在kubeadm中，需手动安装Docker和kubeket服务，Docker运行容器引擎，kubelet是启动Pod的核心组件，每一个节点都安装好kubelet和Docker，那么运行容器和Pod的环境就准备好了，在此基础之上，使用Kubeadm工具自动配置kubelet并启动kubelet服务，将Master所有组件和Node上剩余的kube-proxy组件都运行为Pod，托管在k8s之上。
服务器规划
三台机器：一台master、两个Node：
- k8s-master：10.3.1.20
- k8s-node01：10.3.1.21
- k8s-node02：10.3.1.25
- OS：Ubuntu16.04
- Docker：docker-ce-17.03
安装前准备
1、master节点到各Node节点SSH免密登录。
2、时间同步。
3、各Node必须关闭swap：swapoff -a，否则kubelet启动失败。
4、各节点主机名和IP加入/etc/hosts解析
安装Doker
所有k8s节点安装Docker Daemon：
apt-get updateapt-get install ????apt-transport-https ????ca-certificates ????curl ????software-properties-commoncurl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -apt-key fingerprint 0EBFCD88add-apt-repository ????"deb [arch=amd64] https://download.docker.com/linux/ubuntu ????$(lsb_release -cs) ????stable"apt-get updateapt-get install -y docker-ce=17.03.2~ce-0~ubuntu-xenial安装完Docker后，设置FORWARD规则为ACCEPT
#默认为DROP iptables -P FORWARD ACCEPT安装kubeadm工具
- 所有节点都需要安装kubeadm
apt-get update && apt-get install -y apt-transport-https curlcurl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -echo ‘deb http://apt.kubernetes.io/ kubernetes-xenial main‘ >/etc/apt/sources.list.d/kubernetes.listapt-get updateapt-get install -y ?kubeadm#它会自动安装kubeadm、kubectl、kubelet、kubernetes-cni、socat安装完后，设置kubelet服务开机自启：
systemctl enable kubelet必须设置Kubelet开机自启动，才能让k8s集群各组件在系统重启后自动运行。
部署集群
有了上面这些基础设置后，就可以开始用kubeadm init部署k8s集群了。
在k8s-master上操作
这一步之前确保swap已关闭。
kubeadm ?init -h可查看帮助信息：
root@k8s-master:~# kubeadm ?init -h ##查看init可用的参数，这里使用这两个参数： ??--pod-network-cidr string ： 自定义Pod网络 ??--ignore-preflight-errors strings： 忽略一些错误开始初始化集群
root@k8s-master:~# kubeadm init ?--pod-network-cidr 172.29.0.0/16 --ignore-preflight-errors=all输出如下信息：
#初始化kubernetes，Kubeadm默认安装当前最新版本kubernetes[init] using Kubernetes version: v1.12.0#安装之前检测当前是否符合k8s运行环境，因为忽略了所有错误所以这里很快就通过了。[preflight] running pre-flight checks[preflight/images] Pulling images required for setting up a Kubernetes cluster[preflight/images] This might take a minute or two, depending on the speed of your internet connection[preflight/images] You can also perform this action in beforehand using ‘kubeadm config images pull‘#写入kubelet相关配置文件，并启动kubelet服务[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"[preflight] Activating the kubelet service#自动生成集群用到的证书[certificates] Generated front-proxy-ca certificate and key.[certificates] Generated front-proxy-client certificate and key.[certificates] Generated etcd/ca certificate and key.[certificates] Generated etcd/server certificate and key.[certificates] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [127.0.0.1 ::1][certificates] Generated apiserver-etcd-client certificate and key.[certificates] Generated etcd/peer certificate and key.[certificates] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [10.3.1.20 127.0.0.1 ::1][certificates] Generated etcd/healthcheck-client certificate and key.[certificates] Generated ca certificate and key.[certificates] Generated apiserver-kubelet-client certificate and key.[certificates] Generated apiserver certificate and key.[certificates] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.3.1.20][certificates] valid certificates and keys now exist in "/etc/kubernetes/pki"[certificates] Generated sa key and public key.#生成kubelet配置信息写入相应的文件[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"#生成pod清单文件，kubelet将根据此清单文件创建各组件的Pod[controlplane] wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"[controlplane] wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"[controlplane] wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"#根据清单目录开始启动Pod[init] waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests" [init] this might take a minute or longer if the control plane images have to be pulled[apiclient] All control plane components are healthy after 20.003530 seconds[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace[kubelet] Creating a ConfigMap "kubelet-config-1.12" in namespace kube-system with the configuration