之前基于kubeadm 搭建的单master双node 的k8s集群, 问题就是master 节点挂掉之后会导致整个集群不可用, 所以简单研究下多master的搭建方式。

1. 方案简介

k8s高可用集群_nginx


   用到的高可用技术主要是keepalived 和 haproxy。

1. keepalived

  Keepalived主要是通过虚拟路由冗余来实现高可用功能。

  Keepalived一个基于VRRP(Virtual Router Redundancy Protocol - 虚拟路由冗余协议) 协议来实现的 LVS 服务高可用方案,可以利用其来解决单点故障。一个LVS服务会有2台服务器运行Keepalived,一台为主服务器(MASTER),一台为备份服务器(BACKUP),但是对外表现为一个虚拟IP,主服务器会发送特定的消息给备份服务器,当备份服务器收不到这个消息的时候,即主服务器宕机的时候, 备份服务器就会接管虚拟IP,继续提供服务,从而保证了高可用性。

2. haproxy

  haproxy 类似于nginx, 是一个负载均衡、反向代理软件。 nginx 采用master-workers 进程模型,每个进程单线程,多核CPU能充分利用。 haproxy 是多线程,单进程就能实现高性能,虽然haproxy 也支持多进程。

2. 搭建集群

  基本上照着下面流程操作就可以了。

1. 安装要求

部署Kubernetes集群机器需要满足以下几个条件:

(1) 一台或多台机器,操作系统 CentOS7.x-86_x64

(2)硬件配置:2GB或更多RAM,2个CPU或更多CPU,硬盘30GB或更多

(3) 可以访问外网,需要拉取镜像,如果服务器不能上网,需要提前下载镜像并导入节点

(4) 禁止swap分区

2. 准备环境

k8s高可用集群_服务器_02

 接下来进行如下操作

# 关闭防火墙
systemctl stop firewalld
systemctl disable firewalld

# 关闭selinux
sed -i 's/enforcing/disabled/' /etc/selinux/config # 永久
setenforce 0 # 临时

# 关闭swap
swapoff -a # 临时
sed -ri 's/.*swap.*/#&/' /etc/fstab # 永久

# 根据规划设置主机名
hostnamectl set-hostname <hostname>

# 在master添加hosts
cat >> /etc/hosts << EOF
192.168.13.110 master.k8s.io k8s-vip
192.168.13.107 master01.k8s.io k8smaster01
192.168.13.108 master02.k8s.io k8smaster02
192.168.13.109 node01.k8s.io k8snode01
EOF

# 将桥接的IPv4流量传递到iptables的链
cat > /etc/sysctl.d/k8s.conf << EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system # 生效

# 时间同步
yum install ntpdate -y
ntpdate time.windows.com


3. 所有master 节点部署keepalived

1. 安装相关包和keepalived

yum install -y conntrack-tools libseccomp libtool-ltdl

yum install -y keepalived


2. 配置master 节点

k8smaster01

cat > /etc/keepalived/keepalived.conf <<EOF 
! Configuration File for keepalived

global_defs {
router_id k8s
}

vrrp_script check_haproxy {
script "killall -0 haproxy"
interval 3
weight -2
fall 10
rise 2
}

vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 51
priority 250
advert_int 1
authentication {
auth_type PASS
auth_pass ceb1b3ec013d66163d6ab
}
virtual_ipaddress {
192.168.13.110
}
track_script {
check_haproxy
}

}
EOF


k8smaster02

cat > /etc/keepalived/keepalived.conf <<EOF 
! Configuration File for keepalived

global_defs {
router_id k8s
}

vrrp_script check_haproxy {
script "killall -0 haproxy"
interval 3
weight -2
fall 10
rise 2
}

vrrp_instance VI_1 {
state BACKUP
interface ens33
virtual_router_id 51
priority 200
advert_int 1
authentication {
auth_type PASS
auth_pass ceb1b3ec013d66163d6ab
}
virtual_ipaddress {
192.168.13.110
}
track_script {
check_haproxy
}

}
EOF


3. 启动和检查

# 启动keepalived
systemctl start keepalived.service
# 设置开机启动
systemctl enable keepalived.service
# 查看启动状态
systemctl status keepalived.service


启动后查看master1的网卡信息: 可以看到有vip 相关的信息

ip a s ens33


4. 部署haproxy

1. 安装

yum install -y haproxy


2. 配置

两台master节点的配置均相同,配置中声明了后端代理的两个master节点服务器,指定了haproxy运行的端口为16443等,因此16443端口为集群的入口

cat > /etc/haproxy/haproxy.cfg << EOF
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
# to have these messages end up in /var/log/haproxy.log you will
# need to:
# 1) configure syslog to accept network log events. This is done
# by adding the '-r' option to the SYSLOGD_OPTIONS in
# /etc/sysconfig/syslog
# 2) configure local2 events to go to the /var/log/haproxy.log
# file. A line like the following can be added to
# /etc/sysconfig/syslog
#
# local2.* /var/log/haproxy.log
#
log 127.0.0.1 local2

chroot /var/lib/haproxy
pidfile /var/run/haproxy.pid
maxconn 4000
user haproxy
group haproxy
daemon

