使用kubectl管理Kubernetes（k8s）集群常用命令查看负载命名空间

　　一.系统环境
　　服务器版本
　　docker软件版本
　　CPU架构
　　CentOS Linux release 7.4.1708 (Core)
　　Docker version 20.10.12
　　x86_64  二.前言
　　kubectl是Kubernetes提供的命令行工具，kubectl 使用 Kubernetes API 与 Kubernetes 集群的控制面进行通信。
　　针对配置信息，kubectl 在 $HOME/.kube 目录中查找一个名为 config 的配置文件来连接Kubernetes 集群。 你可以通过设置 KUBECONFIG 环境变量或设置 --kubeconfig 参数来指定其它 kubeconfig 文件。
　　使用kubectl命令行工具的   前提   是已经有一套可以正常运行的Kubernetes集群，关于Kubernetes(k8s)集群的安装部署  三.kubectl3.1 kubectl语法
　　kubectl的语法为：   kubectl [command] [TYPE] [NAME] [flags]   ，其中 command、TYPE、NAME 和 flags 分别是：  command：指定要对一个或多个资源执行的操作，例如 create、get、describe、delete。  TYPE：指定资源类型。资源类型不区分大小写， 可以指定单数、复数或缩写形式。例如，以下命令输出相同的结果：  kubectl   get   pod pod1 kubectl  get   pods pod1 kubectl  get    po   pod1 NAME：指定资源的名称。名称区分大小写。 如果省略名称，则显示所有资源的详细信息。例如：kubectl get pods。flags： 指定可选的参数。例如，可以使用 -s 或 --server 参数指定 Kubernetes API 服务器的地址和端口。
　　要对所有类型相同的资源进行分组，请执行以下操作：TYPE1 name1 name2 name<#>。
　　例子：kubectl get pod example-pod1 example-pod2
　　分别指定多个资源类型：TYPE1/name1 TYPE1/name2 TYPE2/name3 TYPE<#>/name<#>。
　　例子：kubectl get pod/example-pod1 replicationcontroller/example-rc1  3.2 kubectl格式化输出
　　kubectl格式化输出语法：   kubectl [command] [TYPE] [NAME] -o
　　输出格式
　　描述
　　-o custom-columns=spec
　　使用逗号分隔的自定义列列表打印表。
　　-o custom-columns-file=filename
　　使用 filename文件中的自定义列模板打印表。
　　-o json
　　输出 JSON 格式的 API 对象
　　-o jsonpath=template
　　打印 jsonpath 表达式定义的字段
　　-o jsonpath-file=filename
　　打印 filename>文件中 jsonpath 表达式定义的字段。
　　-o name
　　仅打印资源名称而不打印任何其他内容。
　　-o wide
　　以纯文本格式输出，包含所有附加信息。对于 Pod 包含节点名。
　　-o yaml
　　输出 YAML 格式的 API 对象。  四.kubectl常用命令
　　查看从什么地址能访问k8s API，会显示k8s集群的master节点的地址  [root@k8scloude1 ~]# kubectl cluster-info  Kubernetes control plane is running at https://192.168.110.130:6443 CoreDNS is running at https://192.168.110.130:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy  To further debug and diagnose cluster problems, use ＂kubectl cluster-info dump＂.
