一、概述
kubectl是Kubernetes集群的命令行工具，通过kubectl能够对集群本身进行管理，并能够在集群上进行容器化应用的安装和部署
二、命令格式
命令格式如下
kubectl [command] [type] [name] [flags]
参数
- command：指定要对资源执行的操作，例如create、get、describe、delete
- type：指定资源类型，资源类型是大小写敏感的，开发者能够以单数 、复数 和 缩略的形式
例如：
kubectl get pod pod1
kubectl get pods pod1
kubectl get po pod1
- name：指定资源的名称，名称也是大小写敏感的，如果省略名称，则会显示所有的资源，例如
kubectl get pods
- flags：指定可选的参数，例如，可用 -s 或者 -server参数指定Kubernetes API server的地址和端口
三、常见命令
kubectl help 获取更多信息
通过 help命令，能够获取帮助信息
# 获取kubectl的命令
kubectl --help
# 获取某个命令的介绍和使用
kubectl get --help
基础命令
常见的基础命令
| 命令 | 介绍 |
|---|---|
| create | 通过文件名或标准输入创建资源 |
| expose | 将一个资源公开为一个新的Service |
| run | 在集群中运行一个特定的镜像 |
| set | 在对象上设置特定的功能 |
| get | 显示一个或多个资源 |
| explain | 文档参考资料 |
| edit | 使用默认的编辑器编辑一个资源 |
| delete | 通过文件名，标准输入，资源名称或标签来删除资源 |
部署命令
| 命令 | 介绍 |
|---|---|
| rollout | 管理资源的发布 |
| rolling-update | 对给定的复制控制器滚动更新 |
| scale | 扩容或缩容Pod数量，Deployment、ReplicaSet、RC或Job |
| autoscale | 创建一个自动选择扩容或缩容并设置Pod数量 |
集群管理命令
| 命令 | 介绍 |
|---|---|
| certificate | 修改证书资源 |
| cluster-info | 显示集群信息 |
| top | 显示资源(CPU/M) |
| cordon | 标记节点不可调度 |
| uncordon | 标记节点可被调度 |
| drain | 驱逐节点上的应用，准备下线维护 |
| taint | 修改节点taint标记 |
故障和调试命令
| 命令 | 介绍 |
|---|---|
| describe | 显示特定资源或资源组的详细信息 |
| logs | 在一个Pod中打印一个容器日志，如果Pod只有一个容器，容器名称是可选的 |
| attach | 附加到一个运行的容器 |
| exec | 执行命令到容器 |
| port-forward | 转发一个或多个 |
| proxy | 运行一个proxy到Kubernetes API Server |
| cp | 拷贝文件或目录到容器中 |
| auth | 检查授权 |
其它命令
| 命令 | 介绍 |
|---|---|
| apply | 通过文件名或标准输入对资源应用配置 |
| patch | 使用补丁修改、更新资源的字段 |
| replace | 通过文件名或标准输入替换一个资源 |
| convert | 不同的API版本之间转换配置文件 |
| label | 更新资源上的标签 |
| annotate | 更新资源上的注释 |
| completion | 用于实现kubectl工具自动补全 |
| api-versions | 打印受支持的API版本 |
| config | 修改kubeconfig文件（用于访问API，比如配置认证信息） |
| help | 所有命令帮助 |
| plugin | 运行一个命令行插件 |
| version | 打印客户端和服务版本信息 |
目前使用的命令
# 创建一个nginx镜像
kubectl create deployment nginx --image=nginx
# 对外暴露端口
kubectl expose deployment nginx --port=80 --type=NodePort
# 查看资源
kubectl get pod, svc
# 对资源应用进行配置
kubectl apply -f四、helm3
helm 是基于 kubernetes 的包管理器。它之于 kubernetes 就如 yum 之于 centos，pip 之于 python，npm 之于 javascript
Helm 有两个重要得概念：chart 和 release
chart ：是创建一个应用的信息集合，包括各种 kubernetes 对象得配置模板、参数定义、依赖关系、文档说明等，可以将 chart 想象成 yum 中的软件安装包
release ：是 chart 的运行实例，代表了一个正在运行的应用。当 chart 被安装到 kubernetes 集群，就会生成一个 release，chart 能够多次安装到同一个集群，但是只会有一个 release
1、下载
wget https://get.helm.sh/helm-v3.2.0-linux-amd64.tar.gz
2、解压
tar -zxvf helm-v3.2.0-linux-amd64.tar.gz
3、拷贝
cp linux-amd64/helm /usr/local/bin
4、验证
[root@master ~]# helm version
version.BuildInfo{Version:"v3.2.0", GitCommit:"e11b7ce3b12db2941e90399e874513fbd24bcb71", GitTreeState:"clean", GoVersion:"go1.13.10"}
5、添加 chart 源
helm repo add stable https://kubernetes-charts.storage.googleapis.com
helm repo add aliyuncs https://apphub.aliyuncs.com
6、查询当前集群有哪些 chart 库
[root@master1 ~]# helm repo list
NAME URL
stable https://kubernetes-charts.storage.googleapis.com
aliyuncs https://apphub.aliyuncs.com
7、查询某个库 有哪些安装程序
[root@master1 ~]# helm search repo aliyuncs | head -5
NAME CHART VERSION APP VERSION DESCRIPTION
aliyuncs/admin-mongo 0.1.0 1 MongoDB管理工具(web gui)
aliyuncs/aerospike 0.3.2 v4.5.0.5 A Helm chart for Aerospike in Kubernetes
aliyuncs/airflow 4.3.3 1.10.9 Apache Airflow is a platform to programmaticall...
