近在准备研究生论文开题，提前搭一下要用到的Kubernetes集群练练手感。半个月前，Kubernetes 1.5正式发布，最大的亮点是支持了在Windows下运行容器，同时也简化了使用kubeadm安装集群的步骤。为了紧跟最时尚的潮流，我想试试用kubeadm搭一个1.5版本的集群出来。不过由于最近又过圣诞又要跨年，所以拖拖拉拉搭了一个星期多才搭好。也碰到了很多坑，尤其是翻墙问题真的神烦 (:зゝ∠) 所以在这里把Ubuntu 16.04上搭集群的过程写下来，造福社会！
一、环境准备我准备了三台Ubuntu 16.04虚拟机，各项参数如下：
节点IP地址CPU内存master 192.168.0.158 4核 4GB
node1 192.168.0.159 1核 2GB
node2 192.168.0.160 1核 2GB
Kubernetes官网上提到每台机器至少要有1GB内存，不然集群起来之后，留给运行在容器内的应用的内存就很少了。同时要保证所有机器之前的网络是互相连通的。
这里再说一下，一开始我只给master分配了2个核，但是等我把kubeadm跑起来后，docker在pull一些必需的镜像时会出现OutOfCPU的情况，大概是因为kubeadm把第一台机器做master以及第一个node，所以初始化的服务都跑在这台机器上？所以后来我把master加到了4核。
二、搭建步骤 （1/4）安装docker、kubelet、kubeadm和kubectl以root用户ssh到每台机器上，运行：
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add - cat <<EOF > /etc/apt/sources.list.d/kubernetes.list deb kubernetes-xenial main EOF apt-get update # 先安装docker apt-get install -y docker.io apt-get install -y kubelet kubeadm kubectl kubernetes-cni （2/4）初始化master装好kubelet和kubectl后，在master上以root用户运行：
kubeadm init --token=yiqian.123456注意： 官方文档上kubeadm init的时候是不带token的，但我这样运行之后，console也没给我一个默认的token(exo me???)。但其他节点在加入集群的时候是需要指定master的token的，所以我在kubeadm初始化的时候手动给master指定了一个token。
这里还有一个坑就是，如果初始化失败了，比如像Issue#33544，那么你停掉再重新init会出错，这是因为kubeadm在安装了相关包之后会生成/etc/kubernetes、/var/lib/kubelet等目录，所以我们先需要手动清理一下再重新初始化：
systemctl stop kubelet; docker rm -f $(docker ps -q); mount | grep "/var/lib/kubelet/*" | awk '{print $3}' | xargs umount 1>/dev/null 2>/dev/null; rm -rf /var/lib/kubelet /etc/kubernetes /var/lib/etcd /etc/cni; systemctl start kubelet; kubeadm init --token=<token>最后，init成功的运行输出如下：
root@xyq-k8s-master:/home/administrator# kubeadm init --token=yiqian.123456 [kubeadm] WARNING: kubeadm is in alpha, please do not use it for production clusters. [preflight] Running pre-flight checks [init] Using Kubernetes version: v1.5.1 [tokens] Validating provided token [tokens] Accepted provided token [certificates] Generated Certificate Authority key and certificate. [certificates] Generated API Server key and certificate [certificates] Generated Service Account signing keys [certificates] Created keys and certificates in "/etc/kubernetes/pki" [kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf" [kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf" [apiclient] Created API client, waiting for the control plane to become ready [apiclient] All control plane components are healthy after 14.534854 seconds [apiclient] Waiting for at least one node to register and become ready [apiclient] First node is ready after 0.506558 seconds [apiclient] Creating a test deployment [apiclient] Test deployment succeeded [token-discovery] Created the kube-discovery deployment, waiting for it to become ready [token-discovery] kube-discovery is ready after 2.005108 seconds [addons] Created essential addon: kube-proxy [addons] Created essential addon: kube-dns Your Kubernetes master has initialized successfully! You should now deploy a pod network to the cluster. Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at: You can now join any number of machines by running the following on each node: kubeadm join --token=yiqian.123456 192.168.0.158