Kubernetes(k8s)安装过程详细记录

前言

本文对kubernetes的安装，以及集群部署过程进行记录和说明。

为了方便在离线环境中安装部署，后续内容中涉及的安装包及镜像，均为先下载，再安装。

环境规划

版本说明

软件	版本
操作系统	CentOS-7-x86_64-1810
Docker	19.03.8
Kubernetes	1.18.4

集群规划

Hostname	IP	安装组件
k8s-master	192.168.6.170	kubelet kube-apiserver kube-controller-manager kube-schedule kube-proxy
k8s-node-1	192.168.6.171	kubelet kube-proxy
k8s-node-2	192.168.6.172	kubelet kube-proxy

准备阶段

操作系统

以下准备工作需要在集群所有机器上进行配置。如果采用虚拟机进行集群组件，要注意每个虚拟机的MAC地址需要设置为不同的地址。

关闭防火墙

systemctl stop firewalld
systemctl disable firewalld

关闭selinux

修改/etc/selinux/config文件，将SELINUX修改为disabled。

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#     enforcing - SELinux security policy is enforced.
#     permissive - SELinux prints warnings instead of enforcing.
#     disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three values:
#     targeted - Targeted processes are protected,
#     minimum - Modification of targeted policy. Only selected processes are protected. 
#     mls - Multi Level Security protection.
SELINUXTYPE=targeted

关闭swap

sed -ri 's/.*swap.*/#&/' /etc/fstab

设置主机名称

根据集群规划，分别在各个主机上设置主机名。

hostnamectl set-hostname k8s-master
hostnamectl set-hostname k8s-node-1
hostnamectl set-hostname k8s-node-2

添加hosts

在/etc/hosts文件中追加以下内容：

192.168.6.170   k8s-master
192.168.6.171   k8s-node-1
192.168.6.172   k8s-node-2

修改内核参数

添加vi/etc/sysctl.d/k8s.conf配置，添加以下内容：

net.ipv4.ip_forward=1
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
vm.swappiness = 0

以上设置完成后，需要重启机器让设置生效。

rpm安装包

设置yum安装源

添加安装源配置文件/etc/yum.repos.d/kubernetes.repo，添加如下内容：

[kubernetes]
name=Kubernetes Repository
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=0

下载rpm安装包

yum install --downloadonly --downloaddir=./ -y kubeadm-1.18.3 --disableexcludes=kubernetes
yum install --downloadonly --downloaddir=./ -y kubelet-1.18.3 --disableexcludes=kubernetes
yum install --downloadonly --downloaddir=./ -y kubectl-1.18.3 --disableexcludes=kubernetes

执行yum install命令得到rpm安装包，得到与之相关的所有安装包，版本信息如下：

 kubeadm                   1.18.3-0   
 conntrack-tools           1.4.4-7.el7 
 cri-tools                 1.13.0-0       
 kubectl                   1.18.5-0       
 kubelet                   1.18.5-0          
 kubernetes-cni            0.8.6-0            
 libnetfilter_cthelper     1.0.0-11.el7       
 libnetfilter_cttimeout    1.0.0-7.el7        
 libnetfilter_queue        1.0.2-2.el7_2     
 socat                     1.7.3.2-2.el7    

安装rpm包

[root@localhost k8s]# rpm -ivh *.rpm
准备中...                          ################## [100%]
正在升级/安装...
   1:socat-1.7.3.2-2.el7              ################## [ 10%]
   2:libnetfilter_queue-1.0.2-2.el7_2 ################## [ 20%]
   3:libnetfilter_cttimeout-1.0.0-7.el################## [ 30%]
   4:libnetfilter_cthelper-1.0.0-11.el################## [ 40%]
   5:conntrack-tools-1.4.4-7.el7      ################## [ 50%]
   6:kubelet-1.18.3-0                 ################## [ 60%]
   7:kubernetes-cni-0.8.6-0           ################## [ 70%]
   8:kubectl-1.18.3-0                 ################## [ 80%]
   9:cri-tools-1.13.0-0               ################## [ 90%]
  10:kubeadm-1.18.3-0                 ################## [100%]

Docker

docker安装过程省略。

设置docker镜像源

设置国内docker镜像源，或者阿里的镜像源，加速镜像下载过程。

[root@localhost docker]# vi /etc/docker/daemon.json 
{
    "registry-mirrors": ["https://registry.docker-cn.com"]
}

列出所需镜像列表

[root@localhost v1.18.4]# kubeadm config images list
W0620 14:07:32.154847   14850 configset.go:202] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]
k8s.gcr.io/kube-apiserver:v1.18.4
k8s.gcr.io/kube-controller-manager:v1.18.4
k8s.gcr.io/kube-scheduler:v1.18.4
k8s.gcr.io/kube-proxy:v1.18.4
k8s.gcr.io/pause:3.2
k8s.gcr.io/etcd:3.4.3-0
k8s.gcr.io/coredns:1.6.7

由于k8s.gcr.io在国内无法访问，可通过国内阿里云仓库拉取镜像。
这里将kube*镜像版本改为1.18.3。

拉取镜像

docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.18.3  && \
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.18.3 && \
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.18.3 && \
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.18.3 && \
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.2 && \
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.3-0 && \
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.6.7

将下载后的镜像重新设置tag：

REPOSITORY                           TAG       IMAGE ID       SIZE
k8s.gcr.io/kube-proxy                v1.18.3   3439b7546f29   117MB
k8s.gcr.io/kube-apiserver            v1.18.3   7e28efa976bd   173MB
k8s.gcr.io/kube-controller-manager   v1.18.3   da26705ccb4b   162MB
k8s.gcr.io/kube-scheduler            v1.18.3   76216c34ed0c   95.3MB
k8s.gcr.io/pause                     3.2       80d28bedfe5d   683kB
k8s.gcr.io/coredns                   1.6.7     67da37a9a360   43.8MB
k8s.gcr.io/etcd                      3.4.3-0   303ce5db0e90   288MB

