k8s高可用架構

地址sealos, 讓kubernetes高可用不再需要keepalived haproxy和ansible,sealyun定製超級版kubeadm透過ipvs代理多個master，優雅解決k8s高可用問題。

ip	role
10.103.97.200	master0
10.103.97.201	master0
10.103.97.202	master0
10.103.97.2	virtulIP

apiserver.cluster.local apiserver解析名

在每個節點上初始化

tar zxvf kube1.14.0.tar.gz && cd kube/shell && sh init.sh

用下載的kubeadm替換掉包內的kubeadm:

cp kubeadm /usr/bin/kubeadm

cat kubeadm-config.yaml :

apiVersion: kubeadm.k8s.io/v1beta1
kind: ClusterConfiguration
kubernetesVersion: v1.14.0
controlPlaneEndpoint: "apiserver.cluster.local:6443" # 使用解析名去訪問APIserver
apiServer:
        certSANs:
        - 127.0.0.1
        - apiserver.cluster.local
        - 172.20.241.205
        - 172.20.241.206
        - 172.20.241.207
        - 172.20.241.208
        - 10.103.97.2          # 虛擬IP等都加入到證書中
---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
mode: "ipvs"
ipvs:
        excludeCIDRs: 
        - "10.103.97.2/32" # 如果不加這個k8s會定時清理使用者建立的IPVS規則，導致代理失敗

在 master0 10.103.97.200 上

echo "10.103.97.200 apiserver.cluster.local" >> /etc/hosts
kubeadm init --config=kubeadm-config.yaml --experimental-upload-certs  
mkdir ~/.kube && cp /etc/kubernetes/admin.conf ~/.kube/config
kubectl apply -f 安裝calico

執行完會輸出一些日誌，裡面包含join需要用的

在 master1 10.103.97.201 上

# 注意，在安裝之前解析到master0, 安裝成功後解析改成自己,因為kubelet kube-proxy配置的都是這個解析名,如果不改解析master0當機整個叢集就不可用了
echo "10.103.97.200 apiserver.cluster.local" >> /etc/hosts 
kubeadm join 10.103.97.200:6443 --token 9vr73a.a8uxyaju799qwdjv \
    --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 \
    --experimental-control-plane \
    --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07 
sed "s/10.103.97.200/10.103.97.201/g" -i /etc/hosts  # 解析改也自己本機地址

在 master2 10.103.97.202 上，同master1

echo "10.103.97.200 apiserver.cluster.local" >> /etc/hosts
kubeadm join 10.103.97.200:6443 --token 9vr73a.a8uxyaju799qwdjv \
    --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 \
    --experimental-control-plane \
    --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07  
sed "s/10.103.97.200/10.103.97.201/g" -i /etc/hosts

透過虛擬IP join到master上, 這個 會在node節點上建立一條ipvs規則，virturl server就是虛擬IP， realserver就是三個master。 然後再以一個static pod起一個守護程式守護這些規則，一旦哪個apiserver不可訪問了就清除realserver, apiserver通了之後再次新增回來

echo "10.103.97.2 apiserver.cluster.local" >> /etc/hosts   # using vip
kubeadm join 10.103.97.2:6443 --token 9vr73a.a8uxyaju799qwdjv \
    --master 10.103.97.200:6443 \
    --master 10.103.97.201:6443 \
    --master 10.103.97.202:6443 \
    --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 
Architecture

  +----------+                       +---------------+  virturl server: 10.103.97.2:6443
  | mater0   |< ----------------------| ipvs nodes    |    real servers:
  +----------+                      |+---------------+            10.103.97.200:6443
                                    |                             10.103.97.201:6443
  +----------+                      |                             10.103.97.202:6443
  | mater1   |<---------------------+
  +----------+                      |
                                    |
  +----------+                      |
  | mater2   |<---------------------+
  +----------+

叢集每個node節點都會建立一條ipvs規則用於代理所有的master節點。類似kube-proxy的ipvs實現。

然後起一個守護程式就健康檢查

apiservers /etc/kubernetes/manifests/sealyun-lvscare.yaml