　　查看kubectl版本  [root@k8scloude1 ~]# kubectl version  Client Version: version.Info{Major:＂1＂, Minor:＂21＂, GitVersion:＂v1.21.0＂, GitCommit:＂cb303e613a121a29364f75cc67d3d580833a7479＂, GitTreeState:＂clean＂, BuildDate:＂2021-04-08T16:31:21Z＂, GoVersion:＂go1.16.1＂, Compiler:＂gc＂, Platform:＂linux/amd64＂} Server Version: version.Info{Major:＂1＂, Minor:＂21＂, GitVersion:＂v1.21.0＂, GitCommit:＂cb303e613a121a29364f75cc67d3d580833a7479＂, GitTreeState:＂clean＂, BuildDate:＂2021-04-08T16:25:06Z＂, GoVersion:＂go1.16.1＂, Compiler:＂gc＂, Platform:＂linux/amd64＂}  [root@k8scloude1 ~]# kubectl version --short Client Version: v1.21.0 Server Version: v1.21.0
　　查看k8s的pod网段，可以看到pod网段为10.244.0.0/16  #查看初始化时候的k8s集群配置:kubeadm config view [root@k8scloude1 ~]# kubeadm config view Command ＂view＂ is deprecated, This command is deprecated and will be removed in a future release, please use ＂kubectl get cm -o yaml -n kube-system kubeadm-config＂ to get the kubeadm config directly. apiServer:   extraArgs:     authorization-mode: Node,RBAC   timeoutForControlPlane: 4m0s apiVersion: kubeadm.k8s.io/v1beta2 certificatesDir: /etc/kubernetes/pki clusterName: kubernetes controllerManager: {} dns:   type: CoreDNS etcd:   local:     dataDir: /var/lib/etcd imageRepository: registry.aliyuncs.com/google_containers kind: ClusterConfiguration kubernetesVersion: v1.21.0 networking:   dnsDomain: cluster.local   podSubnet: 10.244.0.0/16   serviceSubnet: 10.96.0.0/12 scheduler: {}
　　查看kubeconfig文件的结构  [root@k8scloude1 ~]# kubectl config view apiVersion: v1 clusters: - cluster:     certificate-authority-data: DATA+OMITTED     server: https://192.168.110.130:6443   name: kubernetes contexts: - context:     cluster: kubernetes     user: kubernetes-admin   name: kubernetes-admin@kubernetes current-context: kubernetes-admin@kubernetes kind: Config preferences: {} users: - name: kubernetes-admin   user:     client-certificate-data: REDACTED     client-key-data: REDACTED五.查看kubernetes集群node节点和pod负载5.1 安装metric-server
　　查看node节点和pod的负载，发现看不了node和pod的负载，是因为没有安装metric-server  [root@k8scloude1 ~]# kubectl top nodes W0109 16:45:38.197980   75467 top_node.go:119] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag error: Metrics API not available  [root@k8scloude1 ~]# kubectl top pods W0109 16:45:58.436117   75718 top_pod.go:140] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag error: Metrics API not available
　　为了查看节点和pod的负载，下面开始安装metric-server
　　创建目录，用来存放metric-server  [root@k8scloude1 ~]# mkdir metric-server  [root@k8scloude1 ~]# cd metric-server/
　　下载metrics-server并解压  [root@k8scloude1 metric-server]# wget https://github.com/kubernetes-sigs/metrics-server/archive/v0.3.6.tar.gz  [root@k8scloude1 metric-server]# ls v0.3.6.tar.gz  [root@k8scloude1 metric-server]# tar xf v0.3.6.tar.gz   [root@k8scloude1 metric-server]# ls metrics-server-0.3.6  v0.3.6.tar.gz  [root@k8scloude1 metric-server]# cd metrics-server-0.3.6/  [root@k8scloude1 metrics-server-0.3.6]# ls cmd  code-of-conduct.md  CONTRIBUTING.md  deploy  Gopkg.lock  Gopkg.toml  hack  LICENSE  Makefile  OWNERS  OWNERS_ALIASES  pkg  README.md  SECURITY_CONTACTS  vendor  version  [root@k8scloude1 metrics-server-0.3.6]# cd deploy/  [root@k8scloude1 deploy]# ls 1.7  1.8+  docker  minikube  [root@k8scloude1 deploy]# cd 1.8+  [root@k8scloude1 1.8+]# ls aggregated-metrics-reader.yaml  auth-delegator.yaml  auth-reader.yaml  metrics-apiservice.yaml  metrics-server-deployment.yaml  metrics-server-service.yaml  resource-reader.yaml
　　查看需要下载的镜像，image: k8s.gcr.io/metrics-server-amd64:v0.3.6这个镜像国内访问不了，我们手动下载一个国内镜像  [root@k8scloude1 1.8+]# grep image metrics-server-deployment.yaml       # mount in tmp so we can safely use from-scratch images and/or read-only containers         image: k8s.gcr.io/metrics-server-amd64:v0.3.6         imagePullPolicy: Always
　　在k8s集群master节点和worker节点都需要下载metrics-server-amd64:v0.3.6镜像  [root@k8scloude1 1.8+]# docker pull mirrorgooglecontainers/metrics-server-amd64:v0.3.6  [root@k8scloude1 1.8+]# docker images | grep mirrorgooglecontainers REPOSITORY                                                        TAG        IMAGE ID       CREATED         SIZE mirrorgooglecontainers/metrics-server-amd64                       v0.3.6     9dd718864ce6   2 years ago     39.9MB
