三、k8s集群可用性验证与调参（第一章、k8s高可用集群安装）

作者：北京小远

出处：http://www.cnblogs.com/bj-xy/

参考课程:Kubernetes全栈架构师(电脑端购买优惠)

文档禁止转载，转载需标明出处,否则保留追究法律责任的权利!

目录：

目录

• 一、集群可用性验证
  • 1、1查看基本组件情况
  • 1、2创建测试pod
  • 1.3 测试连通性
• 二、参数优化
  • 2.1 容器配置参数优化
  • 2.2 controller-manager配置参数优化
  • 2.3 kubelet配置参数优化
  • 2.4 更改master节点的ROLES
• 三、设置coredns为自动扩容(可以不做)

一、集群可用性验证

k8s安装完成后需要进行可用性验证，因为k8s中有pod通信 server通信 node通信要保证通信正常

1、1查看基本组件情况

kubectl get node
kubectl get po -n kube-system

1、2创建测试pod

cat<<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: busybox
  namespace: default
spec:
  containers:
  - name: busybox
    image: busybox:1.28
    command:
      - sleep
      - "3600"
    imagePullPolicy: IfNotPresent
  restartPolicy: Always
EOF

1.3 测试连通性

1、测试pod能否解析同namespace的kubernetes的 svc
kubectl  get svc （查看kubernetes的svc）
kubectl exec busybox -n default -- nslookup kubernetes (解析)

结果:
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local

2、测试pod能否解析跨namespace的 svc
kubectl  get svc -n kube-system
kubectl exec busybox -n default -- nslookup kube-dns.kube-system
结果:
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kube-dns.kube-system
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

3、测试每个节点能否访问kubernetes svc的443端口 与kube-dns service的53端口
kubectl  get svc  获取 cluster ip
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   24d
在每个节点执行
telnet 10.96.0.1 443

测试kube-dns的联通
kubectl  get svc -n kube-system
NAME             TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                  AGE
kube-dns         ClusterIP   10.96.0.10      <none>        53/UDP,53/TCP,9153/TCP   21d
metrics-server   ClusterIP   10.111.181.43   <none>        443/TCP                  21d

在每个节点执行
telnet 10.96.0.10  53

4、测试pod之间能否通信
kubectl  get po -n kube-system -owide 获取pod

进入到calico-node的某台容器中
kubectl exec -it calico-node-2zkq8 -n kube-system -- bash
然后找一个其他节点的 calico-node pod的一个ip ping测试连通性

测试与busybox 测试容器的连通性
kubectl get po -owide

5、清除测试pod
kubectl delete po busybox
查看是否删除
kubectl  get po

二、参数优化

2.1 容器配置参数优化

每台机器执行
cat > /etc/docker/daemon.json <<EOF
{
        "exec-opts": ["native.cgroupdriver=systemd"],
        "log-driver": "json-file",
        "log-opts": {
                "max-size": "50m",
                "max-file": "3"
        },
        "registry-mirrors": ["https://ufkb7xyg.mirror.aliyuncs.com"],
        "max-concurrent-downloads": 10,
        "max-concurrent-uploads": 5,
        "live-restore": true
}
EOF

systemctl daemon-reload
systemctl restart docker
#删除状态是exited的容器
docker rm $(docker ps -q -f status=exited)

参数解析:
exec-opts：docker的CgroupDriver改成systemd
log-driver：日志格式
log-opts：日志存储大小与份数
registry-mirrors：镜像下载代理地址
max-concurrent-downloads：镜像下载启动的进程
max-concurrent-uploads：镜像上传启动的进程
live-restore：配置守护进程，让重启docker服务不重启容器

2.2 controller-manager配置参数优化

master节点配置
vim /usr/lib/systemd/system/kube-controller-manager.service
--cluster-signing-duration=43800h0m0s \

systemctl daemon-reload
systemctl restart kube-controller-manager

设置自动办法证书周期：
最大支持5年
--cluster-signing-duration

2.3 kubelet配置参数优化

每台机器执行
vim  /etc/systemd/system/kubelet.service.d/10-kubelet.conf
Environment="KUBELET_EXTRA_ARGS=--node-labels=node.kubernetes.io/node='' --tls-cipher-suites=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384    --image-pull-progress-deadline=30m " 