# turn on stats unix socket
stats socket /var/lib/haproxy/stats
#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
mode http
log global
option httplog
option dontlognull
option http-server-close
option forwardfor except 127.0.0.0/8
option redispatch
retries 3
timeout http-request 10s
timeout queue 1m
timeout connect 10s
timeout client 1m
timeout server 1m
timeout http-keep-alive 10s
timeout check 10s
maxconn 3000
#---------------------------------------------------------------------
# kubernetes apiserver frontend which proxys to the backends
#---------------------------------------------------------------------
frontend kubernetes-apiserver
mode tcp
bind *:16443
option tcplog
default_backend kubernetes-apiserver
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend kubernetes-apiserver
mode tcp
balance roundrobin
server master01.k8s.io 192.168.13.107:6443 check
server master02.k8s.io 192.168.13.108:6443 check
#---------------------------------------------------------------------
# collection haproxy statistics message
#---------------------------------------------------------------------
listen stats
bind *:1080
stats auth admin:awesomePassword
stats refresh 5s
stats realm HAProxy\ Statistics
stats uri /admin?stats
EOF


3. 启动和检查

两台master 都启动

# 设置开机启动
systemctl enable haproxy
# 开启haproxy
systemctl start haproxy
# 查看启动状态
systemctl status haproxy


检查端口

netstat -lntup|grep haproxy


5. 所有节点安装Docker/kubeadm/kubelet

Kubernetes默认CRI(容器运行时)为Docker,因此先安装Docker。

1. 安装docker

wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
yum -y install docker-ce-18.06.1.ce-3.el7
systemctl enable docker && systemctl start docker
docker --version


修改docker 镜像源:

cat > /etc/docker/daemon.json << EOF
{
"registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"]
}
EOF


2. 添加阿里云YUM软件源

cat > /etc/yum.repos.d/kubernetes.repo << EOF
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF


3. 安装kubeadm,kubelet和kubectl

yum install -y kubelet-1.21.3 kubeadm-1.21.3 kubectl-1.21.3
systemctl enable kubelet


6. 部署k8smaster

1. 创建kubeadm 配置文件

在具有vip的master上操作,这里为master1

mkdir /usr/local/kubernetes/manifests -p

cd /usr/local/kubernetes/manifests/

vi kubeadm-config.yaml

apiServer:
certSANs:
- k8smaster01
- k8smaster02
- master.k8s.io
- 192.168.13.110
- 192.168.13.107
- 192.168.13.108
- 127.0.0.1
extraArgs:
authorization-mode: Node,RBAC
timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta1
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controlPlaneEndpoint: "master.k8s.io:16443"
controllerManager: {}
dns:
type: CoreDNS
etcd:
local:
dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: v1.21.3
networking:
dnsDomain: cluster.local
podSubnet: 10.244.0.0/16
serviceSubnet: 10.1.0.0/16
scheduler: {}


2. 在k8smaster01 节点执行

kubeadm init --config kubeadm-config.yaml


执行后提示如下:

[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

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

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 control-plane nodes by copying certificate authorities
and service account keys on each node and then running the following as root:

kubeadm join master.k8s.io:16443 --token piealo.bck99wdpdv14rlo6 \
--discovery-token-ca-cert-hash sha256:e0579b642a2b62219627f9f19af5227dadb539f9db11992585644d4f126046e5 \
--control-plane

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join master.k8s.io:16443 --token piealo.bck99wdpdv14rlo6 \
--discovery-token-ca-cert-hash sha256:e0579b642a2b62219627f9f19af5227dadb539f9db11992585644d4f126046e5


按照提示配置环境变量,使用kubectl工具:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config


检查:

[root@k8smaster01 manifests]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8smaster01 NotReady control-plane,master 144m v1.21.3
[root@k8smaster01 manifests]# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-59d64cd4d4-62bhq 0/1 Pending 0 144m
coredns-59d64cd4d4-95dl5 0/1 Pending 0 144m
etcd-k8smaster01 1/1 Running 0 144m
kube-apiserver-k8smaster01 1/1 Running 0 144m
kube-controller-manager-k8smaster01 1/1 Running 0 144m
kube-proxy-df8c8 1/1 Running 0 144m
kube-scheduler-k8smaster01 1/1 Running 0 145m


3. 安装集群网络

mkdir flannel
cd flannel
wget -c https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml


创建以及查看:

kubectl apply -f kube-flannel.yml 
kubectl get pods -n kube-system


4. k8smaster02 加入节点

(1)复制密钥及相关文件

从master1复制密钥及相关文件到master2

ssh root@192.168.13.108 mkdir -p /etc/kubernetes/pki/etcd

scp /etc/kubernetes/admin.conf root@192.168.13.108:/etc/kubernetes

scp /etc/kubernetes/pki/{ca.*,sa.*,front-proxy-ca.*} root@192.168.13.108:/etc/kubernetes/pki

scp /etc/kubernetes/pki/etcd/ca.* root@192.168.13.108:/etc/kubernetes/pki/etcd


(2) master2加入集群

在k8smaster02 执行在k8smaster01上init后输出的join命令,需要带上参数 `--control-plane` 表示把master控制节点加入集群

kubeadm join master.k8s.io:16443 --token piealo.bck99wdpdv14rlo6 \
--discovery-token-ca-cert-hash sha256:e0579b642a2b62219627f9f19af5227dadb539f9db11992585644d4f126046e5 --control-plane


执行完后输出:

This node has joined the cluster and a new control plane instance was created:

* Certificate signing request was sent to apiserver and approval was received.
* The Kubelet was informed of the new secure connection details.
* Control plane (master) label and taint were applied to the new node.
* The Kubernetes control plane instances scaled up.
* A new etcd member was added to the local/stacked etcd cluster.

To start administering your cluster from this node, 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


然后执行上面输出的信息:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config


检查状态:

[root@k8smaster02 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
k8smaster01 Ready control-plane,master 17h v1.21.3
k8smaster02 NotReady control-plane,master 6m21s v1.21.3
[root@k8smaster02 ~]# kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-59d64cd4d4-62bhq 1/1 Running 0 17h
kube-system coredns-59d64cd4d4-95dl5 1/1 Running 0 17h
kube-system etcd-k8smaster01 1/1 Running 0 17h
kube-system etcd-k8smaster02 1/1 Running 0 6m22s
kube-system kube-apiserver-k8smaster01 1/1 Running 0 17h
kube-system kube-apiserver-k8smaster02 1/1 Running 0 6m25s
kube-system kube-controller-manager-k8smaster01 1/1 Running 1 17h
kube-system kube-controller-manager-k8smaster02 1/1 Running 0 6m26s
kube-system kube-flannel-ds-p2std 1/1 Running 0 15h
kube-system kube-flannel-ds-vc2w2 0/1 Init:ImagePullBackOff 0 6m27s
kube-system kube-proxy-df8c8 1/1 Running 0 17h
kube-system kube-proxy-nx8dg 1/1 Running 0 6m27s
kube-system kube-scheduler-k8smaster01 1/1 Running 1 17h
kube-system kube-scheduler-k8smaster02 1/1 Running 0 6m26s


3. k8snode01 加入集群

(1) 在k8snode01 节点上执行之前输出的信息:

kubeadm join master.k8s.io:16443 --token piealo.bck99wdpdv14rlo6 \
--discovery-token-ca-cert-hash sha256:e0579b642a2b62219627f9f19af5227dadb539f9db11992585644d4f126046e5


执行完后输出如下:

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.


(2) 在master 节点查看

[root@k8smaster01 manifests]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8smaster01 Ready control-plane,master 17h v1.21.3
k8smaster02 NotReady control-plane,master 11m v1.21.3
k8snode01 NotReady <none> 2m26s v1.21.3


(3) 重新安装网络

[root@k8smaster01 flannel]# pwd
/root/flannel
[root@k8smaster01 flannel]# kubectl apply -f kube-flannel.yml


(4) 再次查看集群状态

[root@k8smaster01 flannel]# kubectl cluster-info
Kubernetes control plane is running at https://master.k8s.io:16443
CoreDNS is running at https://master.k8s.io:16443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
[root@k8smaster01 flannel]# kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8smaster01 Ready control-plane,master 18h v1.21.3 192.168.13.107 <none> CentOS Linux 7 (Core) 3.10.0-1160.49.1.el7.x86_64 docker://18.6.1
k8smaster02 Ready control-plane,master 38m v1.21.3 192.168.13.108 <none> CentOS Linux 7 (Core) 3.10.0-1160.49.1.el7.x86_64 docker://18.6.1
k8snode01 Ready <none> 28m v1.21.3 192.168.13.109 <none> CentOS Linux 7 (Core) 3.10.0-1160.49.1.el7.x86_64 docker://18.6.1


4. 测试集群

[root@k8smaster01 flannel]# kubectl create deployment nginx --image=nginx
deployment.apps/nginx created
[root@k8smaster01 flannel]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-6799fc88d8-g7vcg 0/1 ContainerCreating 0 11s <none> k8snode01 <none> <none>
[root@k8smaster01 flannel]# kubectl expose deployment nginx --port=80 --type=NodePort
service/nginx exposed
[root@k8smaster01 flannel]# kubectl get pod,svc
NAME READY STATUS RESTARTS AGE
pod/nginx-6799fc88d8-g7vcg 1/1 Running 0 98s

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.1.0.1 <none> 443/TCP 18h
service/nginx NodePort 10.1.49.27 <none> 80:32367/TCP 60s


  然后从外部查看任意一个节点的32367 端口即可查看到nginx。 107、08、09、110 四个ip都可以访问到。



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