copy files and directories to and from containers.
auth Inspect authorization
Advanced Commands:
diff Diff live version against would-be applied version
apply Apply a configuration to a resource by filename or stdin
patch Update field(s) of a resource using strategic merge patch
replace Replace a resource by filename or stdin
wait Experimental: Wait for a specific condition on one or many resources.
convert Convert config files between different API versions
kustomize Build a kustomization target from a directory or a remote url.
Settings Commands:
label Update the labels on a resource
annotate Update the annotations on a resource
completion Output shell completion code for the specified shell (bash or zsh)
Other Commands:
alpha Commands for features in alpha
api-resources Print the supported API resources on the server
api-versions Print the supported API versions on the server, in the form of "group/version"
config Modify kubeconfig files
plugin Provides utilities for interacting with plugins.
version Print the client and server version information
Usage:
kubectl [flags] [options]
Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).
很多同学看到某个命令茫茫多的参数，估计就菊花一紧，其实，不用慌，大部分都是不经常使用的，常用的也就那么几个参数。不过，从另一个方面来说，参数多，说明这个命令功能强大嘛，能干的事情非常多，也说明了k8s的复杂性。
这里要说一下，该命令帮助贴心的说明了有哪些部分，比如，
Basic Commands (Beginner)----------基础命令，最基础的命令， 这些命令应该全部掌握
Basic Commands (Intermediate)------------基础命令，中度使用命令，这些命令也应该全部掌握
Deploy Commands----------部署命令，这些命令需要掌握，autoscale除外
Cluster Management Commands---------集群管理命令，cluster-info，top，taint需要熟练掌握。
Troubleshooting and Debugging Commands---------debug和总结报告类型的命令 describe，logs，exec，port-forward，proxy需要熟练掌握
Advanced Commands------------高级进阶命令，apply，patch，replace，需要熟练掌握
Settings Commands----------------基本设置命令，label，annotate，completion需要熟练掌握
Other Commands--------------------其它类型的命令，api-resources，api-version,config,version,plugin需要熟练掌握三，
k8s常用参数
-
Basic Commands (Beginner): create Create a resource from a file or from stdin.这个是非常常用的参数，比如下面这个命令，将会快速的部署一个NGINX到集群内：
k create deployment nginx --image nginx:1.19此时查看pod，会发现是这样的：
kube-system kube-scheduler-c7n.cnn 1/1 Running 0 122m
[root@master ~]# k get pods -A
NAMESPACE NAME READY STATUS RESTARTS AGE
database mysql2-5db57c8bc8-7bwbg 1/1 Running 3 3d18h
default nfs-client-provisioner-6fc484bd4f-pjxm7 1/1 Running 2 2d23h
default nginx-7b54d48599-x2zc5 0/1 ContainerCreating 0 33s
containercreating表示正在拉取镜像，生成pod ，等待镜像拉取完成后，将端口暴露出来：
[root@master ~]# k expose deployment nginx --port 80 --type NodePort
service/nginx exposed
此时，将会有一个service建立，并且在集群外的机器上可以访问到这个pod了，30067就是刚才建立的pod暴露的端口号：
[root@master ~]# k get svc -A
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
database mysql2 NodePort 10.106.38.0 <none> 3306:32222/TCP 3d18h
default kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 27d
default nginx NodePort 10.96.201.101 <none> 80:30067/TCP 73s
此时，打开浏览器输入任意一个集群内所在机器的ip+端口号30067就可以访问到nginx的首页啦。
-
资源清单
k api-resources
[root@master ~]# k 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
endpointslices discovery.k8s.io true EndpointSlice
events ev events.k8s.io true Event
ingresses ing extensions true Ingress
ingressclasses networking.k8s.io false IngressClass
ingresses ing networking.k8s.io true Ingress
networkpolicies netpol networking.k8s.io true NetworkPolicy
