1. 简介
Kubernetes v1.13版本发布后，kubeadm才正式进入GA，可以生产使用,用kubeadm部署kubernetes集群也是以后的发展趋势。目前Kubernetes的对应镜像仓库，在国内阿里云也有了镜像站点，使用kubeadm部署Kubernetes集群变得简单并且容易了很多，本文使用kubeadm带领大家快速部署Kubernetes v1.13.2版本。
注意：请不要把目光仅仅放在部署上，如果你是新手，推荐先熟悉用二进制文件部署后，再来学习用kubeadm部署。二进制文件部署请查看我博客的其他文章。
2. 架构信息
系统版本：CentOS 7.6 内核：3.10.0-957.el7.x86_64 Kubernetes: v1.13.2 Docker-ce: 18.06 推荐硬件配置：2核2G Keepalived保证apiserever服务器的IP高可用 Haproxy实现apiserver的负载均衡 为了减少服务器数量，haproxy、keepalived配置在node-01和node-02。
| 节点名称 | 角色 | IP | 安装软件 |
|---|---|---|---|
| 负载VIP | VIP | 10.31.90.200 | |
| node-01 | master | 10.31.90.201 | kubeadm、kubelet、kubectl、docker、haproxy、keepalived |
| node-02 | master | 10.31.90.202 | kubeadm、kubelet、kubectl、docker、haproxy、keepalived |
| node-03 | master | 10.31.90.203 | kubeadm、kubelet、kubectl、docker |
| node-04 | node | 10.31.90.204 | kubeadm、kubelet、kubectl、docker |
| node-05 | node | 10.31.90.205 | kubeadm、kubelet、kubectl、docker |
| node-06 | node | 10.31.90.206 | kubeadm、kubelet、kubectl、docker |
| service网段 | 10.245.0.0/16 |
2.部署前准备工作
1) 关闭selinux和防火墙
sed -ri 's#(SELINUX=).*#\1disabled#' /etc/selinux/config setenforce 0 systemctl disable firewalld systemctl stop firewalld 2) 关闭swap
swapoff -a 3) 为每台服务器添加host解析记录
cat >>/etc/hosts<<EOF 10.31.90.201 node-01 10.31.90.202 node-02 10.31.90.203 node-03 10.31.90.204 node-04 10.31.90.205 node-05 10.31.90.206 node-06 EOF 4) 创建并分发密钥
在node-01创建ssh密钥。
[root@node-01 ~]# ssh-keygen -t rsa Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): Created directory '/root/.ssh'. Enter passphrase (empty for no passphrase): Enter same passphrase again: 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: SHA256:26z6DcUarn7wP70dqOZA28td+K/erv7NlaJPLVE1BTA root@node-01 The key's randomart image is: +---[RSA 2048]----+ | E..o+| | . o| | . | | . . | | S o . | | .o X oo .| | oB +.o+oo.| | .o*o+++o+o| | .++o+Bo+=B*B| +----[SHA256]-----+ 分发node-01的公钥，用于免密登录其他服务器
for n in `seq -w 01 06`;do ssh-copy-id node-$n;done 5) 配置内核参数
cat <<EOF > /etc/sysctl.d/k8s.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 net.ipv4.ip_nonlocal_bind = 1 net.ipv4.ip_forward = 1 vm.swappiness=0 EOF sysctl --system 6) 加载ipvs模块
cat > /etc/sysconfig/modules/ipvs.modules <<EOF #!/bin/bash modprobe -- ip_vs modprobe -- ip_vs_rr modprobe -- ip_vs_wrr modprobe -- ip_vs_sh modprobe -- nf_conntrack_ipv4 EOF chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4 7) 添加yum源
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 wget http://mirrors.aliyun.com/repo/Centos-7.repo -O /etc/yum.repos.d/CentOS-Base.repo wget http://mirrors.aliyun.com/repo/epel-7.repo -O /etc/yum.repos.d/epel.repo wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo 2. 部署keepalived和haproxy
1) 安装keepalived和haproxy
在node-01和node-02安装keepalived和haproxy
yum install -y keepalived haproxy 2) 修改配置
keepalived配置
node-01的priority为100，node-02的priority为90，其他配置一样。
[root@node-01 ~]# cat /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email { feng110498@163.com } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_1 } vrrp_instance VI_1 { state MASTER interface eth0 lvs_sync_daemon_inteface eth0 virtual_router_id 88 advert_int 1 priority 100 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.31.90.200/24 } } haproxy配置
