写在前面

本章是kubernetes系列教程第二篇,要深入学习kubernetes,首先需要有一个k8s环境,然而,受制硬件环境,网络环境等因素,要搭建一个环境有一定的困难,让很多初学者望而却步,本章主要介绍通过kubeadm安装工具部署kubernetes集群,考虑到国内网络限制,已将安装镜像通过跳板机下载到本地,方便大家离线安装。

1. MiniKube快速部署环境

1.1 安装概述

要学习kubernetes,首先需要有一个kubernetes集群,社区为了满足不同场景下,提供了不同的安装方法以适应各种场景需求,常见方法有:

  • MiniKube,是一个将kubernetes单节点安装在本地虚拟化工具,MiniKube安装文档
  • 二进制安装,通过已编译好的二进制文件安装,需设置参数,可定制化强,安装难度大
  • Kubeadm,一个自动化安装工具,以镜像的方式部署,使用简单,镜像在谷歌仓库,下载易失败

对于学习环境,Katacoda提供了一个在线的MiniKube环境,只需在控制台启用即可使用,当然也可以将MiniKube下载到本地使用。对于生产环境,推荐使用二进制安装或者Kubeadm,新版kubeadm目前已将kubernetes管理组件以pod的形式部署在集群中,不管用哪种方式,受限于GFW,大部分镜像下载,大家自行补脑和解决,本文以离线的方式安装部署,根据安装版本下载对应的安装镜像倒入系统即可。

1.2 MiniKube在线环境

Katacoda使用MiniKube提供了一个在线部署kubernetres环境,当然也可以基于MiniKube本地安装,如果是初学者想初探一下kubernetes的功能,可以使用Katacoda提供的线上环境,达到快速入门学习的目的。参考文档,直接在Hello MiniKube文档中点击Open terminal即可自动创建一个kubernetes环境,其会自动拉取镜像并部署所需环境。

MiniKube在线安装环境

如上图所示,MiniKube的提供的优点如下:

  • 快捷,自动部署环境
  • 无需占用本地资源
  • 适用于学习环境

2 kubeadm部署k8s集群

kubeadm安装部署集群

2.1 环境说明和准备

【软件版本】

软件名软件版本
OSCentOS Linux release 7.6.1810 (Core)
Dockerdocker-ce-18.03.1.ce-1.el7
Kubernetes1.14.1
Kubeadmkubeadm-1.14.1-0.x86_64
etcd3.3.10
flannelv0.11.0

【环境说明】

三台机器均为腾讯云上购买的CVM(Cloud Virtual Machine),机器配置是2vcpu+4G memory+50G disk

主机名角色IP地址软件
node-1master10.254.100.101docker,kubelet,etcd,kube-apiserver,kube-controller-manager,kube-scheduler
node-2worker10.254.100.102docker,kubelet,kube-proxy,flannel
node-3worker10.254.100.103docker,kubelet,kube-proxy,flannel

【环境准备】

1、设置主机名,其他两个节点类似设置

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root@VM_100_101_centos ~# hostnamectl set-hostname node-1
root@VM_100_101_centos ~# hostname
node-1

2、设置hosts文件,其他两个节点设置相同内容

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root@node-1 ~# vim /etc/hosts
127.0.0.1 localhost localhost.localdomain 
10.254.100.101 node-1
10.254.100.102 node-2
10.254.100.103 node-3

3、设置SSH无密码登录,并通过ssh-copy-id将公钥拷贝到对端

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#生成密钥对
root@node-1 .ssh# ssh-keygen -P ''
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:zultDMEL8bZmpbUjQahVjthVAcEkN929w5EkUmPkOrU root@node-1
The key's randomart image is:
+---RSA 2048----+
|      .=O=+=o.. |
|     o+o..+.o+  |
|    .oo=.   o. o |
|    . . * oo .+  |
|       oSOo.E  . |
|       oO.o.     |
|       o++ .     |
|       . .o      |
|        ...      |
+----SHA256-----+

#拷贝公钥到node-2和node-3节点
root@node-1 .ssh# ssh-copy-id -i /root/.ssh/id_rsa.pub node-2:
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host 'node-1 (10.254.100.101)' can't be established.
ECDSA key fingerprint is SHA256:jLUH0exgyJdsy0frw9R+FiWy+0o54LgB6dgVdfc6SEE.
ECDSA key fingerprint is MD5:f4:86:a8:0e:a6:03:fc:a6:04:df:91:d8:7a:a7:0d:9e.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@node-1's password: 
Number of key(s) added: 1
Now try logging into the machine, with:   "ssh 'node-2'"
and check to make sure that only the key(s) you wanted were added.

