概 述
Kubernetes集群的搭建方法其实有多种，比如我在之前的文章《利用K8S技术栈打造个人私有云（连载之：K8S集群搭建）》中使用的就是二进制的安装方法。虽然这种方法有利于我们理解 k8s集群，但却过于繁琐。而 kubeadm是 Kubernetes官方提供的用于快速部署Kubernetes集群的工具，其历经发展如今已经比较成熟了，利用其来部署 Kubernetes集群可以说是非常好上手，操作起来也简便了许多，因此本文详细叙述之。
节点规划
本文准备部署一个 一主两从 的 三节点 Kubernetes集群，整体节点规划如下表所示：
| 主机名 | IP | 角色 |
|---|---|---|
| k8s-master | 192.168.39.79 | k8s主节点 |
| k8s-node-1 | 192.168.39.77 | k8s从节点 |
| k8s-node-2 | 192.168.39.78 | k8s从节点 |
下面介绍一下各个节点的软件版本：
- 操作系统：
CentOS-7.4-64Bit - Docker版本：
1.13.1 - Kubernetes版本：
1.13.1
所有节点都需要安装以下组件：
Docker：不用多说了吧kubelet：运行于所有 Node上，负责启动容器和 Podkubeadm：负责初始化集群kubectl： k8s命令行工具，通过其可以部署/管理应用 以及CRUD各种资源
准备工作
- 所有节点关闭防火墙
systemctl disable firewalld.service
systemctl stop firewalld.service
- 禁用SELINUX
setenforce 0
vi /etc/selinux/config
SELINUX=disabled
- 所有节点关闭 swap
swapoff -a
- 设置所有节点主机名
hostnamectl --static set-hostname k8s-master
hostnamectl --static set-hostname k8s-node-1
hostnamectl --static set-hostname k8s-node-2
- 所有节点 主机名/IP加入 hosts解析
编辑 /etc/hosts文件，加入以下内容：
192.168.39.79 k8s-master
192.168.39.77 k8s-node-1
192.168.39.78 k8s-node-2
组件安装
0x01. Docker安装（所有节点）
不赘述 ! ! !
0x02. kubelet、kubeadm、kubectl安装（所有节点）
- 首先准备repo
cat>>/etc/yum.repos.d/kubrenetes.repo<<EOF
[kubernetes]
name=Kubernetes Repo
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
EOF
- 然后执行如下指令来进行安装
setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX= disabled/' /etc/selinux/config
yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet
Master节点配置
0x01. 初始化 k8s集群
为了应对网络不畅通的问题，我们国内网络环境只能提前手动下载相关镜像并重新打 tag :
docker pull mirrorgooglecontainers/kube-apiserver:v1.13.1
docker pull mirrorgooglecontainers/kube-controller-manager:v1.13.1
docker pull mirrorgooglecontainers/kube-scheduler:v1.13.1
docker pull mirrorgooglecontainers/kube-proxy:v1.13.1
docker pull mirrorgooglecontainers/pause:3.1
docker pull mirrorgooglecontainers/etcd:3.2.24
docker pull coredns/coredns:1.2.6
docker pull registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64
docker tag mirrorgooglecontainers/kube-apiserver:v1.13.1 k8s.gcr.io/kube-apiserver:v1.13.1
docker tag mirrorgooglecontainers/kube-controller-manager:v1.13.1 k8s.gcr.io/kube-controller-manager:v1.13.1
docker tag mirrorgooglecontainers/kube-scheduler:v1.13.1 k8s.gcr.io/kube-scheduler:v1.13.1
docker tag mirrorgooglecontainers/kube-proxy:v1.13.1 k8s.gcr.io/kube-proxy:v1.13.1
docker tag mirrorgooglecontainers/pause:3.1 k8s.gcr.io/pause:3.1
docker tag mirrorgooglecontainers/etcd:3.2.24 k8s.gcr.io/etcd:3.2.24
docker tag coredns/coredns:1.2.6 k8s.gcr.io/coredns:1.2.6
docker tag registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64
docker rmi mirrorgooglecontainers/kube-apiserver:v1.13.1
docker rmi mirrorgooglecontainers/kube-controller-manager:v1.13.1
docker rmi mirrorgooglecontainers/kube-scheduler:v1.13.1
docker rmi mirrorgooglecontainers/kube-proxy:v1.13.1
docker rmi mirrorgooglecontainers/pause:3.1
docker rmi mirrorgooglecontainers/etcd:3.2.24
docker rmi coredns/coredns:1.2.6
docker rmi registry.cn-shenzhen.aliyuncs.com/cp_m/flannel:v0.10.0-amd64
然后再在 Master节点上执行如下命令初始化 k8s集群：
kubeadm init --kubernetes-version=v1.13.1 --apiserver-advertise-address 192.168.39.79 --pod-network-cidr=10.244.0.0/16
--kubernetes-version: 用于指定 k8s版本--apiserver-advertise-address：用于指定使用 Master的哪个network interface进行通信，若不指定，则 kubeadm会自动选择具有默认网关的 interface--pod-network-cidr：用于指定Pod的网络范围。该参数使用依赖于使用的网络方案，本文将使用经典的flannel网络方案。
执行命令后，控制台给出了如下所示的详细集群初始化过程：
[root@localhost ~]# kubeadm init --config kubeadm-config.yaml
W1224 11:01:25.408209 10137 strict.go:54] error unmarshaling configuration schema.GroupVersionKind{Group:"kubeadm.k8s.io", Version:"v1beta1", Kind:"ClusterConfiguration"}: error unmarshaling JSON: while decoding JSON: json: unknown field "\u00a0 podSubnet”