aliyuncs/ambassador 5.3.0 0.86.1 A Helm chart for Datawire Ambassador
8、查找安装程序
helm search repo nginx
9、安装一个程序
helm install nginx aliyuncs/nginx
10、查询 svc
[root@master1 ~]# kubectl get svc -n default
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 116m
nginx LoadBalancer 10.99.247.71 <pending> 80:30300/TCP,443:32617/TCP 45s
11、访问 集群
[root@master1 ~]# curl http://10.99.247.71
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
.......
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
12、查看安装的应用
[root@master1 ~]# helm list
NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION
nginx default 1 2020-12-15 11:48:13.181211885 +0800 CST deployed nginx-5.1.5 1.16.1
13、删除一个应用
helm uninstall nginx五、k8s安装kubernetes dashboard
1.修改后的recommended.yaml
# Copyright 2017 The Kubernetes Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
apiVersion: v1
kind: Namespace
metadata:
name: kubernetes-dashboard
---
apiVersion: v1
kind: ServiceAccount
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
type: NodePort
ports:
- port: 443
targetPort: 8443
nodePort: 31443
selector:
k8s-app: kubernetes-dashboard
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-certs
namespace: kubernetes-dashboard
type: Opaque
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-csrf
namespace: kubernetes-dashboard
type: Opaque
data:
csrf: ""
---
apiVersion: v1
kind: Secret
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-key-holder
namespace: kubernetes-dashboard
type: Opaque
---
kind: ConfigMap
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard-settings
namespace: kubernetes-dashboard
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
rules:
# Allow Dashboard to get, update and delete Dashboard exclusive secrets.
- apiGroups: [""]
resources: ["secrets"]
resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs", "kubernetes-dashboard-csrf"]
verbs: ["get", "update", "delete"]
# Allow Dashboard to get and update 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
resources: ["configmaps"]
resourceNames: ["kubernetes-dashboard-settings"]
verbs: ["get", "update"]
# Allow Dashboard to get metrics.
- apiGroups: [""]
resources: ["services"]
resourceNames: ["heapster", "dashboard-metrics-scraper"]
verbs: ["proxy"]
- apiGroups: [""]
resources: ["services/proxy"]
resourceNames: ["heapster", "http:heapster:", "https:heapster:", "dashboard-metrics-scraper", "http:dashboard-metrics-scraper"]
verbs: ["get"]
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
rules:
# Allow Metrics Scraper to get metrics from the Metrics server
- apiGroups: ["metrics.k8s.io"]
resources: ["pods", "nodes"]
verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: kubernetes-dashboard
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: kubernetes-dashboard
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: kubernetes-dashboard
subjects:
- kind: ServiceAccount
name: kubernetes-dashboard
namespace: kubernetes-dashboard
---
kind: Deployment
apiVersion: apps/v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
k8s-app: kubernetes-dashboard
template:
metadata:
labels:
k8s-app: kubernetes-dashboard
spec:
containers:
- name: kubernetes-dashboard
image: kubernetesui/dashboard:v2.1.0
imagePullPolicy: Always
ports:
- containerPort: 8443
protocol: TCP
args:
- --auto-generate-certificates
- --namespace=kubernetes-dashboard
# Uncomment the following line to manually specify Kubernetes API server Host
# If not specified, Dashboard will attempt to auto discover the API server and connect
# to it. Uncomment only if the default does not work.
# - --apiserver-host=http://my-address:port
volumeMounts:
- name: kubernetes-dashboard-certs
mountPath: /certs
# Create on-disk volume to store exec logs
- mountPath: /tmp
name: tmp-volume
livenessProbe:
httpGet:
scheme: HTTPS
path: /
port: 8443
initialDelaySeconds: 30
timeoutSeconds: 30
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsUser: 1001
runAsGroup: 2001
volumes:
- name: kubernetes-dashboard-certs
secret:
secretName: kubernetes-dashboard-certs
- name: tmp-volume
emptyDir: {}
serviceAccountName: kubernetes-dashboard
nodeSelector:
"kubernetes.io/os": linux
# Comment the following tolerations if Dashboard must not be deployed on master
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
---
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: dashboard-metrics-scraper
name: dashboard-metrics-scraper
namespace: kubernetes-dashboard
spec:
ports:
- port: 8000
targetPort: 8000
selector:
k8s-app: dashboard-metrics-scraper
---
kind: Deployment
apiVersion: apps/v1
metadata:
labels:
k8s-app: dashboard-metrics-scraper
name: dashboard-metrics-scraper
namespace: kubernetes-dashboard
spec:
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
k8s-app: dashboard-metrics-scraper
template:
metadata:
labels:
k8s-app: dashboard-metrics-scraper
annotations:
seccomp.security.alpha.kubernetes.io/pod: 'runtime/default'
spec:
containers:
- name: dashboard-metrics-scraper
image: kubernetesui/metrics-scraper:v1.0.6
ports:
- containerPort: 8000
protocol: TCP
livenessProbe:
httpGet:
scheme: HTTP
path: /
port: 8000
initialDelaySeconds: 30
timeoutSeconds: 30
volumeMounts:
- mountPath: /tmp
name: tmp-volume
securityContext:
allowPrivilegeEscalation: false
readOnlyRootFilesystem: true
runAsUser: 1001
runAsGroup: 2001
serviceAccountName: kubernetes-dashboard
nodeSelector:
"kubernetes.io/os": linux
# Comment the following tolerations if Dashboard must not be deployed on master
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
volumes:
- name: tmp-volume
emptyDir: {}
为了避免网络问题，其中第32行定义的Service需要进行修改，配置为NodePort，以便我们直接通过地址+端口进行访问，否则该service会被分配ClusterIP无法直接访问
其中nodePort:31443配置的31443端口，可以根据自己机器的环境选择一个未被占用的端口，然后我们将修改的文件上传到k8s集群的任何一个节点机器，执行以下命令即可：
kubectl apply -f recommended.yaml执行完成后，我们查看pods：
# kubectl apply -f recommended.yaml
执行完成后，我们查看pods：
[root@k8s ~]# kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-7f89b7bc75-5c6zv 1/1 Running 0 2d9h
kube-system coredns-7f89b7bc75-lbnxs 1/1 Running 0 2d9h
kube-system etcd-k8s.master001 1/1 Running 0 2d9h
kube-system kube-apiserver-k8s.master001 1/1 Running 0 2d9h
kube-system kube-controller-manager-k8s.master001 1/1 Running 0 2d9h
kube-system kube-flannel-ds-amd64-84ql2 1/1 Running 0 2d7h