　　镜像已经下好了，现在进行docker tag重命名，并删除原镜像mirrorgooglecontainers/metrics-server-amd64:v0.3.6  [root@k8scloude1 1.8+]# docker tag mirrorgooglecontainers/metrics-server-amd64:v0.3.6 k8s.gcr.io/metrics-server-amd64:v0.3.6  [root@k8scloude1 1.8+]# docker rmi mirrorgooglecontainers/metrics-server-amd64:v0.3.6
　　worker节点也进行相同操作  [root@k8scloude2 ~]# docker pull mirrorgooglecontainers/metrics-server-amd64:v0.3.6  [root@k8scloude2 ~]# docker tag mirrorgooglecontainers/metrics-server-amd64:v0.3.6 k8s.gcr.io/metrics-server-amd64:v0.3.6  [root@k8scloude2 ~]# docker rmi mirrorgooglecontainers/metrics-server-amd64:v0.3.6  [root@k8scloude3 ~]# docker pull mirrorgooglecontainers/metrics-server-amd64:v0.3.6  [root@k8scloude3 ~]# docker tag mirrorgooglecontainers/metrics-server-amd64:v0.3.6 k8s.gcr.io/metrics-server-amd64:v0.3.6  [root@k8scloude3 ~]# docker rmi mirrorgooglecontainers/metrics-server-amd64:v0.3.6
　　修改配置文件，镜像下载策略imagePullPolicy改为IfNotPresent，IfNotPresent表示只有当镜像在本地不存在时才会拉取  [root@k8scloude1 1.8+]# pwd /root/metric-server/metrics-server-0.3.6/deploy/1.8+  #修改内容如下： imagePullPolicy: IfNotPresent #        command: #      - /metrics-server #        - --metric-resolution=30s #        - --kubelet-insecure-tls #        - --kubelet-preferred-address-types=InternalIP [root@k8scloude1 1.8+]# tail -20 metrics-server-deployment.yaml         k8s-app: metrics-server     spec:       serviceAccountName: metrics-server       volumes:       # mount in tmp so we can safely use from-scratch images and/or read-only containers       - name: tmp-dir         emptyDir: {}       containers:       - name: metrics-server         image: k8s.gcr.io/metrics-server-amd64:v0.3.6         imagePullPolicy: IfNotPresent         command:         - /metrics-server         - --metric-resolution=30s         - --kubelet-insecure-tls         - --kubelet-preferred-address-types=InternalIP         volumeMounts:         - name: tmp-dir           mountPath: /tmp
　　安装metrics-server  #kubectl apply -f .    .表示安装当前目录下的所有文件 [root@k8scloude1 1.8+]# kubectl apply -f . clusterrole.rbac.authorization.k8s.io/system:aggregated-metrics-reader created 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/metrics-server:system:auth-delegator created Warning: rbac.authorization.k8s.io/v1beta1 RoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 RoleBinding rolebinding.rbac.authorization.k8s.io/metrics-server-auth-reader created Warning: apiregistration.k8s.io/v1beta1 APIService is deprecated in v1.19+, unavailable in v1.22+; use apiregistration.k8s.io/v1 APIService apiservice.apiregistration.k8s.io/v1beta1.metrics.k8s.io created serviceaccount/metrics-server created deployment.apps/metrics-server created service/metrics-server created clusterrole.rbac.authorization.k8s.io/system:metrics-server created clusterrolebinding.rbac.authorization.k8s.io/system:metrics-server created
　　查看所有的命名空间  [root@k8scloude1 1.8+]# kubectl get ns NAME              STATUS   AGE default           Active   18h kube-node-lease   Active   18h kube-public       Active   18h kube-system       Active   18h
　　当观察到metrics-server-bcfb98c76-k5dmj状态为Running，metrics-server服务就正常启动了  [root@k8scloude1 1.8+]# kubectl get pod -n kube-system -o wide NAME                                       READY   STATUS    RESTARTS   AGE   IP                NODE         NOMINATED NODE   READINESS GATES calico-kube-controllers-6b9fbfff44-4jzkj   1/1     Running   2          19h   10.244.251.194    k8scloude3               calico-node-bdlgm                          1/1     Running   1          19h   192.168.110.130   k8scloude1               calico-node-hx8bk                          1/1     Running   1          19h   192.168.110.128   k8scloude3               calico-node-nsbfs                          1/1     Running   1          19h   192.168.110.129   k8scloude2               coredns-545d6fc579-7wm95                   1/1     