centos7使用kubeadm配置高可用k8s集群

原文链接： https://juejin.im/post/5b460ec1e51d45195866c935

简介

使用kubeadm配置多master节点，实现高可用。

安装

实验环境说明

实验架构图

lab1: etcd master haproxy keepalived 11.11.11.111
lab2: etcd master haproxy keepalived 11.11.11.112
lab3: etcd master haproxy keepalived 11.11.11.113
lab4: node  11.11.11.114
lab5: node  11.11.11.115
lab6: node  11.11.11.116

vip(loadblancer ip): 11.11.11.110
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实验使用的Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :

ENV["LC_ALL"] = "en_US.UTF-8"

Vagrant.configure("2") do |config|
    (1..6).each do |i|
      config.vm.define "lab#{i}" do |node|
        node.vm.box = "centos-7.4-docker-17"
        node.ssh.insert_key = false
        node.vm.hostname = "lab#{i}"
        node.vm.network "private_network", ip: "11.11.11.11#{i}"
        node.vm.provision "shell",
          inline: "echo hello from node #{i}"
        node.vm.provider "virtualbox" do |v|
          v.cpus = 2
          v.customize ["modifyvm", :id, "--name", "lab#{i}", "--memory", "2048"]
        end
      end
    end
end
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在所有机器上安装kubeadm

参考之前的文章《centos7安装kubeadm》

配置所有节点的kubelet

# 配置kubelet使用国内可用镜像
# 修改/etc/systemd/system/kubelet.service.d/10-kubeadm.conf
# 添加如下配置 
Environment="KUBELET_EXTRA_ARGS=--pod-infra-container-image=registry.cn-shanghai.aliyuncs.com/gcr-k8s/pause-amd64:3.0"

# 使用命令
sed -i '/ExecStart=$/i Environment="KUBELET_EXTRA_ARGS=--pod-infra-container-image=registry.cn-shanghai.aliyuncs.com/gcr-k8s/pause-amd64:3.0"'  /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

# 重新载入配置
systemctl daemon-reload
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配置所有节点的hosts

cat >>/etc/hosts<复制代码

启动etcd集群

在lab1,lab2,lab3节点上启动etcd集群

# lab1
docker stop etcd && docker rm etcd
rm -rf /data/etcd
mkdir -p /data/etcd
docker run -d \
--restart always \
-v /etc/etcd/ssl/certs:/etc/ssl/certs \
-v /data/etcd:/var/lib/etcd \
-p 2380:2380 \
-p 2379:2379 \
--name etcd \
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd-amd64:3.1.12 \
etcd --name=etcd0 \
--advertise-client-urls=http://11.11.11.111:2379 \
--listen-client-urls=http://0.0.0.0:2379 \
--initial-advertise-peer-urls=http://11.11.11.111:2380 \
--listen-peer-urls=http://0.0.0.0:2380 \
--initial-cluster-token=9477af68bbee1b9ae037d6fd9e7efefd \
--initial-cluster=etcd0=http://11.11.11.111:2380,etcd1=http://11.11.11.112:2380,etcd2=http://11.11.11.113:2380 \
--initial-cluster-state=new \
--auto-tls \
--peer-auto-tls \
--data-dir=/var/lib/etcd

# lab2
docker stop etcd && docker rm etcd
rm -rf /data/etcd
mkdir -p /data/etcd
docker run -d \
--restart always \
-v /etc/etcd/ssl/certs:/etc/ssl/certs \
-v /data/etcd:/var/lib/etcd \
-p 2380:2380 \
-p 2379:2379 \
--name etcd \
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd-amd64:3.1.12 \
etcd --name=etcd1 \
--advertise-client-urls=http://11.11.11.112:2379 \
--listen-client-urls=http://0.0.0.0:2379 \
--initial-advertise-peer-urls=http://11.11.11.112:2380 \
--listen-peer-urls=http://0.0.0.0:2380 \
--initial-cluster-token=9477af68bbee1b9ae037d6fd9e7efefd \
--initial-cluster=etcd0=http://11.11.11.111:2380,etcd1=http://11.11.11.112:2380,etcd2=http://11.11.11.113:2380 \
--initial-cluster-state=new \
--auto-tls \
--peer-auto-tls \
--data-dir=/var/lib/etcd