4、关闭防火墙和SElinux

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[root@node-1 ~]# systemctl stop firewalld
[root@node-1 ~]# systemctl disable firewalld
[root@node-1 ~]# sed -i '/^SELINUX=/ s/enforcing/disabled/g' /etc/selinux/config 
[root@node-1 ~]# setenforce 0

2.2 安装Docker环境

1、下载docker的yum源

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[root@node-1 ~]# cd /etc/yum.repos.d/
[root@node-1 ~]# wget https://download.docker.com/linux/centos/docker-ce.repo

2、设置cgroup driver类型为systemd

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[root@node-1 ~]# cat > /etc/docker/daemon.json <<EOF
> {
>  "exec-opts": ["native.cgroupdriver=systemd"],
>  "log-driver": "json-file",
>  "log-opts": {
>  "max-size": "100m"
>  },
>  "storage-driver": "overlay2",
>  "storage-opts": [
>  "overlay2.override_kernel_check=true"
>  ]
> }
> EOF

3、启动docker服务并验证,可以通过docker info查看docker安装的版本等信息

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[root@node-1 ~]# systemctl restart docker
[root@node-1 ~]# systemctl enable docker

备注:如果机器不具备上网条件,或者访问docker的yum源仓库很慢,我已将docker相关rpm包依赖包下载到腾讯云cos中,下载链接,可以下载到本地,然后解压缩然后运行yum localinstall进行安装。

2.3 安装kubeadm组件

1、安装kubernetes源,国内可以使用阿里的kubernetes源,速度会快一点

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[root@node-1 ~]#cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

2、安装kubeadm,kubelet,kubectl,会自动安装几个重要依赖包:socat,cri-tools,cni等包

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[root@node-1 ~]# yum install kubeadm-1.14.1-0 kubectl-1.14.1-0 kubelet-1.14.1-0 --disableexcludes=kubernetes -y

3、设置iptables网桥参数

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[root@node-1 ~]# cat <<EOF >  /etc/sysctl.d/k8s.conf
> net.bridge.bridge-nf-call-ip6tables = 1
> net.bridge.bridge-nf-call-iptables = 1
> EOF

[root@node-1 ~]# sysctl --system,然后使用sysctl -a|grep 参数的方式验证是否生效

4、重新启动kubelet服务,使配置生效

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[root@node-1 ~]# systemctl restart kubelet
[root@node-1 ~]# systemctl enable kubelet

备注:如果本地下载很慢或者无法下载kubernetes中yum源rpm包,可以通过离线方式下载,下载路径

2.4 导入kubernetes镜像

1、从cos中下载kubernetes安装镜像,并通过docker load命令将镜像导入到环境中

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[root@node-1 v1.14.1]# docker image load -i etcd:3.3.10.tar 
[root@node-1 v1.14.1]# docker image load -i pause:3.1.tar 
[root@node-1 v1.14.1]# docker image load -i coredns:1.3.1.tar 
[root@node-1 v1.14.1]# docker image load -i flannel:v0.11.0-amd64.tar 
[root@node-1 v1.14.1]# docker image load -i kube-apiserver:v1.14.1.tar 
[root@node-1 v1.14.1]# docker image load -i kube-controller-manager:v1.14.1.tar 
[root@node-1 v1.14.1]# docker image load -i kube-scheduler:v1.14.1.tar 
[root@node-1 v1.14.1]# docker image load -i kube-proxy:v1.14.1.tar 

2、检查镜像列表

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[root@node-1 v1.14.1]# docker image list
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/kube-proxy                v1.14.1             20a2d7035165        3 months ago        82.1MB
k8s.gcr.io/kube-apiserver            v1.14.1             cfaa4ad74c37        3 months ago        210MB
k8s.gcr.io/kube-scheduler            v1.14.1             8931473d5bdb        3 months ago        81.6MB
k8s.gcr.io/kube-controller-manager   v1.14.1             efb3887b411d        3 months ago        158MB
quay.io/coreos/flannel               v0.11.0-amd64       ff281650a721        6 months ago        52.6MB
k8s.gcr.io/coredns                   1.3.1               eb516548c180        6 months ago        40.3MB
k8s.gcr.io/etcd                      3.3.10              2c4adeb21b4f        8 months ago        258MB
k8s.gcr.io/pause                     3.1                 da86e6ba6ca1        19 months ago       742kB