Running   1          19h   10.244.158.68     k8scloude1               coredns-545d6fc579-87q8j                   1/1     Running   1          19h   10.244.158.67     k8scloude1               etcd-k8scloude1                            1/1     Running   1          19h   192.168.110.130   k8scloude1               kube-apiserver-k8scloude1                  1/1     Running   1          19h   192.168.110.130   k8scloude1               kube-controller-manager-k8scloude1         1/1     Running   1          19h   192.168.110.130   k8scloude1               kube-proxy-599xh                           1/1     Running   1          19h   192.168.110.128   k8scloude3               kube-proxy-lpj8z                           1/1     Running   1          19h   192.168.110.129   k8scloude2               kube-proxy-zxlk9                           1/1     Running   1          19h   192.168.110.130   k8scloude1               kube-scheduler-k8scloude1                  1/1     Running   1          19h   192.168.110.130   k8scloude1               metrics-server-bcfb98c76-k5dmj             1/1     Running   0          70s   10.244.112.131    k8scloude2              5.2 查看node负载
　　查看node的负载  [root@k8scloude1 1.8+]# kubectl top node  W0110 11:37:47.025099   75026 top_node.go:119] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag NAME         CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%    k8scloude1   257m         12%    1487Mi          45%        k8scloude2   104m         5%     698Mi           36%        k8scloude3   102m         5%     701Mi           36%5.3 查看pod负载
　　查看pod的负载
　　注释：一核心分成1000个微核心m 1核=1000m  [root@k8scloude1 1.8+]# kubectl top pods W0110 11:38:40.576780   75696 top_pod.go:140] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag No resources found in default namespace.  #-A表示所有命名空间 [root@k8scloude1 1.8+]# kubectl top pods -A W0110 11:38:47.276962   75784 top_pod.go:140] Using json format to get metrics. Next release will switch to protocol-buffers, switch early by passing --use-protocol-buffers flag NAMESPACE     NAME                                       CPU(cores)   MEMORY(bytes)    kube-system   calico-kube-controllers-6b9fbfff44-4jzkj   2m           25Mi             kube-system   calico-node-bdlgm                          37m          170Mi            kube-system   calico-node-hx8bk                          43m          157Mi            kube-system   calico-node-nsbfs                          56m          164Mi            kube-system   coredns-545d6fc579-7wm95                   3m           18Mi             kube-system   coredns-545d6fc579-87q8j                   3m           18Mi             kube-system   etcd-k8scloude1                            14m          91Mi             kube-system   kube-apiserver-k8scloude1                  60m          351Mi            kube-system   kube-controller-manager-k8scloude1         21m          56Mi             kube-system   kube-proxy-599xh                           1m           24Mi             kube-system   kube-proxy-lpj8z                           1m           24Mi             kube-system   kube-proxy-zxlk9                           1m           24Mi             kube-system   kube-scheduler-k8scloude1                  3m           23Mi             kube-system   metrics-server-bcfb98c76-k5dmj             1m           13Mi六.命名空间namespace的管理6.1 何为命名空间namespace
　　在 Kubernetes 中，命名空间（Namespace） 提供一种机制，将同一集群中的资源划分为相互隔离的组。 同一命名空间内的资源名称要唯一，但跨命名空间时没有这个要求。 命名空间作用域仅针对带有命名空间的对象，例如 Deployment、Service 等， 这种作用域对集群访问的对象不适用，例如 StorageClass、Node、PersistentVolume 等。  6.2 管理命名空间namespace
　　查看所有的命名空间  [root@k8scloude1 1.8+]# kubectl get namespaces  NAME              STATUS   AGE default           Active   19h kube-node-lease   Active   19h kube-public       Active   19h kube-system       Active   19h  [root@k8scloude1 1.8+]# kubectl get ns NAME              STATUS   AGE default           Active   19h kube-node-lease   Active   19h kube-public       Active   19h kube-system       Active   19h