runtimeclasses node.k8s.io false RuntimeClass
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
csidrivers storage.k8s.io false CSIDriver
csinodes storage.k8s.io false CSINode
storageclasses sc storage.k8s.io false StorageClass
volumeattachments storage.k8s.io false VolumeAttachment
这个命令是在Other Commands里面的，直接 kubectl api-resources，这个非常重要，k8s的管理其实也主要是围绕着各种各样的资源来管理的。
第一列是所有k8s里的资源名称，常见的比如namespace，pods，nodes，StorageClass，service，statefulsets，deployments等等。
第二列是资源的缩写，比如，services=svc，pods=po，StorageClass=sc，PersistentVolumeClaim=pvc，PersistentVolume=pv等等。因此，比如查询所有namespaces有哪些，命令可以简化成这样：
[root@master ~]# k get ns
NAME STATUS AGE
database Active 3d23h
default Active 27d
kube-node-lease Active 27d
kube-public Active 27d
kube-system Active 27d
查询所有的pods，命令可以简化成这样：
[root@master ~]# k get po -A
NAMESPACE NAME READY STATUS RESTARTS AGE
database mysql2-5db57c8bc8-7bwbg 1/1 Running 4 3d23h
default nfs-client-provisioner-6fc484bd4f-pjxm7 1/1 Running 3 3d4h
default nginx-7b54d48599-x2zc5 1/1 Running 1 4h41m
default test-pod 0/1 Pending 0 3d4h
kube-system coredns-6c76c8bb89-tfcrm 1/1 Running 5 27d
kube-system coredns-6c76c8bb89-vnlwg 1/1 Running 5 27d
kube-system etcd-c7n.cnn 1/1 Running 6 27d
kube-system kube-apiserver-c7n.cnn 1/1 Running 5 3d21h
kube-system kube-controller-manager-c7n.cnn 1/1 Running 2 6h49m
kube-system kube-flannel-ds-djwmq 1/1 Running 4 4d
kube-system kube-flannel-ds-f5gtd 1/1 Running 5 4d
kube-system kube-flannel-ds-k5jpf 1/1 Running 4 4d
kube-system kube-proxy-7v5mj 1/1 Running 5 27d
kube-system kube-proxy-mtttm 1/1 Running 5 27d
kube-system kube-proxy-zwmwf 1/1 Running 6 27d
kube-system kube-scheduler-c7n.cnn 1/1 Running 1 6h44m
第三例是资源的apigroup，比如编写jobs相关的资源清单文件，apiversion就必须是batch这个apigroup啦，当然，/ 后面还需要通过 k api-versions 这个命令查询。
比如这个定时任务资源清单文件：
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: hello
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: hello
image: busybox
args:
- /bin/sh
- -c
- date; echo Hello world！！！！！！！
restartPolicy: OnFailure
第四列是资源是否必须和namespace关联，比如，nodes就不能通过namespace隔离，但pods可以通过namespace隔离，假如有两个不同的namespace A和Bnamespace，k8s会认为 A中运行的nginx-1.20.1和B中运行的nginx-1.20.1是两个不同的pod，并且在定义或者使用这些资源的时候，如果该列为true值，那么，必须要指定namespace，否则使用default这个namespace，如果该列为false值，那么，在定义资源的时候不需要指定namespace。
第五列是资源定义的时候kind的值，比如，要定义一个jobs资源，kind的值必须是Job（注意，这里是区分大小写的哦，切记！！！！！！），上面示例的第二行cronjob对应的kind的值就必须是CronJob 。
-
版本清单
k api-versions，通过此命令可查询出现有的k8s集群所支持的kind版本。上面那个cronjob文件为例，可以知道，我这个集群，资源清单文件首行可以写成：apiVersion: batch/v1beta1 也可以写成apiVersion: batch/v1 这样的形式，在这个集群内都是OK的。
[root@master ~]# k 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/v1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1
coordination.k8s.io/v1beta1
discovery.k8s.io/v1beta1
events.k8s.io/v1
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
- Basic Commands (Intermediate)里的get参数
kubectl命令里的get参数是使用频率最高的，没有之一，kubectl get --help 是该参数的详细介绍：
[root@master ~]# k get --help
Display one or many resources
Prints a table of the most important information about the specified resources. You can filter the list using a label
selector and the --selector flag. If the desired resource type is namespaced you will only see results in your current
namespace unless you pass --all-namespaces.