node-01和node-02的haproxy配置是一样的。此处我们监听的是10.31.90.200的8443端口，因为haproxy是和k8s apiserver是部署在同一台服务器上，都用6443会冲突。
global chroot /var/lib/haproxy daemon group haproxy user haproxy log 127.0.0.1:514 local0 warning pidfile /var/lib/haproxy.pid maxconn 20000 spread-checks 3 nbproc 8 defaults log global mode tcp retries 3 option redispatch listen https-apiserver bind 10.31.90.200:8443 mode tcp balance roundrobin timeout server 900s timeout connect 15s server apiserver01 10.31.90.201:6443 check port 6443 inter 5000 fall 5 server apiserver02 10.31.90.202:6443 check port 6443 inter 5000 fall 5 server apiserver03 10.31.90.203:6443 check port 6443 inter 5000 fall 5 3) 启动服务
systemctl enable keepalived && systemctl start keepalived systemctl enable haproxy && systemctl start haproxy 3. 部署kubernetes
1) 安装软件
由于kubeadm对Docker的版本是有要求的，需要安装与kubeadm匹配的版本。 由于版本更新频繁，请指定对应的版本号，本文采用1.13.2版本，其它版本未经测试。
yum install -y kubelet-1.13.2 kubeadm-1.13.2 kubectl-1.13.2 ipvsadm ipset docker-ce-18.06.1.ce #启动docker systemctl enable docker && systemctl start docker #设置kubelet开机自启动 systemctl enable kubelet 2) 修改初始化配置
使用kubeadm config print init-defaults > kubeadm-init.yaml 打印出默认配置，然后在根据自己的环境修改配置.
[root@node-01 ~]# cat kubeadm-init.yaml apiVersion: kubeadm.k8s.io/v1beta1 bootstrapTokens: - groups: - system:bootstrappers:kubeadm:default-node-token token: abcdef.0123456789abcdef ttl: 24h0m0s usages: - signing - authentication kind: InitConfiguration localAPIEndpoint: advertiseAddress: 10.31.90.201 bindPort: 6443 nodeRegistration: criSocket: /var/run/dockershim.sock name: node-01 taints: - effect: NoSchedule key: node-role.kubernetes.io/master --- apiVersion: kubeadm.k8s.io/v1beta1 kind: ClusterConfiguration apiServer: timeoutForControlPlane: 4m0s certificatesDir: /etc/kubernetes/pki clusterName: kubernetes controlPlaneEndpoint: "10.31.90.200:8443" dns: type: CoreDNS etcd: local: dataDir: /var/lib/etcd imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers kubernetesVersion: v1.13.2 networking: dnsDomain: cluster.local podSubnet: "" serviceSubnet: "10.245.0.0/16" scheduler: {} controllerManager: {} --- apiVersion: kubeproxy.config.k8s.io/v1alpha1 kind: KubeProxyConfiguration mode: "ipvs" 3) 预下载镜像
[root@node-01 ~]# kubeadm config images pull --config kubeadm-init.yaml [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.13.2 [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.13.2 [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.13.2 [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.13.2 [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.1 [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.2.24 [config/images] Pulled registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.2.6 4) 初始化
[root@node-01 ~]# kubeadm init --config kubeadm-init.yaml [init] Using Kubernetes version: v1.13.2 [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 "ca" certificate and key [certs] Generating "apiserver" certificate and key [certs] apiserver serving cert is signed for DNS names [node-01 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.12.0.1 10.31.90.201 10.31.90.200] [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-01 localhost] and IPs [10.31.90.201 127.0.0.1 ::1] [certs] Generating "etcd/peer" certificate and key [certs] etcd/peer serving