2.5 kubeadm初始化集群

kubeadm初始化集群

1、 kubeadm初始化集群,需要设置初始参数

  • –pod-network-cidr指定pod使用的网段,设置值根据不同的网络plugin选择,本文以flannel为例设置值为10.244.0.0/16
  • container runtime可以通过–cri-socket指定socket文件所属路径
  • 如果有多个网卡可以通过–apiserver-advertise-address指定master地址,默认会选择访问外网的ip
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[root@node-1 ~]# kubeadm init --apiserver-advertise-address 10.254.100.101 --apiserver-bind-port 6443 --kubernetes-version 1.14.1 --pod-network-cidr 10.244.0.0/16
[init] Using Kubernetes version: v1.14.1
[preflight] Running pre-flight checks
 [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 18.03.1-ce. Latest validated version: 18.09
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'#下载镜像
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"#生成CA等证书
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [node-1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.254.100.101]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [node-1 localhost] and IPs [10.254.100.101 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [node-1 localhost] and IPs [10.254.100.101 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"#生成master节点静态pod配置文件
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 18.012370 seconds
[upload-config] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.14" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --experimental-upload-certs
[mark-control-plane] Marking the node node-1 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node node-1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: r8n5f2.9mic7opmrwjakled
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles#配置RBAC授权
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
Your Kubernetes control-plane has initialized successfully!
To start using your cluster, you need to run the following as a regular user:
 mkdir -p $HOME/.kube #配置环境变量配置文件
 sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
 sudo chown $(id -u):$(id -g) $HOME/.kube/config
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at: #安装网络插件
 https://kubernetes.io/docs/concepts/cluster-administration/addons/
Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 10.254.100.101:6443 --token r8n5f2.9mic7opmrwjakled \ #添加节点命令优先记录下来
 --discovery-token-ca-cert-hash sha256:16e383c8abff6233021331944080087f0514ddd15d96c65d19443b0af02d64ab 

通过kubeadm init –apiserver-advertise-address 10.254.100.101 –apiserver-bind-port 6443 –kubernetes-version 1.14.1 –pod-network-cidr 10.244.0.0/16安装命令,显示了kubeadm安装过程中的一些重要步骤:下载镜像,生成证书,生成配置文件,配置RBAC授权认证,配置环境变量,安装网络插件指引,添加node指引配置文件。

2、生成kubectl环境配置文件

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[root@node-1 ~]# mkdir /root/.kube
[root@node-1 ~]# cp -i /etc/kubernetes/admin.conf /root/.kube/config
[root@node-1 ~]# kubectl get nodes
NAME  STATUS  ROLES AGE  VERSION
node-1  NotReady  master  6m29s  v1.14.1

3、添加node节点,将另外两个节点加入到集群中,复制上述的添加节点命令到指定节点添加即可。

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[root@node-3 ~]# kubeadm join 10.254.100.101:6443 --token r8n5f2.9mic7opmrwjakled \
>     --discovery-token-ca-cert-hash sha256:16e383c8abff6233021331944080087f0514ddd15d96c65d19443b0af02d64ab 
[preflight] Running pre-flight checks
	[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 18.03.1-ce. Latest validated version: 18.09
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.14" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Activating the kubelet service
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

以此类推到node-2节点添加即可添加完之后通过kubectl get nodes验证此时由于还没有安装网络plugin
所有的node节点均显示NotReady状态
[root@node-1 ~]# kubectl get nodes
NAME     STATUS     ROLES    AGE     VERSION
node-1   NotReady   master   16m     v1.14.1
node-2   NotReady   <none>   4m34s   v1.14.1
node-3   NotReady   <none>   2m10s   v1.14.1

kubeadm join添加节点

4、安装网络plugin,kubernetes支持多种类型网络插件,要求网络支持CNI插件即可,CNI是Container Network Interface,要求kubernetes的中pod网络访问方式:

  • node和node之间网络互通
  • pod和pod之间网络互通
  • node和pod之间网络互通

不同的CNI plugin支持的特性有所差别。kubernetes支持多种开源的网络CNI插件,常见的有flannel、calico、canal、weave等,flannel是一种overlay的网络模型,通过vxlan隧道方式构建tunnel网络,实现k8s中网络的互联,后续在做介绍,如下是安装过程:

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[root@node-1 ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/62e44c867a2846fefb68bd5f178daf4da3095ccb/Documentation/kube-flannel.yml
podsecuritypolicy.extensions/psp.flannel.unprivileged created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

5、通过上述输出可知道,部署flannel 需要RBAC授权,配置configmap和daemonset,其中Daemonset能够适配各种类型的CPU架构,默认安装了多个,一般是adm64即可,可以将上述的url下载编辑,保留kube-flannel-ds-amd64这个daemonset即可,或者将其删除

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#查看flannel安装的daemonsets
[root@node-1 ~]# kubectl get daemonsets -n kube-system 
NAME                      DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR                     AGE
kube-flannel-ds-amd64     3         3         3       3            3           beta.kubernetes.io/arch=amd64     2m34s
kube-flannel-ds-arm       0         0         0       0            0           beta.kubernetes.io/arch=arm       2m34s
kube-flannel-ds-arm64     0         0         0       0            0           beta.kubernetes.io/arch=arm64     2m34s
kube-flannel-ds-ppc64le   0         0         0       0            0           beta.kubernetes.io/arch=ppc64le   2m34s
kube-flannel-ds-s390x     0         0         0       0            0           beta.kubernetes.io/arch=s390x     2m34s
kube-proxy                3         3         3       3            3           <none>                            30m