安装Kubernetes集群

我们使用官方提供的kubeadm工具进行k8s集群的创建及设置。

导出默认初始化配置文件

kubeadm config print init-defaults > init.default.yaml

修改初始化配置文件

W0703 10:50:00.528184   27266 configset.go:202] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]
[root@k8s-master k8s]# ls
images  init.default1.yaml  init.default.yaml  rpm
[root@k8s-master k8s]# vi init.default1.yaml 
apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 192.168.6.170
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: k8s-master
  taints:
  - effect: NoSchedule
    key: node-role.kubernetes.io/master
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: k8s.gcr.io
kind: ClusterConfiguration
kubernetesVersion: v1.18.3
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
scheduler: {}

advertiseAddress要改成主节点的物理IP，kubernetesVersion版本号改为实际安装的版本号。

初始化Master节点

kubeadm init --config=init.default.yaml

控制台输出如下：

W0703 10:46:38.413591   23954 configset.go:202] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]
[init] Using Kubernetes version: v1.18.3
[preflight] Running pre-flight checks
        [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[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'
[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] Starting the kubelet
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.6.170]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-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 [k8s-master localhost] and IPs [192.168.6.170 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.6.170 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
  ubeconfig] 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"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
W0703 10:46:45.105711   23954 manifests.go:225] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[control-plane] Creating static Pod manifest for "kube-scheduler"
W0703 10:46:45.106934   23954 manifests.go:225] the default kube-apiserver authorization-mode is "Node,RBAC"; using "Node,RBAC"
[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 18.505005 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.18" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node k8s-master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node k8s-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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
  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:
  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 192.168.6.170:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:3daaead0025c6c7097ceb6c66cd379f9fdae3d076dddb3a6c21d2df024146dac

设置KUBECONFIG环境变量

echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> ~/.bash_profile
或
export KUBECONFIG=/etc/kubernetes/admin.conf

添加Node节点

登录Node节点机器，执行以下命令：

kubeadm join 192.168.6.170:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:3daaead0025c6c7097ceb6c66cd379f9fdae3d076dddb3a6c21d2df024146dac

该命令来自Master节点执行kubeadm init输出的最后一部分提示。

此时，通过Master查看Node信息：

[root@k8s-master kubernetes]# kubectl get node -A
NAME         STATUS     ROLES    AGE     VERSION
k8s-master   NotReady   master   66m     v1.18.3
k8s-node-1   NotReady      2m51s   v1.18.3
k8s-node-2   NotReady      2m34s   v1.18.3

安装网络插件

下载calico配置：

curl https://docs.projectcalico.org/v3.14/manifests/calico.yaml -o calico.yaml

参考官网教程：
https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network

拉取镜像

docker pull calico/node:v3.14.1
docker pullcalico/pod2daemon-flexvol:v3.14.1
docker pullcalico/cni:v3.14.1
docker pull calico/kube-controllers:v3.14.1

在集群中所有机器上都进行拉取或导入。

创建calico网络

在Master上执行：

kubectl create -f calico.yaml

此时，查看节点状态已经是Ready状态了。

[root@k8s-master k8s]# kubectl get node -A
NAME         STATUS   ROLES    AGE     VERSION
k8s-master   Ready    master   5h50m   v1.18.3
k8s-node-1   Ready       4h46m   v1.18.3
k8s-node-2   Ready       4h46m   v1.18.3

检查Pod状态

网路插件创建完成后，可以查看pod状态已经为Running。

[root@k8s-master rpm]# kubectl get pods -A
NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE
kube-system   calico-kube-controllers-76d4774d89-5pk96   1/1     Running   0          26m
kube-system   calico-node-2qvhs                          1/1     Running   0          26m
kube-system   calico-node-hrd48                          1/1     Running   0          26m
kube-system   coredns-66bff467f8-2tkcb                   1/1     Running   0          72m
kube-system   coredns-66bff467f8-h2v5l                   1/1     Running   0          72m
kube-system   etcd-k8s-master                            1/1     Running   0          72m
kube-system   kube-apiserver-k8s-master                  1/1     Running   0          72m
kube-system   kube-controller-manager-k8s-master         1/1     Running   0          72m
kube-system   kube-proxy-jw7wv                           1/1     Running   0          72m
kube-system   kube-proxy-z2jqr                           1/1     Running   0          67m
kube-system   kube-scheduler-k8s-master                  1/1     Running   0          72m

集群状态：

[root@k8s-master rpm]# kubectl cluster-info
Kubernetes master is running at https://192.168.3.170:6443
KubeDNS is running at https://192.168.3.170:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

重置集群

如果需要还原通过kubeadm init创建的cluster，可以使用kubeadm reset命令进行重置，需要在Master和Node节点上执行。

安装kubectl命令自动补全

下载rpm包

yum install --downloadonly --downloaddir=./ -y bash-completion

安装

rpm -ivh bash-completion-2.1-8.el7.noarch.rpm

添加配置

source /usr/share/bash-completion/bash_completion
source <(kubectl completion bash)
echo "source <(kubectl completion bash)" >> ~/.bashrc

现在可以在命令行使用Tab键进行kubectl命令补全了。

结束

至此，kubernetes集群的创建过程就结束了。我们可以在K8S集群环境中部署我们应用进行研究和学习了。