# lab3
docker stop etcd && docker rm etcd
rm -rf /data/etcd
mkdir -p /data/etcd
docker run -d \
--restart always \
-v /etc/etcd/ssl/certs:/etc/ssl/certs \
-v /data/etcd:/var/lib/etcd \
-p 2380:2380 \
-p 2379:2379 \
--name etcd \
registry.cn-hangzhou.aliyuncs.com/google_containers/etcd-amd64:3.1.12 \
etcd --name=etcd2 \
--advertise-client-urls=http://11.11.11.113:2379 \
--listen-client-urls=http://0.0.0.0:2379 \
--initial-advertise-peer-urls=http://11.11.11.113:2380 \
--listen-peer-urls=http://0.0.0.0:2380 \
--initial-cluster-token=9477af68bbee1b9ae037d6fd9e7efefd \
--initial-cluster=etcd0=http://11.11.11.111:2380,etcd1=http://11.11.11.112:2380,etcd2=http://11.11.11.113:2380 \
--initial-cluster-state=new \
--auto-tls \
--peer-auto-tls \
--data-dir=/var/lib/etcd

# 验证查看集群
docker exec -ti etcd ash
etcdctl member list
etcdctl cluster-health
exit
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在第一台master节点初始化

# 生成token
# 保留token后面还要使用
token=$(kubeadm token generate)
echo $token

# 生成配置文件
cat >kubeadm-master.config<#imageRepository: registry.cn-shanghai.aliyuncs.com/gcr-k8s
imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers

api:
  advertiseAddress: 11.11.11.111

apiServerExtraArgs:
  endpoint-reconciler-type: lease

controllerManagerExtraArgs:
  node-monitor-grace-period: 10s
  pod-eviction-timeout: 10s

networking:
  podSubnet: 192.168.0.0/16

etcd:
  endpoints:
  - "http://11.11.11.111:2379"
  - "http://11.11.11.112:2379"
  - "http://11.11.11.113:2379"

apiServerCertSANs:
- "lab1"
- "lab2"
- "lab3"
- "11.11.11.111"
- "11.11.11.112"
- "11.11.11.113"
- "11.11.11.110"
- "127.0.0.1"

token: $token
tokenTTL: "0"

featureGates:
  CoreDNS: true
EOF

# 初始化
kubeadm init --config kubeadm-master.config
systemctl enable kubelet

# 保存初始化完成之后的join命令
# 如果丢失可以使用命令"kubeadm token list"获取
# kubeadm join 11.11.11.111:6443 --token nevmjk.iuh214fc8i0k3iue --discovery-token-ca-cert-hash sha256:0e4f738348be836ff810bce754e059054845f44f01619a37b817eba83282d80f

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


# 安装网络插件
# 下载配置
mkdir flannel && cd flannel
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

# 修改配置
# 此处的ip配置要与上面kubeadm的pod-network一致
  net-conf.json: |
    {
      "Network": "192.168.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }

# 修改镜像
image: registry.cn-shanghai.aliyuncs.com/gcr-k8s/flannel:v0.10.0-amd64

# 启动
kubectl apply -f kube-flannel.yml

# 如果Node有多个网卡的话，参考flannel issues 39701，
# https://github.com/kubernetes/kubernetes/issues/39701
# 目前需要在kube-flannel.yml中使用--iface参数指定集群主机内网网卡的名称，
# 否则可能会出现dns无法解析。容器无法通信的情况，需要将kube-flannel.yml下载到本地，
# flanneld启动参数加上--iface=
    containers:
      - name: kube-flannel
        image: registry.cn-shanghai.aliyuncs.com/gcr-k8s/flannel:v0.10.0-amd64
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=eth1

# 查看
kubectl get pods --namespace kube-system
kubectl get svc --namespace kube-system

# 设置master允许部署应用pod，参与工作负载，现在可以部署其他系统组件
# 如 dashboard, heapster, efk等
kubectl taint nodes --all node-role.kubernetes.io/master-
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启动其他master节点

# 打包第一台master初始化之后的/etc/kubernetes/pki目录
cd /etc/kubernetes && tar czvf /root/pki.tgz pki/ && cd ~

# 上传到其他master的/etc/kubernetes目录下
tar xf pki.tgz -C /etc/kubernetes/

# 删除pki目录下的apiserver.crt 和 apiserver.key文件
rm -rf /etc/kubernetes/pki/{apiserver.crt,apiserver.key}

# 生成配置文件
# 使用和之前master一样的配置文件
# token保持一致
cat >kubeadm-master.config<#imageRepository: registry.cn-shanghai.aliyuncs.com/gcr-k8s
imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers

# 注意修改IP
api:
  advertiseAddress: 11.11.11.112

apiServerExtraArgs:
  endpoint-reconciler-type: lease

controllerManagerExtraArgs:
  node-monitor-grace-period: 10s
  pod-eviction-timeout: 10s

networking:
  podSubnet: 192.168.0.0/16

etcd:
  endpoints:
  - "http://11.11.11.111:2379"
  - "http://11.11.11.112:2379"
  - "http://11.11.11.113:2379"

apiServerCertSANs:
- lab1
- lab2
- lab3
- "11.11.11.111"
- "11.11.11.112"
- "11.11.11.113"
- "11.11.11.110"
- "127.0.0.1"

token: nevmjk.iuh214fc8i0k3iue
tokenTTL: "0"

featureGates:
  CoreDNS: true
EOF

# 初始化
kubeadm init --config kubeadm-master.config
systemctl enable kubelet

# 查看状态
kubectl get pod --all-namespaces -o wide | grep lab1
kubectl get pod --all-namespaces -o wide | grep lab2
kubectl get pod --all-namespaces -o wide | grep lab3
kubectl get nodes -o wide
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配置haproxy代理和keepalived

在lab1,lab2,lab3节点上启动haproxy和keepalived

# 拉取haproxy镜像
docker pull haproxy:1.7.8-alpine
mkdir /etc/haproxy
cat >/etc/haproxy/haproxy.cfg<log 127.0.0.1 local0 err
  maxconn 50000
  uid 99
  gid 99
  #daemon
  nbproc 1
  pidfile haproxy.pid

defaults
  mode http
  log 127.0.0.1 local0 err
  maxconn 50000
  retries 3
  timeout connect 5s
  timeout client 30s
  timeout server 30s
  timeout check 2s

listen admin_stats
  mode http
  bind 0.0.0.0:1080
  log 127.0.0.1 local0 err
  stats refresh 30s
  stats uri     /haproxy-status
  stats realm   Haproxy\ Statistics
  stats auth    will:will
  stats hide-version
  stats admin if TRUE

frontend k8s-https
  bind 0.0.0.0:8443
  mode tcp
  #maxconn 50000
  default_backend k8s-https

backend k8s-https
  mode tcp
  balance roundrobin
  server lab1 11.11.11.111:6443 weight 1 maxconn 1000 check inter 2000 rise 2 fall 3
  server lab2 11.11.11.112:6443 weight 1 maxconn 1000 check inter 2000 rise 2 fall 3
  server lab3 11.11.11.113:6443 weight 1 maxconn 1000 check inter 2000 rise 2 fall 3
EOF

# 启动haproxy
docker run -d --name my-haproxy \
-v /etc/haproxy:/usr/local/etc/haproxy:ro \
-p 8443:8443 \
-p 1080:1080 \
--restart always \
haproxy:1.7.8-alpine

# 查看日志
docker logs my-haproxy

# 浏览器查看状态
http://11.11.11.111:1080/haproxy-status
http://11.11.11.112:1080/haproxy-status

# 拉取keepalived镜像
docker pull osixia/keepalived:1.4.4

# 启动
# 载入内核相关模块
lsmod | grep ip_vs
modprobe ip_vs

# 启动keepalived
# eth1为本次实验11.11.11.0/24网段的所在网卡
docker run --net=host --cap-add=NET_ADMIN \
-e KEEPALIVED_INTERFACE=eth1 \
-e KEEPALIVED_VIRTUAL_IPS="#PYTHON2BASH:['11.11.11.110']" \
-e KEEPALIVED_UNICAST_PEERS="#PYTHON2BASH:['11.11.11.111','11.11.11.112','11.11.11.113']" \
-e KEEPALIVED_PASSWORD=hello \
--name k8s-keepalived \
--restart always \
-d osixia/keepalived:1.4.4

# 查看日志
# 会看到两个成为backup 一个成为master
docker logs k8s-keepalived

# 此时会配置 11.11.11.110 到其中一台机器
# ping测试
ping -c4 11.11.11.110

# 如果失败后清理后，重新实验
docker rm -f k8s-keepalived
ip a del 11.11.11.110/32 dev eth1

# 修改~/.kube/config文件里ip和端口，然后使用kubectl测试
rm -rf .kube/cache .kube/http-cache
kubectl get pods -n kube-system -o wide
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修改master节点相关组件配置指向vip

# lab1 lab2 lab3
sed -i 's@server: https://11.11.11.*:6443@server: https://11.11.11.110:8443@g' /etc/kubernetes/{admin.conf,kubelet.conf,scheduler.conf,controller-manager.conf}

# 重启kubelet
systemctl daemon-reload
systemctl restart kubelet docker

# 查看所有节点状态
kubectl get nodes -o wide
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修改kube-proxy的配置

# 修改kube-proxy的配置指定vip
# 执行命令之后修改为 server: https://11.11.11.110:8443
kubectl edit -n kube-system configmap/kube-proxy

# 查看设置
kubectl get -n kube-system configmap/kube-proxy -o yaml

# 删除重建kube-proxy
kubectl get pods --all-namespaces -o wide | grep proxy
all_proxy_pods=$(kubectl get pods --all-namespaces -o wide | grep proxy | awk '{print $2}' | xargs)
echo $all_proxy_pods
kubectl delete pods $all_proxy_pods -n kube-system
kubectl get pods --all-namespaces -o wide | grep proxy
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启动node节点