cert is signed for DNS names [node-01 localhost] and IPs [10.31.90.201 127.0.0.1 ::1] [certs] Generating "etcd/healthcheck-client" certificate and key [certs] Generating "apiserver-etcd-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" [endpoint] WARNING: port specified in controlPlaneEndpoint overrides bindPort in the controlplane address [kubeconfig] Writing "admin.conf" kubeconfig file [endpoint] WARNING: port specified in controlPlaneEndpoint overrides bindPort in the controlplane address [kubeconfig] Writing "kubelet.conf" kubeconfig file [endpoint] WARNING: port specified in controlPlaneEndpoint overrides bindPort in the controlplane address [kubeconfig] Writing "controller-manager.conf" kubeconfig file [endpoint] WARNING: port specified in controlPlaneEndpoint overrides bindPort in the controlplane address [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 22.503955 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 "node-01" as an annotation [mark-control-plane] Marking the node node-01 as control-plane by adding the label "node-role.kubernetes.io/master=''" [mark-control-plane] Marking the node node-01 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 [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 [endpoint] WARNING: port specified in controlPlaneEndpoint overrides bindPort in the controlplane address [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 10.31.90.200:8443 --token abcdef.0123456789abcdef --discovery-token-ca-cert-hash sha256:84201a329ec4388263e97303c6e4de50c2de2aa157a3b961cb8a6f325fadedb1 kubeadm init主要执行了以下操作：
-
[init]：指定版本进行初始化操作
-
[preflight] ：初始化前的检查和下载所需要的Docker镜像文件
-
[kubelet-start] ：生成kubelet的配置文件”/var/lib/kubelet/config.yaml”，没有这个文件kubelet无法启动，所以初始化之前的kubelet实际上启动失败。
-
[certificates]：生成Kubernetes使用的证书，存放在/etc/kubernetes/pki目录中。
-
[kubeconfig] ：生成 KubeConfig 文件，存放在/etc/kubernetes目录中，组件之间通信需要使用对应文件。
-
[control-plane]：使用/etc/kubernetes/manifest目录下的YAML文件，安装 Master 组件。
-
[etcd]：使用/etc/kubernetes/manifest/etcd.yaml安装Etcd服务。
-
[wait-control-plane]：等待control-plan部署的Master组件启动。
-
[apiclient]：检查Master组件服务状态。
-
[uploadconfig]：更新配置
-
[kubelet]：使用configMap配置kubelet。
-
[patchnode]：更新CNI信息到Node上，通过注释的方式记录。
-
[mark-control-plane]：为当前节点打标签，打了角色Master，和不可调度标签，这样默认就不会使用Master节点来运行Pod。
-
[bootstrap-token]：生成token记录下来，后边使用kubeadm join往集群中添加节点时会用到
-
[addons]：安装附加组件CoreDNS和kube-proxy
5) 为kubectl准备Kubeconfig文件
kubectl默认会在执行的用户家目录下面的.kube目录下寻找config文件。这里是将在初始化时[kubeconfig]步骤生成的admin.conf拷贝到.kube/config。
[root@node-01 ~]# mkdir -p $HOME/.kube [root@node-01 ~]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config [root@node-01 ~]# chown $(id -u):$(id -g)$HOME/.kube/config 在该配置文件中，记录了API Server的访问地址，所以后面直接执行kubectl命令就可以正常连接到API Server中。
6) 查看组件状态
[root@node-01 ~]# kubectl get cs NAME STATUS MESSAGE ERROR scheduler Healthy ok controller-manager Healthy ok etcd-0 Healthy {"health": "true"} [root@node-01 ~]# kubectl get node NAME STATUS ROLES AGE VERSION node-01 NotReady master 14m v1.13.2 目前只有一个节点，角色是Master，状态是NotReady。
7) 其他master部署
在node-01将证书文件拷贝至其他master节点