解析
-tls-cipher-suites= 加密方式因为默认的加密方式不安全
--image-pull-progress-deadline 设置下载镜像的 deadline避免重复尝试

vim /opt/kubernetes/kubelet-conf.yml
rotateServerCertificates: true
allowedUnsafeSysctls:
 - "net.core*"
 - "net.ipv4.*"
kubeReserved:
  cpu: "100m"
  memory: 300Mi
  ephemeral-storage: 10Gi
systemReserved:
  cpu: "100m"
  memory: 300Mi
  ephemeral-storage: 10Gi

解析：
rotateServerCertificates 自动配置证书
allowedUnsafeSysctls 允许就该内核参数
kubeReserved    预留系统资源给k8s 根据机器资源分配
systemReserved

systemctl daemon-reload
systemctl restart kubelet

2.4 更改master节点的ROLES

设置所有master节点的角色
kubectl label node k8s1 node-role.kubernetes.io/master=""

三、设置coredns为自动扩容(可以不做)

官方文档

git项目地址

官方资源配置文件

1、资源配置文件
cat > dns-horizontal-autoscaler_v1.9.yaml << EOF
kind: ServiceAccount
apiVersion: v1
metadata:
  name: kube-dns-autoscaler
  namespace: kube-system
  labels:
    addonmanager.kubernetes.io/mode: Reconcile
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: system:kube-dns-autoscaler
  labels:
    addonmanager.kubernetes.io/mode: Reconcile
rules:
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["list", "watch"]
  - apiGroups: [""]
    resources: ["replicationcontrollers/scale"]
    verbs: ["get", "update"]
  - apiGroups: ["apps"]
    resources: ["deployments/scale", "replicasets/scale"]
    verbs: ["get", "update"]
# Remove the configmaps rule once below issue is fixed:
# kubernetes-incubator/cluster-proportional-autoscaler#16
  - apiGroups: [""]
    resources: ["configmaps"]
    verbs: ["get", "create"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: system:kube-dns-autoscaler
  labels:
    addonmanager.kubernetes.io/mode: Reconcile
subjects:
  - kind: ServiceAccount
    name: kube-dns-autoscaler
    namespace: kube-system
roleRef:
  kind: ClusterRole
  name: system:kube-dns-autoscaler
  apiGroup: rbac.authorization.k8s.io

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: kube-dns-autoscaler
  namespace: kube-system
  labels:
    k8s-app: kube-dns-autoscaler
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
spec:
  selector:
    matchLabels:
      k8s-app: kube-dns-autoscaler
  template:
    metadata:
      labels:
        k8s-app: kube-dns-autoscaler
      annotations:
        seccomp.security.alpha.kubernetes.io/pod: 'docker/default'
    spec:
      priorityClassName: system-cluster-critical
      securityContext:
        supplementalGroups: [ 65534 ]
        fsGroup: 65534
      nodeSelector:
        kubernetes.io/os: linux
      containers:
      - name: autoscaler
        image: registry.cn-beijing.aliyuncs.com/yuan-k8s/cluster-proportional-autoscaler-amd64:1.8.1
        resources:
            requests:
                cpu: "20m"
                memory: "10Mi"
        command:
          - /cluster-proportional-autoscaler
          - --namespace=kube-system
          - --configmap=kube-dns-autoscaler
          - --target=deployment/coredns
          - --default-params={"linear":{"coresPerReplica":16,"nodesPerReplica":4,"min":2,"max":4,"preventSinglePointFailure":true,"includeUnschedulableNodes":true}}
          - --logtostderr=true
          - --v=2
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"
      serviceAccountName: kube-dns-autoscaler
EOF

2、解析
-default-params中的参数
min:coredns最小数
max:coredns最打数
coresPerReplica:集群CPU核心数
nodesPerReplica:集群节点数
preventSinglePointFailure:设置为 时true，如果有多个节点，控制器确保至少有 2 个副本
includeUnschedulableNodes被设定为true，副本将刻度基于节点的总数。否则副本将仅根据可调度节点的数量进行扩展

注意:
- --target= 这里与kube-dns.yaml中定义的name一致

如果报错没有ConfigMap则创建下面的资源
cat > dns-autoscaler-ConfigMap.yaml << EOF
kind: ConfigMap
apiVersion: v1
metadata:
  name: dns-autoscaler
  namespace: kube-system
data:
  linear: |-
    {
      "coresPerReplica": 16,
      "nodesPerReplica": 4,
      "min": 2,
      "preventSinglePointFailure": true
    }
EOF

3、创建
dns-horizontal-autoscaler_v1.9.yaml 

4、查看
kubectl  get po -n kube-system