Uninitialized objects are not shown unless --include-uninitialized is passed.
By specifying the output as 'template' and providing a Go template as the value of the --template flag, you can filter
the attributes of the fetched resources.
Use "kubectl api-resources" for a complete list of supported resources.
Examples:
# List all pods in ps output format.
kubectl get pods
# List all pods in ps output format with more information (such as node name).
kubectl get pods -o wide
# List a single replication controller with specified NAME in ps output format.
kubectl get replicationcontroller web
# List deployments in JSON output format, in the "v1" version of the "apps" API group:
kubectl get deployments.v1.apps -o json
# List a single pod in JSON output format.
kubectl get -o json pod web-pod-13je7
# List a pod identified by type and name specified in "pod.yaml" in JSON output format.
kubectl get -f pod.yaml -o json
# List resources from a directory with kustomization.yaml - e.g. dir/kustomization.yaml.
kubectl get -k dir/
# Return only the phase value of the specified pod.
kubectl get -o template pod/web-pod-13je7 --template={{.status.phase}}
# List resource information in custom columns.
kubectl get pod test-pod -o custom-columns=CONTAINER:.spec.containers[0].name,IMAGE:.spec.containers[0].image
# List all replication controllers and services together in ps output format.
kubectl get rc,services
# List one or more resources by their type and names.
kubectl get rc/web service/frontend pods/web-pod-13je7
Options:
-A, --all-namespaces=false: If present, list the requested object(s) across all namespaces. Namespace in current
context is ignored even if specified with --namespace.
--allow-missing-template-keys=true: If true, ignore any errors in templates when a field or map key is missing in
the template. Only applies to golang and jsonpath output formats.
--chunk-size=500: Return large lists in chunks rather than all at once. Pass 0 to disable. This flag is beta and
may change in the future.
--field-selector='': Selector (field query) to filter on, supports '=', '==', and '!='.(e.g. --field-selector
key1=value1,key2=value2). The server only supports a limited number of field queries per type.
-f, --filename=[]: Filename, directory, or URL to files identifying the resource to get from a server.
--ignore-not-found=false: If the requested object does not exist the command will return exit code 0.
-k, --kustomize='': Process the kustomization directory. This flag can't be used together with -f or -R.
-L, --label-columns=[]: Accepts a comma separated list of labels that are going to be presented as columns. Names are
case-sensitive. You can also use multiple flag options like -L label1 -L label2...
--no-headers=false: When using the default or custom-column output format, don't print headers (default print
headers).
-o, --output='': Output format. One of:
json|yaml|wide|name|custom-columns=...|custom-columns-file=...|go-template=...|go-template-file=...|jsonpath=...|jsonpath-file=...
See custom columns [http://kubernetes.io/docs/user-guide/kubectl-overview/#custom-columns], golang template
[http://golang.org/pkg/text/template/#pkg-overview] and jsonpath template
[http://kubernetes.io/docs/user-guide/jsonpath].
--output-watch-events=false: Output watch event objects when --watch or --watch-only is used. Existing objects are
output as initial ADDED events.
--raw='': Raw URI to request from the server. Uses the transport specified by the kubeconfig file.
-R, --recursive=false: Process the directory used in -f, --filename recursively. Useful when you want to manage
related manifests organized within the same directory.
-l, --selector='': Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)
--server-print=true: If true, have the server return the appropriate table output. Supports extension APIs and
CRDs.
--show-kind=false: If present, list the resource type for the requested object(s).
--show-labels=false: When printing, show all labels as the last column (default hide labels column)
--sort-by='': If non-empty, sort list types using this field specification. The field specification is expressed
as a JSONPath expression (e.g. '{.metadata.name}'). The field in the API resource specified by this JSONPath expression
must be an integer or a string.
--template='': Template string or path to template file to use when -o=go-template, -o=go-template-file. The
template format is golang templates [http://golang.org/pkg/text/template/#pkg-overview].