# 加入master节点
# 这个命令是之前初始化master完成时，输出的命令
kubeadm join 11.11.11.110:8443 --token nevmjk.iuh214fc8i0k3iue --discovery-token-ca-cert-hash sha256:0e4f738348be836ff810bce754e059054845f44f01619a37b817eba83282d80f
systemctl enable kubelet
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修改node节点kubelet配置并重启

# 修改配置
sed -i 's@server: https://11.11.11.*:6443@server: https://11.11.11.110:8443@g' /etc/kubernetes/kubelet.conf

# 重启kubelet
systemctl daemon-reload
systemctl restart kubelet docker

# 查看所有节点状态
kubectl get nodes -o wide
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禁止master节点发布应用

设置master不接受负载

# 查看状态
kubectl get nodes

# 设置
# kubectl patch node lab1 -p '{"spec":{"unschedulable":true}}'
kubectl taint nodes lab1 lab2 lab3 node-role.kubernetes.io/master=true:NoSchedule

# 查看状态
kubectl get nodes
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测试

重建多个coredns副本

# 删除coredns的pods
kubectl get pods -n kube-system -o wide | grep coredns
all_coredns_pods=$(kubectl get pods -n kube-system -o wide | grep coredns | awk '{print $1}' | xargs)
echo $all_coredns_pods
kubectl delete pods $all_coredns_pods -n kube-system

# 修改副本数
# replicas: 3
# 可以修改为node节点的个数
kubectl edit deploy coredns -n kube-system

# 查看状态
kubectl get pods -n kube-system -o wide | grep coredns
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基础测试

1. 启动

# 直接使用命令测试
kubectl run nginx --replicas=2 --image=nginx:alpine --port=80
kubectl expose deployment nginx --type=NodePort --name=example-service-nodeport
kubectl expose deployment nginx --name=example-service

# 使用配置文件测试
cat >example-nginx.yml<type: NodePort
    ports:
      - name: http-nodeport
        port: 80
        nodePort: 32223
EOF
kubectl apply -f example-nginx.yml
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2. 查看状态

kubectl get deploy
kubectl get pods
kubectl get svc
kubectl describe svc example-service
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3. DNS解析

kubectl run curl --image=radial/busyboxplus:curl -i --tty
nslookup kubernetes
nslookup example-service
curl example-service

# 如果时间过长会返回错误，可以使用如下方式再进入测试
curlPod=$(kubectl get pod | grep curl | awk '{print $1}')
kubectl exec -ti $curlPod -- sh
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4. 访问测试

# 10.96.59.56 为查看svc时获取到的clusterip
curl "10.96.59.56:80"

# 32223 为查看svc时获取到的 nodeport
http://11.11.11.114:32223/
http://11.11.11.115:32223/
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3. 清理删除

kubectl delete svc example-service example-service-nodeport
kubectl delete deploy nginx curl
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高可用测试

关闭master节点测试集群是能否正常执行上一步的基础测试，查看相关信息，不能同时关闭lab1和lab2，因为上面有haproxy和keepalived服务

kubectl get pod --all-namespaces -o wide
kubectl get pod --all-namespaces -o wide | grep lab1
kubectl get pod --all-namespaces -o wide | grep lab2
kubectl get pod --all-namespaces -o wide | grep lab3
kubectl get nodes -o wide
kubectl get deploy
kubectl get pods
kubectl get svc
kubectl describe svc example-service
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注意事项

• 当直接把node节点关闭时，只有过了5分钟之后，上面的pod才会被检测到有问题，并迁移到其他节点

如果想快速迁移可以执行 kubectl delete node

也可以修改controller-manager的的pod-eviction-timeout参数，默认5m

node-monitor-grace-period参数，默认40s

参考文档

• https://kubernetes.io/docs/admin/high-availability/
• https://www.kubernetes.org.cn/3536.html
• https://github.com/indiketa/kubeadm-ha
• https://zhuanlan.zhihu.com/p/34740013
• https://github.com/cookeem/kubeadm-ha/blob/master/README_CN.md
• https://blog.frognew.com/2017/04/install-etcd-cluster.html
• https://blog.frognew.com/2017/04/install-ha-kubernetes-1.6-cluster.html
• https://medium.com/@bambash/ha-kubernetes-cluster-via-kubeadm-b2133360b198
• https://github.com/kubernetes/kubeadm/issues/546
• https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-init/#config-file