Kubernetes搭建流程（基于Centos7）

安装docker

• 安装docker环境必要的包

  sudo yum install -y yum-utils device-mapper-persistent-data lvm2
  

• 加入docker repo

  sudo yum-config-manager \
      --add-repo \
      https://download.docker.com/linux/centos/docker-ce.repo
  

• 安装docker-ce (ce 版本为社区版本，ee版本为商业版本)

  sudo yum makecache fast
  sudo yum install docker-ce
  

  安装过程中可能会出现依赖问题，缺少 container-selinux-2.9 这个安装包，此时需要执行以下安装命令

  sudo yum install ftp://fr2.rpmfind.net/linux/centos/7.3.1611/extras/x86_64/Packages/container-selinux-2.9-4.el7.noarch.rpm
  

  成功后继续执行

  sudo yum install docker-ce
  

• 启动docker服务

  sudo systemctl start docker.service
  

安装 kubectl

• 下载最新的kublet程序

  curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
  

• 添加可执行权限

  chmod +x ./kubectl
  

• 移动到系统环境中

  sudo mv ./kubectl /usr/local/bin/kubectl
  

安装 kubelet,kubectl

• 切换到root环境

  su root  或者  sudo -i
  

• 安装 kubelet 和 kubeadm

  cat <<EOF > /etc/yum.repos.d/kubernetes.repo
  [kubernetes]
  name=Kubernetes
  baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
  enabled=1
  gpgcheck=1
  repo_gpgcheck=1
  gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
            https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
  EOF
  setenforce 0
  yum install -y kubelet kubeadm
  

• 启动kubelet服务

  systemctl enable kubelet && systemctl start kubelet
  

初始化 mater node（该操作只需要在主节点上执行）

• 使用kubeadm初始化master

  kubeadm init
  

• 初始化输出示例

    [kubeadm] WARNING: kubeadm is in beta, please do not use it for production clusters.
    [init] Using Kubernetes version: v1.7.0
    [init] Using Authorization modes: [Node RBAC]
    [preflight] Running pre-flight checks
    [preflight] Starting the kubelet service
    [certificates] Generated CA certificate and key.
    [certificates] Generated API server certificate and key.
    [certificates] API Server serving cert is signed for DNS names [kubeadm-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.138.0.4]
    [certificates] Generated API server kubelet client certificate and key.
    [certificates] Generated service account token signing key and public key.
    [certificates] Generated front-proxy CA certificate and key.
    [certificates] Generated front-proxy client certificate and key.
    [certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
    [kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
    [kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
    [kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
    [kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
    [apiclient] Created API client, waiting for the control plane to become ready
    [apiclient] All control plane components are healthy after 16.502136 seconds
    [token] Using token: <token>
    [apiconfig] Created RBAC rules
    [addons] Applied essential addon: kube-proxy
    [addons] Applied essential addon: kube-dns
  
    Your Kubernetes master has initialized successfully!
  
    To start using your cluster, you need to run (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:
      http://kubernetes.io/docs/admin/addons/
  
    You can now join any number of machines by running the following on each node
    as root:
  
      kubeadm join --token <token> <master-ip>:<master-port>
  

• 执行上述输入中的内容（遗漏该步骤可能会导致 kube-dns pod 一直无法running的错误）

  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 pod network （用于pod以及docker容器之间进行网络通信）

  kubectl apply -f https://git.io/weave-kube-1.6
  

  Note:pod network 有多种，此处我们选择 weave，其他网络可自行研究

加入子节点

• 子节点加入到 Cluster

  kubeadm join --token <token> <master-ip>:<master-port>
  

安装dashboard

• 安装命令

  kubectl create -f https://git.io/kube-dashboard
  

• 运行dashboard（需要在主机上查看）

  执行 kubectl proxy
  

  浏览器访问： http://localhost:8081/ui

  k8s dashboard

问题汇总

• 执行 kubeadm init 后一直卡在

  [apiclient] Created API client, waiting for the control plane to become ready
  

  可使用以下命令查看日志

  journalctl -xeu kubelet
  

  问题原因： gcr.io/google_containers/pause-amd64:3.0 没有pull下来
  解决方式：docker pull gcr.io/google_containers/pause-amd64:3.0,若仍然pull不下来，可开启外网代理再使用docker pull

• kubelet: error: failed to run Kubelet: failed to create kubelet: misconfiguration: kubelet cgroup driver: "systemd" is different from docker cgroup driver: "cgroupfs"
  问题原因：kubelet 使用的cgroup driver和docker使用的不一致
  解决方式：修改kubelet配置文件： /etc/systemd/system/kubelet.service.d/10-kubeadm.conf，将systemd修改为 cgroupfs,重启kubelet ( systemctl restart kubelet )

• 使用kubectl get nodes 命令报错：The connection to the server localhost:8080 was refused - did you specify the right host or port?
  解决方式：添加 KUBECONFIG环境变量

  vim ~/.bash_profile
  末尾添加 export KUBECONFIG=/etc/kubernetes/admin.conf  
  source ~/.bash_profile
  

• 安装 kubelet kubeadm 报错：https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64/repodata/repomd.xml: [Errno 14] curl#7 - "Failed to connect to 2404:6800:4008:801::200e: 网络不可
  达"
  解决方式：开启外网代理安装

• kube-dns 一直无法处于 3/3 running 状态
  问题原因：使用 kubectl describe pod kube-dns --namespace=kube-system 查看发现如下log

  Readiness probe failed: Get http://10.32.0.3:8081/readiness: dial tcp 10.32.0.3:8081: getsockopt: connection refused
  

  解决方式：执行init后的 output：

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

  重启 docker kubelet

  systemctl restart docker.service
  systemctl restart kubelet.service