kube-system kube-flannel-ds-amd64-qhbzl 1/1 Running 0 2d8h
kube-system kube-proxy-5856c 1/1 Running 0 2d9h
kube-system kube-proxy-dd9q4 1/1 Running 0 2d7h
kube-system kube-scheduler-k8s.master001 1/1 Running 0 2d9h
kubernetes-dashboard dashboard-metrics-scraper-79c5968bdc-qpwl7 1/1 Running 0 2d5h
kubernetes-dashboard kubernetes-dashboard-7448ffc97b-nv459 1/1 Running 1 2d5h
其中namespace为kubernetes-dashboard的两个pods为k8s dashboard。
如果查看了当前pods，发现其状态不是Running状态，可以通过以下命令查看pod启动时发生了什么问题：
[root@k8s ~]# kubectl describe pods -n kubernetes-dashboard kubernetes-dashboard-7448ffc97b-nv459
如果是镜像获取失败，可以从阿里云等国内镜像仓库下载之后，再执行kubectl apply -f recommended.yaml。
2.配置权限
2.1.访问dashboard
此时我们通过访问集群的任何节点的ip+31443端口来访问k8s dashboard（本文访问https://172.16.197.160:31443），可以看到如下页面：
因为k8s dashboard使用https进行访问，我们没有相关证书，因此Chrome或者Safari浏览器是禁止访问的，我们可以使用FireFox进行访问。
可以看到k8s提供两种登录机制，本文采用Token访问机制进行登录。
首先查看k8s集群的secret：
[root@k8s ~]# kubectl -n kubernetes-dashboard get secret
NAME TYPE DATA AGE
default-token-hm8n8 kubernetes.io/service-account-token 3 17h
kubernetes-dashboard-certs Opaque 0 17h
kubernetes-dashboard-csrf Opaque 1 17h
kubernetes-dashboard-key-holder Opaque 2 17h
kubernetes-dashboard-token-r7fpl kubernetes.io/service-account-token 3 17h
然后查看token：
[root@k8s ~]# kubectl describe secrets -n kubernetes-dashboard kubernetes-dashboard-token-r7fpl
Name: kubernetes-dashboard-token-r7fpl
Namespace: kubernetes-dashboard
Labels: <none>
Annotations: kubernetes.io/service-account.name: kubernetes-dashboard
kubernetes.io/service-account.uid: 1dbf2168-d42e-4557-b3ab-265888818975
Type: kubernetes.io/service-account-token
Data
====
ca.crt: 1066 bytes
namespace: 20 bytes
token: eyJhbGciOiJSUzI1NiIsImtpZCI6IjRhdzJQVS1fNExza2dYNXhBRDAxTTRRajAzUFV2SlFtTUZiUElqSjJERmsifQ.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.RSBZKHTpUPVDU6F2nsTid2eMclyODDmW6CrW5m7eJrcPgVOYh98zOYDd6OJyt7HG3n9ZyVzSXWFlMcQF25q3auXcQlPwjTeRpGoNNV2OhCrpNBaBmcOdq3LvSwj_l2ty3JRxvFPUQdTtDVLOvb431O-O_xZlnPHTR_bNK4SpY2BZh_UkPXqhh1boAmA0ORzbodFpAMfOx8Mk-_6QkOyhS0FAXfGE57kLSAYG2r9AqxMmQzLX7_IzvrR5FLVrivFrNYgYR9WB7EoD8QSeuYFnJZan9EwW2yTlWrDSLkSSd_tXfE23BqHd1naZt57IybdEj3nVl__xpGTvXHv7RDVV7A
复制最后的token字符串到登录界面，点击登录，可以看到dashboard首页：
此时我们看不到任何数据，点击右上角的小铃铛，发现异常信息：
serviceaccounts is forbidden: User “system:serviceaccount:kubernetes-dashboard:kubernetes-dashboard” cannot list resource “serviceaccounts” in API group “” in the namespace “default”，说明为权限不足，下面我们配置权限。
2.2.配置权限
k8s采用的是基于角色的访问控制策略，Role-Based Access Control, 即”RBAC”，使用”rbac.authorization.k8s.io” API Group实现授权决策，涉及到ServiceAccount，Role，ClusterRole，RoleBinding，ClusterRoleBinding，Secret等概念，后面的文章中我们会详细讲到。
首先解决本文的问题，执行以下命令：
[root@k8s ~]# kubectl create clusterrolebinding serviceaccount-cluster-admin --clusterrole=cluster-admin --user=system:serviceaccount:kubernetes-dashboard:kubernetes-dashboard
clusterrolebinding.rbac.authorization.k8s.io/serviceaccount-cluster-admin created
然后我们再看刚才访问的界面，已经刷新出数据：
此时，我们已经可以正常访问k8s dashboard。