　　创建命名空间，   注意：不同的namespace之间相互隔离  [root@k8scloude1 1.8+]# kubectl create ns ns1 namespace/ns1 created  [root@k8scloude1 1.8+]# kubectl create ns ns2 namespace/ns2 created  [root@k8scloude1 1.8+]# kubectl get ns NAME              STATUS   AGE default           Active   19h kube-node-lease   Active   19h kube-public       Active   19h kube-system       Active   19h ns1               Active   6s ns2               Active   4s
　　获取全局上下文，可以看到当前命名空间为default  [root@k8scloude1 ~]# kubectl config get-contexts  CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE *         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin   default
　　切换命名空间  #切换命名空间 [root@k8scloude1 ~]# kubectl config set-context --current --namespace=kube-system Context ＂kubernetes-admin@kubernetes＂ modified.  [root@k8scloude1 ~]# kubectl config get-contexts  CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE *         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin   kube-system  #获取当前K8S上下文 [root@k8scloude1 ~]# kubectl config current-context  kubernetes-admin@kubernetes6.2 使用kubens管理命名空间namespace
　　默认的切换命名空间的命令不好用，可以使用第三方的命名空间切换工具：   kubens   ，kubens命令所在的网站为： https://github.com/ahmetb/kubectx/releases/
　　下载kubens，并授予可执行权限  [root@k8scloude1 ~]# wget https://github.com/ahmetb/kubectx/releases/download/v0.9.4/kubens  [root@k8scloude1 ~]# ll -h kubens  -rw-r--r-- 1 root root 5.5K 12月  8 15:46 kubens  [root@k8scloude1 ~]# chmod +x kubens   [root@k8scloude1 ~]# mv kubens /bin/  [root@k8scloude1 ~]# ls /bin/kubens  /bin/kubens
　　查看所有的命名空间  [root@k8scloude1 ~]# kubens  default kube-node-lease kube-public kube-system ns1 ns2
　　切换namespace  #切换namespace到kube-system [root@k8scloude1 ~]# kubens kube-system Context ＂kubernetes-admin@kubernetes＂ modified. Active namespace is ＂kube-system＂.  #此时，默认查询的就是kube-system命名空间下的pod [root@k8scloude1 ~]# kubectl get pods -o wide NAME                                       READY   STATUS    RESTARTS   AGE   IP                NODE         NOMINATED NODE   READINESS GATES calico-kube-controllers-6b9fbfff44-4jzkj   1/1     Running   2          20h   10.244.251.194    k8scloude3               calico-node-bdlgm                          1/1     Running   1          20h   192.168.110.130   k8scloude1               calico-node-hx8bk                          1/1     Running   1          20h   192.168.110.128   k8scloude3               calico-node-nsbfs                          1/1     Running   1          20h   192.168.110.129   k8scloude2               coredns-545d6fc579-7wm95                   1/1     Running   1          20h   10.244.158.68     k8scloude1               coredns-545d6fc579-87q8j                   1/1     Running   1          20h   10.244.158.67     k8scloude1               etcd-k8scloude1                            1/1     Running   1          20h   192.168.110.130   k8scloude1               kube-apiserver-k8scloude1                  1/1     Running   1          20h   192.168.110.130   k8scloude1               kube-controller-manager-k8scloude1         1/1     Running   1          20h   192.168.110.130   k8scloude1               kube-proxy-599xh                           1/1     Running   1          20h   192.168.110.128   k8scloude3               kube-proxy-lpj8z                           1/1     Running   1          20h   192.168.110.129   k8scloude2               kube-proxy-zxlk9                           1/1     Running   1          20h   192.168.110.130   k8scloude1               kube-scheduler-k8scloude1                  1/1     Running   1          20h   192.168.110.130   k8scloude1               metrics-server-bcfb98c76-k5dmj             1/1     Running   0          56m   10.244.112.131    k8scloude2              
　　切换namespace到default  #切换namespace到default [root@k8scloude1 ~]# kubens default Context ＂kubernetes-admin@kubernetes＂ modified. Active namespace is ＂default＂.  #此时，默认查询的就是default命名空间下的pod [root@k8scloude1 ~]# kubectl get pods -o wide No resources found in default namespace.  #要查询kube-public命名空间下的pod，使用-n kube-public指定 [root@k8scloude1 ~]# kubectl get pods -n kube-public No resources found in kube-public namespace.