#删除不需要的damonsets
[root@node-1 ~]# kubectl delete daemonsets kube-flannel-ds-arm kube-flannel-ds-arm64 kube-flannel-ds-ppc64le kube-flannel-ds-s390x -n kube-system
daemonset.extensions "kube-flannel-ds-arm" deleted
daemonset.extensions "kube-flannel-ds-arm64" deleted
daemonset.extensions "kube-flannel-ds-ppc64le" deleted
daemonset.extensions "kube-flannel-ds-s390x" deleted

6、此时再验证node的安装情况,所有节点均已显示为Ready状态,安装完毕!

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[root@node-1 ~]# kubectl get nodes
NAME     STATUS   ROLES    AGE   VERSION
node-1   Ready    master   29m   v1.14.1
node-2   Ready    <none>   17m   v1.14.1
node-3   Ready    <none>   15m   v1.14.1

2.6 验证kubernetes组件

1、验证node状态,获取当前安装节点,可以查看到状态, 角色,启动市场,版本,

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[root@node-1 ~]# kubectl get nodes 
NAME     STATUS   ROLES    AGE   VERSION
node-1   Ready    master   46m   v1.14.1
node-2   Ready    <none>   34m   v1.14.1
node-3   Ready    <none>   32m   v1.14.1

2、查看kubernetse服务组件状态,包括scheduler,controller-manager,etcd

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[root@node-1 ~]# kubectl get componentstatuses 
NAME  STATUS MESSAGE  ERROR
scheduler Healthy  ok  
controller-manager  Healthy  ok  
etcd-0  Healthy  {"health":"true"}  

3、查看pod的情况,master中的角色包括kube-apiserver,kube-scheduler,kube-controller-manager,etcd,coredns以pods形式部署在集群中,worker节点的kube-proxy也以pod的形式部署。实际上pod是以其他控制器如daemonset的形式控制的。

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[root@node-1 ~]# kubectl get pods -n kube-system 
NAME  READY  STATUS RESTARTS  AGE
coredns-fb8b8dccf-hrqm8 1/1  Running  0 50m
coredns-fb8b8dccf-qwwks 1/1  Running  0 50m
etcd-node-1 1/1  Running  0 48m
kube-apiserver-node-1 1/1  Running  0 49m
kube-controller-manager-node-1  1/1  Running  0 49m
kube-proxy-lfckv  1/1  Running  0 38m
kube-proxy-x5t6r  1/1  Running  0 50m
kube-proxy-x8zqh  1/1  Running  0 36m
kube-scheduler-node-1 1/1  Running  0 49m

2.7 配置kubectl命令补全

使用kubectl和kubernetes交互时候可以使用缩写模式也可以使用完整模式,如kubectl get nodes和kubectl get no能实现一样的效果,为了提高工作效率,可以使用命令补全的方式加快工作效率。

1、生成kubectl bash命令行补全shell

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[root@node-1 ~]# kubectl completion bash >/etc/kubernetes/kubectl.sh
[root@node-1 ~]# echo "source /etc/kubernetes/kubectl.sh" >>/root/.bashrc 
[root@node-1 ~]# cat /root/.bashrc 
# .bashrc

# User specific aliases and functions

alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'

# Source global definitions
if [ -f /etc/bashrc ]; then
	. /etc/bashrc
fi
source /etc/kubernetes/kubectl.sh #添加环境变量配置

2、加载shell环境变量,使配置生效

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[root@node-1 ~]# source /etc/kubernetes/kubectl.sh 

3、校验命令行补全,命令行中输入kubectl get co再按TAB键就能自动补全了

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[root@node-1~]# kubectl get co componentstatuses configmaps  controllerrevisions.apps   
[root@node-1~]# kubectl get componentstatuses 

除了支持命令行补全之外,kubectl还支持命令简写,如下是一些常见的命令行检测操作,更多通过kubectl api-resources命令获取,SHORTNAMES显示的是子命令中的简短用法。

  • kubectl get componentstatuses,简写kubectl get cs获取组件状态
  • kubectl get nodes,简写kubectl get no获取node节点列表
  • kubectl get services,简写kubectl get svc获取服务列表
  • kubectl get deployments,简写kubectl get deploy获取deployment列表
  • kubectl get statefulsets,简写kubectl get sts获取有状态服务列表

参考文档

  1. Container Runtime安装文档:https://kubernetes.io/docs/setup/production-environment/container-runtimes/
  2. kubeadm安装:https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/
  3. 初始化kubeadm集群:https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network

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