[init] Using Kubernetes version: v1.13.1
[preflight] Running pre-flight checks
[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] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki”
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [localhost.localdomain localhost] and IPs [192.168.39.79 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [localhost.localdomain localhost] and IPs [192.168.39.79 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [localhost.localdomain kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.39.79]
[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”
[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 24.005638 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system” Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.13" in namespace kube-system with the configuration for the kubelets in the cluster
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "localhost.localdomain" as an annotation
[mark-control-plane] Marking the node localhost.localdomain as control-plane by adding the label "node-role.kubernetes.io/master=''”
[mark-control-plane] Marking the node localhost.localdomain as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 26uprk.t7vpbwxojest0tvq
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public” namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
Your Kubernetes master 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/
You can now join any number of machines by running the following on each node
as root:
kubeadm join 192.168.39.79:6443 --token 26uprk.t7vpbwxojest0tvq --discovery-token-ca-cert-hash sha256:028727c0c21f22dd29d119b080dcbebb37f5545e7da1968800140ffe225b0123
[root@localhost ~]#
0x02. 配置 kubectl
在 Master上用 root用户执行下列命令来配置 kubectl：
echo "export KUBECONFIG=/etc/kubernetes/admin.conf" >> /etc/profile
source /etc/profile
echo $KUBECONFIG
0x03. 安装Pod网络
安装 Pod网络是 Pod之间进行通信的必要条件，k8s支持众多网络方案，这里我们依然选用经典的 flannel方案
- 首先设置系统参数：
sysctl net.bridge.bridge-nf-call-iptables=1
- 然后在 Master节点上执行如下命令：
kubectl apply -f kube-flannel.yaml
kube-flannel.yaml文件在此
一旦 Pod网络安装完成，可以执行如下命令检查一下 CoreDNS Pod此刻是否正常运行起来了，一旦其正常运行起来，则可以继续后续步骤
kubectl get pods --all-namespaces -o wide
同时我们可以看到主节点已经就绪：kubectl get nodes
添加 Slave节点
在两个 Slave节点上分别执行如下命令来让其加入Master上已经就绪了的 k8s集群：
kubeadm join --token <token> <master-ip>:<master-port> --discovery-token-ca-cert-hash sha256:<hash>
如果 token忘记，则可以去 Master上执行如下命令来获取：
kubeadm token list
上述kubectl join命令的执行结果如下：
[root@localhost ~]# kubeadm join 192.168.39.79:6443 --token yndddp.oamgloerxuune80q --discovery-token-ca-cert-hash sha256:7a45c40b5302aba7d8b9cbd3afc6d25c6bb8536dd6317aebcd2909b0427677c8
[preflight] Running pre-flight checks
[discovery] Trying to connect to API Server "192.168.39.79:6443”
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.39.79:6443”
[discovery] Requesting info from "https://192.168.39.79:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "192.168.39.79:6443”
[discovery] Successfully established connection with API Server "192.168.39.79:6443”
[join] Reading configuration from the cluster…
[join] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml’
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.13" 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
[tlsbootstrap] Waiting for the kubelet to perform the TLS Bootstrap…
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "localhost.localdomain" as an annotation
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 master to see this node join the cluster.