-w, --watch=false: After listing/getting the requested object, watch for changes. Uninitialized objects are excluded
if no object name is provided.
--watch-only=false: Watch for changes to the requested object(s), without listing/getting first.
Usage:
kubectl get
[(-o|--output=)json|yaml|wide|custom-columns=...|custom-columns-file=...|go-template=...|go-template-file=...|jsonpath=...|jsonpath-file=...]
(TYPE[.VERSION][.GROUP] [NAME | -l label] | TYPE[.VERSION][.GROUP]/NAME ...) [flags] [options]
Use "kubectl options" for a list of global command-line options (applies to all commands).
该帮助给出了一些例子，总的来说，k get resource 名称即可，例如：
副本控制器 replicationcontrollers
[root@master ~]# k get rs -A
NAMESPACE NAME DESIRED CURRENT READY AGE
database mysql2-5db57c8bc8 1 1 1 4d
default nfs-client-provisioner-556768d99f 0 0 0 4d1h
default nfs-client-provisioner-5bd5bb49f 0 0 0 4d
default nfs-client-provisioner-5c786944fc 0 0 0 4d1h
default nfs-client-provisioner-6fc484bd4f 1 1 1 3d5h
default nfs-client-provisioner-75ffb44498 0 0 0 4d
default nfs-client-provisioner-7d8bb64cc 0 0 0 3d23h
default nfs-client-provisioner-d7d7f8859 0 0 0 3d23h
default nginx-7b54d48599 1 1 1 5h48m
kube-system coredns-6c76c8bb89 2 2 2 27d
例如查询集群内所有角色：
[root@master ~]# k get clusterroles -A
NAME CREATED AT
admin 2022-06-13T02:56:43Z
cluster-admin 2022-06-13T02:56:43Z
edit 2022-06-13T02:56:43Z
flannel 2022-07-06T08:07:44Z
kubeadm:get-nodes 2022-06-13T02:56:45Z
nfs-provisioner-runner 2022-07-06T08:09:42Z
system:aggregate-to-admin 2022-06-13T02:56:43Z
system:aggregate-to-edit 2022-06-13T02:56:43Z
system:aggregate-to-view 2022-06-13T02:56:43Z
system:auth-delegator 2022-06-13T02:56:43Z
system:basic-user 2022-06-13T02:56:43Z
system:certificates.k8s.io:certificatesigningrequests:nodeclient 2022-06-13T02:56:43Z
system:certificates.k8s.io:certificatesigningrequests:selfnodeclient 2022-06-13T02:56:43Z
system:certificates.k8s.io:kube-apiserver-client-approver 2022-06-13T02:56:43Z
system:certificates.k8s.io:kube-apiserver-client-kubelet-approver 2022-06-13T02:56:43Z
system:certificates.k8s.io:kubelet-serving-approver 2022-06-13T02:56:43Z
system:certificates.k8s.io:legacy-unknown-approver 2022-06-13T02:56:43Z
system:controller:attachdetach-controller 2022-06-13T02:56:43Z
system:controller:certificate-controller 2022-06-13T02:56:44Z
system:controller:clusterrole-aggregation-controller 2022-06-13T02:56:43Z
system:controller:cronjob-controller 2022-06-13T02:56:43Z
system:controller:daemon-set-controller 2022-06-13T02:56:44Z
system:controller:deployment-controller 2022-06-13T02:56:44Z
system:controller:disruption-controller 2022-06-13T02:56:44Z
system:controller:endpoint-controller 2022-06-13T02:56:44Z
system:controller:endpointslice-controller 2022-06-13T02:56:44Z
system:controller:endpointslicemirroring-controller 2022-06-13T02:56:44Z
system:controller:expand-controller 2022-06-13T02:56:44Z
system:controller:generic-garbage-collector 2022-06-13T02:56:44Z
system:controller:horizontal-pod-autoscaler 2022-06-13T02:56:44Z
system:controller:job-controller 2022-06-13T02:56:44Z
system:controller:namespace-controller 2022-06-13T02:56:44Z
system:controller:node-controller 2022-06-13T02:56:44Z
system:controller:persistent-volume-binder 2022-06-13T02:56:44Z
system:controller:pod-garbage-collector 2022-06-13T02:56:44Z
system:controller:pv-protection-controller 2022-06-13T02:56:44Z
system:controller:pvc-protection-controller 2022-06-13T02:56:44Z
system:controller:replicaset-controller 2022-06-13T02:56:44Z
system:controller:replication-controller 2022-06-13T02:56:44Z
system:controller:resourcequota-controller 2022-06-13T02:56:44Z