for the kubelets in the cluster#给Master设置一个labele且设置一个taint[markmaster] Marking the node k8s-master as master by adding the label "node-role.kubernetes.io/master=‘‘"[markmaster] Marking the node k8s-master as master by adding the taints [node-role.kubernetes.io/master:NoSchedule]#集群的一些基础设置[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "k8s-master" as an annotation[bootstraptoken] using token: mwfr7m.57rmd56ghjyu0716[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public" namespace[addons] Applied essential addon: CoreDNS[addons] Applied essential addon: kube-proxy#提示master已初始化成功Your Kubernetes master has initialized successfully!To start using your cluster, you need to run the following as a regular user:#需要执行下面三条命令 ?mkdir -p $HOME/.kube ?sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config ?sudo chown $(id -u):$(id -g) $HOME/.kube/configYou should now deploy a pod network to the cluster.Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at: ?https://kubernetes.io/docs/concepts/cluster-administration/addons/You can now join any number of machines by running the following on each nodeas root: ?kubeadm join 10.3.1.20:6443 --token mwfr7m.57rmd56ghjyu0716 --discovery-token-ca-cert-hash sha256:8fbd33519b0203e9aa03cc882cb5489b5e6ad455f97581b1abf8ceb1dca8f622#把上面kubeadm join这一句话把这个记录下来，否则以后找起来有点麻烦，在node端加入时用到。- 根据提示执行：
root@k8s-master:~# mkdir -p $HOME/.kuberoot@k8s-master:~# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/configroot@k8s-master:~# sudo chown $(id -u):$(id -g) $HOME/.kube/config在Node上操作
在所有Node上使用kubeadm join加入集群：
#确保swap已关闭#复制在master节点上记录下的那句话，以加入集群root@k8s-node01:~# kubeadm join 10.3.1.20:6443 --token mwfr7m.57rmd56ghjyu0716 --discovery-token-ca-cert-hash sha256:8fbd33519b0203e9aa03cc882cb5489b5e6ad455f97581b1abf8ceb1dca8f622输出如下信息：
[preflight] running pre-flight checks ???[WARNING RequiredIPVSKernelModulesAvailable]: the IPVS proxier will not be used, because the following required kernel modules are not loaded: [ip_vs_rr ip_vs_wrr ip_vs_sh ip_vs] or no builtin kernel ipvs support: map[ip_vs:{} ip_vs_rr:{} ip_vs_wrr:{} ip_vs_sh:{} nf_conntrack_ipv4:{}]you can solve this problem with following methods: 1. Run ‘modprobe -- ‘ to load missing kernel modules;2. Provide the missing builtin kernel ipvs support[discovery] Trying to connect to API Server "10.3.1.20:6443"[discovery] Created cluster-info discovery client, requesting info from "https://10.3.1.20:6443"[discovery] Requesting info from "https://10.3.1.20:6443" again to validate TLS against the pinned public key[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "10.3.1.20:6443"[discovery] Successfully established connection with API Server "10.3.1.20:6443"[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"[preflight] Activating the kubelet service[tlsbootstrap] Waiting for the kubelet to perform the TLS Bootstrap...[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "k8s-node01" as an annotationThis node has joined the cluster:* Certificate signing request was sent to apiserver and a response was received.* The Kubelet was informed of the new secure connection details.Run ‘kubectl get nodes‘ on the master to see this node join the cluster.init完后，节点已加入群集。
最后，在master节点查看：
root@k8s-master:~# kubectl get nodeNAME ?????????STATUS ????ROLES ???AGE ????VERSIONk8s-master ???NotReady ??master ??6m39s ??v1.12.0k8s-node01 ??NotReady ??<none> ??4m31s ??v1.12.0k8s-node02 ??NotReady ??<none> ??97s ????v1.12.0去除master的taint，使用master也能被调度pod
root@k8s-master:~# kubectl taint nodes k8s-master node-role.kubernetes.io/master-node/k8s-master untainted安装CNI插件
各Node节点处于"NotReady" ，需要安装一个CNI网络插件：