效果验证
- 查看节点状态
kubectl get nodes
- 查看所有 Pod状态
kubectl get pods --all-namespaces -o wide
好了，集群现在已经正常运行了，接下来看看如何正常的拆卸集群。
拆卸集群
首先处理各节点：
kubectl drain <node name> --delete-local-data --force --ignore-daemonsets
kubectl delete node <node name>
一旦节点移除之后，则可以执行如下命令来重置集群：
kubeadm reset
安装 dashboard
就像给elasticsearch配一个可视化的管理工具一样，我们最好也给 k8s集群配一个可视化的管理工具，便于管理集群。
因此我们接下来安装 v1.10.0版本的 kubernetes-dashboard，用于集群可视化的管理。
- 首先手动下载镜像并重新打标签：（所有节点）
docker pull registry.cn-qingdao.aliyuncs.com/wangxiaoke/kubernetes-dashboard-amd64:v1.10.0
docker tag registry.cn-qingdao.aliyuncs.com/wangxiaoke/kubernetes-dashboard-amd64:v1.10.0 k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.0
docker image rm registry.cn-qingdao.aliyuncs.com/wangxiaoke/kubernetes-dashboard-amd64:v1.10.0
- 安装 dashboard：
kubectl create -f dashboard.yaml
dashboard.yaml 文件在此
- 查看 dashboard的 pod是否正常启动，如果正常说明安装成功:
kubectl get pods --namespace=kube-system
[root@k8s-master ~]# kubectl get pods --namespace=kube-system
NAME READY STATUS RESTARTS AGE
coredns-86c58d9df4-4rds2 1/1 Running 0 81m
coredns-86c58d9df4-rhtgq 1/1 Running 0 81m
etcd-k8s-master 1/1 Running 0 80m
kube-apiserver-k8s-master 1/1 Running 0 80m
kube-controller-manager-k8s-master 1/1 Running 0 80m
kube-flannel-ds-amd64-8qzpx 1/1 Running 0 78m
kube-flannel-ds-amd64-jvp59 1/1 Running 0 77m
kube-flannel-ds-amd64-wztbk 1/1 Running 0 78m
kube-proxy-crr7k 1/1 Running 0 81m
kube-proxy-gk5vf 1/1 Running 0 78m
kube-proxy-ktr27 1/1 Running 0 77m
kube-scheduler-k8s-master 1/1 Running 0 80m
kubernetes-dashboard-79ff88449c-v2jnc 1/1 Running 0 21s
- 查看 dashboard的外网暴露端口
kubectl get service --namespace=kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP 5h38m
kubernetes-dashboard NodePort 10.99.242.186 <none> 443:31234/TCP 14
- 生成私钥和证书签名：
openssl genrsa -des3 -passout pass:x -out dashboard.pass.key 2048
openssl rsa -passin pass:x -in dashboard.pass.key -out dashboard.key
rm dashboard.pass.key
openssl req -new -key dashboard.key -out dashboard.csr【如遇输入，一路回车即可】
- 生成SSL证书：
openssl x509 -req -sha256 -days 365 -in dashboard.csr -signkey dashboard.key -out dashboard.crt
- 然后将生成的
dashboard.key和dashboard.crt置于路径/home/share/certs下，该路径会配置到下面即将要操作的
dashboard-user-role.yaml文件中
- 创建 dashboard用户
kubectl create -f dashboard-user-role.yaml
dashboard-user-role.yaml 文件在此
- 获取登陆token
kubectl describe secret/$(kubectl get secret -nkube-system |grep admin|awk '{print $1}') -nkube-system
[root@k8s-master ~]# kubectl describe secret/$(kubectl get secret -nkube-system |grep admin|awk '{print $1}') -nkube-system
Name: admin-token-9d4vl
Namespace: kube-system
Labels: <none>
Annotations: kubernetes.io/service-account.name: admin
kubernetes.io/service-account.uid: a320b00f-07ed-11e9-93f2-000c2978f207
Type: kubernetes.io/service-account-token
Data
====
ca.crt: 1025 bytes
namespace: 11 bytes
token: eyJhbGciOiJSUzI1NiIsImtpZCI6IiJ9.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJrdWJlLXN5c3RlbSIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VjcmV0Lm5hbWUiOiJhZG1pbi10b2tlbi05ZDR2bCIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VydmljZS1hY2NvdW50Lm5hbWUiOiJhZG1pbiIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VydmljZS1hY2NvdW50LnVpZCI6ImEzMjBiMDBmLTA3ZWQtMTFlOS05M2YyLTAwMGMyOTc4ZjIwNyIsInN1YiI6InN5c3RlbTpzZXJ2aWNlYWNjb3VudDprdWJlLXN5c3RlbTphZG1pbiJ9.WbaHx-BfZEd0SvJwA9V_vGUe8jPMUHjKlkT7MWJ4JcQldRFY8Tdpv5GKCY25JsvT_GM3ob303r0yE6vjQdKna7EfQNO_Wb2j1Yu5UvZnWw52HhNudHNOVL_fFRKxkSVjAILA_C_HvW6aw6TG5h7zHARgl71I0LpW1VESeHeThipQ-pkt-Dr1jWcpPgE39cwxSgi-5qY4ssbyYBc2aPYLsqJibmE-KUhwmyOheF4Lxpg7E3SQEczsig2HjXpNtJizCu0kPyiR4qbbsusulH-kdgjhmD9_XWP9k0BzgutXWteV8Iqe4-uuRGHZAxgutCvaL5qENv4OAlaArlZqSgkNWw
token既然生成成功，接下来就可以打开浏览器，输入 token来登录进集群管理页面：
后 记
由于能力有限，若有错误或者不当之处，还请大家批评指正，一起学习交流！
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