system:controller:route-controller 2022-06-13T02:56:44Z
system:controller:service-account-controller 2022-06-13T02:56:44Z
system:controller:service-controller 2022-06-13T02:56:44Z
system:controller:statefulset-controller 2022-06-13T02:56:44Z
system:controller:ttl-controller 2022-06-13T02:56:44Z
system:coredns 2022-06-13T02:56:45Z
system:discovery 2022-06-13T02:56:43Z
system:heapster 2022-06-13T02:56:43Z
system:kube-aggregator 2022-06-13T02:56:43Z
system:kube-controller-manager 2022-06-13T02:56:43Z
system:kube-dns 2022-06-13T02:56:43Z
system:kube-scheduler 2022-06-13T02:56:43Z
system:kubelet-api-admin 2022-06-13T02:56:43Z
system:node 2022-06-13T02:56:43Z
system:node-bootstrapper 2022-06-13T02:56:43Z
system:node-problem-detector 2022-06-13T02:56:43Z
system:node-proxier 2022-06-13T02:56:43Z
system:persistent-volume-provisioner 2022-06-13T02:56:43Z
system:public-info-viewer 2022-06-13T02:56:43Z
system:volume-scheduler 2022-06-13T02:56:43Z
view 2022-06-13T02:56:43Z
查询角色绑定情况：
[root@master ~]# k get rolebindings -A
NAMESPACE NAME ROLE AGE
kube-public kubeadm:bootstrap-signer-clusterinfo Role/kubeadm:bootstrap-signer-clusterinfo 27d
kube-public system:controller:bootstrap-signer Role/system:controller:bootstrap-signer 27d
kube-system kube-proxy Role/kube-proxy 27d
kube-system kubeadm:kubelet-config-1.19 Role/kubeadm:kubelet-config-1.19 27d
kube-system kubeadm:nodes-kubeadm-config Role/kubeadm:nodes-kubeadm-config 27d
kube-system system::extension-apiserver-authentication-reader Role/extension-apiserver-authentication-reader 27d
kube-system system::leader-locking-kube-controller-manager Role/system::leader-locking-kube-controller-manager 27d
kube-system system::leader-locking-kube-scheduler Role/system::leader-locking-kube-scheduler 27d
kube-system system:controller:bootstrap-signer Role/system:controller:bootstrap-signer 27d
kube-system system:controller:cloud-provider Role/system:controller:cloud-provider 27d
kube-system system:controller:token-cleaner Role/system:controller:token-cleaner 27d
这里注意一点，查询所有 后面加个 -A 或者--all 都可以的哦：
[root@master ~]# k get rolebindings -A
NAMESPACE NAME ROLE AGE
kube-public kubeadm:bootstrap-signer-clusterinfo Role/kubeadm:bootstrap-signer-clusterinfo 27d
kube-public system:controller:bootstrap-signer Role/system:controller:bootstrap-signer 27d
kube-system kube-proxy Role/kube-proxy 27d
kube-system kubeadm:kubelet-config-1.19 Role/kubeadm:kubelet-config-1.19 27d
kube-system kubeadm:nodes-kubeadm-config Role/kubeadm:nodes-kubeadm-config 27d
kube-system system::extension-apiserver-authentication-reader Role/extension-apiserver-authentication-reader 27d
kube-system system::leader-locking-kube-controller-manager Role/system::leader-locking-kube-controller-manager 27d
kube-system system::leader-locking-kube-scheduler Role/system::leader-locking-kube-scheduler 27d
kube-system system:controller:bootstrap-signer Role/system:controller:bootstrap-signer 27d
kube-system system:controller:cloud-provider Role/system:controller:cloud-provider 27d
kube-system system:controller:token-cleaner Role/system:controller:token-cleaner 27d
官方的帮助文档其实已经非常详细了，在此我就抛砖引玉一下，只需要记住，k get resource名称 -A ，如果该资源有，那么就可以查询到，如果没有，它也会提示的哦，在比如，集群报错信息：
[root@master ~]# k get events -A
NAMESPACE LAST SEEN TYPE REASON OBJECT MESSAGE
default 8s Normal ExternalProvisioning persistentvolumeclaim/test-claim waiting for a volume to be created, either by external provisioner "fuseim.pri/ifs" or manually created by system administrator
default 11m Warning FailedScheduling pod/test-pod 0/3 nodes are available: 3 pod has unbound immediate PersistentVolumeClaims.