root@k8s-master:~# ?kubectl apply -f https://docs.projectcalico.org/v3.1/getting-started/kubernetes/installation/hosted/kubeadm/1.7/calico.yamlconfigmap/calico-config configureddaemonset.extensions/calico-etcd createdservice/calico-etcd createddaemonset.extensions/calico-node createddeployment.extensions/calico-kube-controllers createdclusterrolebinding.rbac.authorization.k8s.io/calico-cni-plugin createdclusterrole.rbac.authorization.k8s.io/calico-cni-plugin createdserviceaccount/calico-cni-plugin createdclusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers createdclusterrole.rbac.authorization.k8s.io/calico-kube-controllers createdserviceaccount/calico-kube-controllers unchangedroot@k8s-master:~# 几分钟后，各Node全部Ready：
#各节点已正常运行root@k8s-master:~# kubectl get nodeNAME ????????STATUS ??ROLES ???AGE ??VERSIONk8s-master ??Ready ???master ??1h ??v1.12.0k8s-node01 ??Ready ???<none> ??1h ??v1.12.0k8s-node02 ??Ready ???<none> ??1h ??v1.12.0至此，所有组件全部运行：
root@k8s-master:~# kubectl get pod -n kube-systemNAME ??????????????????????????????????????READY ??STATUS ???RESTARTS ??AGEcalico-etcd-d7v6w ?????????????????????????1/1 ????Running ??0 ?????????3m21scalico-kube-controllers-75fb4f8996-dg7hd ??1/1 ????Running ??0 ?????????3m20scalico-node-794nd ?????????????????????????2/2 ????Running ??0 ?????????3m19scalico-node-b852z ?????????????????????????2/2 ????Running ??0 ?????????3m19scalico-node-z7f4n ?????????????????????????2/2 ????Running ??0 ?????????3m19scoredns-576cbf47c7-7svmm ??????????????????1/1 ????Running ??0 ?????????15hcoredns-576cbf47c7-kzbv2 ??????????????????1/1 ????Running ??0 ?????????15hetcd-k8s-master ???????????????????????????1/1 ????Running ??0 ?????????15hkube-apiserver-k8s-master ?????????????????1/1 ????Running ??0 ?????????15hkube-controller-manager-k8s-master ????????1/1 ????Running ??0 ?????????15hkube-proxy-7n5z9 ??????????????????????????1/1 ????Running ??0 ?????????15hkube-proxy-rwq9g ??????????????????????????1/1 ????Running ??0 ?????????15hkube-proxy-v7qnx ??????????????????????????1/1 ????Running ??0 ?????????15hkube-scheduler-k8s-master ?????????????????1/1 ????Running ??0 ?????????15hroot@k8s-master:~# 测试集群
配置kubectl的命令补全功能
命令补全功能由安装包"bash-completion"提供，Ubuntu系统中默认已安装。当前shell生效：source <(kubectl completion bash)永久生效：echo "source <(kubectl completion bash)" >> ~/.bashrc- 启动一个pod验证集群是否正常运行。
#run一个deploymentkubectl run -hUsage: ?kubectl run NAME --image=image [--env="key=value"] [--port=port] [--replicas=replicas] [--dry-run=bool][--overrides=inline-json] [--command] -- [COMMAND] [args...] [options]启动一个nginx
kubectl run nginx --image=nginx:1.10 --port=80deployment.apps/nginx created#查看root@k8s-master:~# kubectl get pod -w -o wideNAME ????????????????????READY ??STATUS ?????????????RESTARTS ??AGE ??IP ??????NODE ????????NOMINATED NODEnginx-787b58fd95-p9jwl ??0/1 ????ContainerCreating ??0 ?????????59s ??<none> ??k8s-node02 ??<none>nginx-787b58fd95-p9jwl ??1/1 ??Running ??0 ????70s ??192.168.58.193 ??k8s-node02 ??<none>- 测试nginx正常访问
root@k8s-master:~# curl ?-I 192.168.58.193HTTP/1.1 200 OKServer: nginx/1.10.3Date: Sat, 29 Sep 2018 02:42:06 GMTContent-Type: text/htmlContent-Length: 612Last-Modified: Tue, 31 Jan 2017 15:01:11 GMTConnection: keep-aliveETag: "5890a6b7-264"Accept-Ranges: bytes - 把nginx暴露一个端口出来，以使集群之外能访问
kubectl expose -h Usage:kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP|SCTP] [--target-port=number-or-name][--name=name] [--external-ip=external-ip-of-service] [--type=type] [options]root@k8s-master:~# kubectl expose deployment nginx --port=801 --target-port=80 --type=NodePort --name nginx-svcservice/nginx-svc exposedroot@k8s-master:~# - 查看服务：
root@k8s-master:~# kubectl get svcNAME ????????TYPE ???????CLUSTER-IP ?????EXTERNAL-IP ??PORT(S) ????????AGEkubernetes ??ClusterIP ??10.96.0.1 ??????<none> ???????443/TCP ????????16hnginx-svc ???NodePort ???10.100.84.207 ??<none> ???????801:30864/TCP ??25s
现在可以访问任意Node的30864端口访问到nginx服务：
root@k8s-node01:~# curl 10.3.1.21:30864<!DOCTYPE html><html><head><title>Welcome to nginx!</title><style> ???body { ???????width: 35em; ???????margin: 0 auto; ???????font-family: Tahoma, Verdana, Arial, sans-serif; ???}</style></head><body>如果发现哪个某个Node端口无法访问，则设置默认FORWARD规则为ACCEPT
iptables -P FORWARD ACCEPTkubeadm集群配置到此完成，可参考官方文档
kubernetes之Kubeadm快速安装版
原文地址：http://blog.51cto.com/newfly/2288003