USER=root CONTROL_PLANE_IPS="node-02 node-03" for host in ${CONTROL_PLANE_IPS}; do ssh "${USER}"@$host "mkdir -p /etc/kubernetes/pki/etcd" scp /etc/kubernetes/pki/ca.* "${USER}"@$host:/etc/kubernetes/pki/ scp /etc/kubernetes/pki/sa.* "${USER}"@$host:/etc/kubernetes/pki/ scp /etc/kubernetes/pki/front-proxy-ca.* "${USER}"@$host:/etc/kubernetes/pki/ scp /etc/kubernetes/pki/etcd/ca.* "${USER}"@$host:/etc/kubernetes/pki/etcd/ scp /etc/kubernetes/admin.conf "${USER}"@$host:/etc/kubernetes/ done 在其他master执行,注意--experimental-control-plane参数
kubeadm join 10.31.90.200:8443 --token abcdef.0123456789abcdef --discovery-token-ca-cert-hash sha256:84201a329ec4388263e97303c6e4de50c2de2aa157a3b961cb8a6f325fadedb1 --experimental-control-plane 注意：token有效期是有限的，如果旧的token过期，可以使用
kubeadm token create --print-join-command重新创建一条token。
8) node部署
在node-04、node-05、node-06执行,注意没有--experimental-control-plane参数
kubeadm join 10.31.90.200:8443 --token abcdef.0123456789abcdef --discovery-token-ca-cert-hash sha256:84201a329ec4388263e97303c6e4de50c2de2aa157a3b961cb8a6f325fadedb1 9) 部署网络插件flannel
Master节点NotReady的原因就是因为没有使用任何的网络插件，此时Node和Master的连接还不正常。目前最流行的Kubernetes网络插件有Flannel、Calico、Canal、Weave这里选择使用flannel。
[root@node-01 ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml 10) 查看节点状态
所有的节点已经处于Ready状态。
[root@node-01 ~]# kubectl get node NAME STATUS ROLES AGE VERSION node-01 Ready master 35m v1.13.2 node-02 Ready master 36m v1.13.2 node-03 Ready master 36m v1.13.2 node-04 Ready <none> 40m v1.13.2 node-05 Ready <none> 40m v1.13.2 node-06 Ready <none> 40m v1.13.2 查看pod
[root@node-01 ~]# kubectl get pod -n kube-system NAME READY STATUS RESTARTS AGE coredns-89cc84847-j8mmg 1/1 Running 0 1d coredns-89cc84847-rbjxs 1/1 Running 0 1d etcd-node-01 1/1 Running 1 1d etcd-node-02 1/1 Running 0 1d etcd-node-03 1/1 Running 0 1d kube-apiserver-node-01 1/1 Running 0 1d kube-apiserver-node-02 1/1 Running 0 1d kube-apiserver-node-03 1/1 Running 0 1d kube-controller-manager-node-01 1/1 Running 2 1d kube-controller-manager-node-02 1/1 Running 0 1d kube-controller-manager-node-03 1/1 Running 0 1d kube-proxy-jfbmv 1/1 Running 0 1d kube-proxy-lvkms 1/1 Running 0 1d kube-proxy-qx7kh 1/1 Running 0 1d kube-proxy-xst5v 1/1 Running 0 1d kube-proxy-zfwrk 1/1 Running 0 1d kube-proxy-ztg6j 1/1 Running 0 1d kube-scheduler-node-01 1/1 Running 1 1d kube-scheduler-node-02 1/1 Running 1 1d kube-scheduler-node-03 1/1 Running 1 1d kube-flannel-ds-amd64-87wzj 1/1 Running 0 1d kube-flannel-ds-amd64-lczwm 1/1 Running 0 1d kube-flannel-ds-amd64-lwc2j 1/1 Running 0 1d kube-flannel-ds-amd64-mwlfq 1/1 Running 0 1d kube-flannel-ds-amd64-nj2mk 1/1 Running 0 1d kube-flannel-ds-amd64-wx7vd 1/1 Running 0 1d 查看ipvs的状态
[root@node-01 ~]# ipvsadm -L -n IP Virtual Server version 1.2.1 (size=4096) Prot LocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 10.245.0.1:443 rr -> 10.31.90.201:6443 Masq 1 2 0 -> 10.31.90.202:6443 Masq 1 0 0 -> 10.31.90.203:6443 Masq 1 2 0 TCP 10.245.0.10:53 rr -> 10.32.0.3:53 Masq 1 0 0 -> 10.32.0.4:53 Masq 1 0 0 TCP 10.245.90.161:80 rr -> 10.45.0.1:80 Masq 1 0 0 TCP 10.245.90.161:443 rr -> 10.45.0.1:443 Masq 1 0 0 TCP 10.245.149.227:1 rr -> 10.31.90.204:1 Masq 1 0 0 -> 10.31.90.205:1 Masq 1 0 0 -> 10.31.90.206:1 Masq 1 0 0 TCP 10.245.181.126:80 rr -> 10.34.0.2:80 Masq 1 0 0 -> 10.45.0.0:80 Masq 1 0 0 -> 10.46.0.0:80 Masq 1 0 0 UDP 10.245.0.10:53 rr -> 10.32.0.3:53 Masq 1 0 0 -> 10.32.0.4:53 Masq 1 0 0 至此kubernetes集群部署完成。如有问题欢迎在下面留言交流。希望大家多多关注和点赞，谢谢！