根据以上提示，在查询pvc，可以看到现在有pvc状态是不对的：
[root@master ~]# k get pvc -A
NAMESPACE NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
database nfs-pvc-test Bound nfs-pv-test1 1536Mi RWO nfs 4d
default test-claim Pending managed-nfs-storage 3d5h
- Troubleshooting and Debugging Commands里的describe和logs参数
describe和logs是在集群的使用过程中，各种各样的资源有可能会出现问题，此时，debug追踪查看问题原因时使用，也是使用非常多的参数
例如，k describe --help的帮助：
[root@master ~]# k describe --help
Show details of a specific resource or group of resources
Print a detailed description of the selected resources, including related resources such as events or controllers. You
may select a single object by name, all objects of that type, provide a name prefix, or label selector. For example:
$ kubectl describe TYPE NAME_PREFIX
will first check for an exact match on TYPE and NAME_PREFIX. If no such resource exists, it will output details for
every resource that has a name prefixed with NAME_PREFIX.
Use "kubectl api-resources" for a complete list of supported resources.
Examples:
# Describe a node
kubectl describe nodes kubernetes-node-emt8.c.myproject.internal
# Describe a pod
kubectl describe pods/nginx
# Describe a pod identified by type and name in "pod.json"
kubectl describe -f pod.json
# Describe all pods
kubectl describe pods
# Describe pods by label name=myLabel
kubectl describe po -l name=myLabel
# Describe all pods managed by the 'frontend' replication controller (rc-created pods
# get the name of the rc as a prefix in the pod the name).
kubectl describe pods frontend
Options:
-A, --all-namespaces=false: If present, list the requested object(s) across all namespaces. Namespace in current
context is ignored even if specified with --namespace.
-f, --filename=[]: Filename, directory, or URL to files containing the resource to describe
-k, --kustomize='': Process the kustomization directory. This flag can't be used together with -f or -R.
-R, --recursive=false: Process the directory used in -f, --filename recursively. Useful when you want to manage
related manifests organized within the same directory.
-l, --selector='': Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)
--show-events=true: If true, display events related to the described object.
Usage:
kubectl describe (-f FILENAME | TYPE [NAME_PREFIX | -l label] | TYPE/NAME) [options]
Use "kubectl options" for a list of global command-line options (applies to all commands).
同样的，该参数也有详细的说明并且有一些简单的示例，例如查询本集群的slave1节点的详细信息：
[root@master ~]# k describe nodes slave1
Name: slave1
Roles: <none>
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/arch=amd64
kubernetes.io/hostname=slave1
kubernetes.io/os=linux
Annotations: flannel.alpha.coreos.com/backend-data: {"VtepMAC":"52:04:85:12:ca:e2"}
flannel.alpha.coreos.com/backend-type: vxlan
flannel.alpha.coreos.com/kube-subnet-manager: true
flannel.alpha.coreos.com/public-ip: 192.168.217.17
kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
node.alpha.kubernetes.io/ttl: 0
volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp: Mon, 13 Jun 2022 10:57:25 +0800
Taints: <none>
Unschedulable: false
Lease:
HolderIdentity: slave1
AcquireTime: <unset>
RenewTime: Sun, 10 Jul 2022 17:42:22 +0800
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
NetworkUnavailable False Sun, 10 Jul 2022 15:52:41 +0800 Sun, 10 Jul 2022 15:52:41 +0800 FlannelIsUp Flannel is running on this node
MemoryPressure False Sun, 10 Jul 2022 17:38:35 +0800 Mon, 13 Jun 2022 10:57:26 +0800 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Sun, 10 Jul 2022 17:38:35 +0800 Mon, 13 Jun 2022 10:57:26 +0800 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Sun, 10 Jul 2022 17:38:35 +0800 Mon, 13 Jun 2022 10:57:26 +0800 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Sun, 10 Jul 2022 17:38:35 +0800 Mon, 13 Jun 2022 10:57:36 +0800 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 192.168.217.17
Hostname: slave1
Capacity:
cpu: 8
ephemeral-storage: 10230Mi
hugepages-2Mi: 0
memory: 4026340Ki
pods: 110
Allocatable:
cpu: 8
ephemeral-storage: 9654239217
hugepages-2Mi: 0
memory: 3923940Ki
pods: 110
System Info:
Machine ID: 9e1e6e06c15e4e43a32b308f9e7106fa
System UUID: 2ed24d56-5e02-0ef6-f3fc-b3acc3e99e89
Boot ID: 6e80cbd7-8f7d-46cc-9458-cb040dbf3206
Kernel Version: 5.16.9-1.el7.elrepo.x86_64
OS Image: CentOS Linux 7 (Core)
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://20.10.7
Kubelet Version: v1.19.4
Kube-Proxy Version: v1.19.4
PodCIDR: 10.244.1.0/24
PodCIDRs: 10.244.1.0/24
Non-terminated Pods: (5 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
database mysql2-5db57c8bc8-7bwbg 0 (0%) 0 (0%) 0 (0%) 0 (0%) 4d
default nginx-7b54d48599-x2zc5 0 (0%) 0 (0%) 0 (0%) 0 (0%) 6h9m
kube-system coredns-6c76c8bb89-tfcrm 100m (1%) 0 (0%) 70Mi (1%) 170Mi (4%) 27d
kube-system kube-flannel-ds-djwmq 100m (1%) 100m (1%) 50Mi (1%) 50Mi (1%) 4d1h
kube-system kube-proxy-mtttm 0 (0%) 0 (0%) 0 (0%) 0 (0%) 27d
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 200m (2%) 100m (1%)
memory 120Mi (3%) 220Mi (5%)
ephemeral-storage 0 (0%) 0 (0%)
hugepages-2Mi 0 (0%) 0 (0%)
Events: <none>
该节点的非常详细的信息都查询出来了，比如，运行了哪些pod，当然，我们也可以使用组合命令来查询slave1到底有运行哪些pod，但是，describe是把非常多的信息都给列出来了啊：
[root@master ~]# k get pods -A -o wide |grep slave1
database mysql2-5db57c8bc8-7bwbg 1/1 Running 4 4d 10.244.1.14 slave1 <none> <none>
default nginx-7b54d48599-x2zc5 1/1 Running 1 6h12m 10.244.1.12 slave1 <none> <none>
kube-system coredns-6c76c8bb89-tfcrm 1/1 Running 5 27d 10.244.1.13 slave1 <none> <none>
kube-system kube-flannel-ds-djwmq 1/1 Running 4 4d1h 192.168.217.17 slave1 <none> <none>
kube-system kube-proxy-mtttm 1/1 Running 5 27d 192.168.217.17 slave1 <none> <none>
两个命令可以互相印证的哦，k describe node slave1 里关于slave1里有哪些pods和 k get pods -A -o wide |grep slave1 结果是一致的哦。
还有一些别的参数，比如logs，apply等等参数，都可以通过--help查询出来具体的用法，在此就不献丑了。
总结：
kubectl 命令参数非常多，但常用的应该也就十来个吧，大体上是有这样一些常用参数：
describe，get，apply，taint，create，run，logs，delete，api-version,version,api-resources,rollout,scale,edit,expose,replace
如有遗漏，欢迎补充哦
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