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Kubeadm搭建单master节点的Kubernetes集群

1. 环境准备

3个节点,都是 Centos 7.6 系统,内核版本:3.10.0-957.12.2.el7.x86_64,在每个节点上添加 hosts 信息:

$ cat /etc/hosts    172.16.1.128 k8s-master  172.16.1.129 k8s-node01  172.16.1.130 k8s-node02

禁用防火墙:

$ systemctl stop firewalld  $ systemctl disable firewalld

禁用SELINUX:

$ setenforce 0  $ cat /etc/selinux/config  SELINUX=disabled

创建/etc/sysctl.d/k8s.conf文件,添加如下内容:

net.bridge.bridge-nf-call-ip6tables = 1  net.bridge.bridge-nf-call-iptables = 1  net.ipv4.ip_forward = 1

执行如下命令使修改生效:

$ modprobe br_netfilter  $ sysctl -p /etc/sysctl.d/k8s.conf

安装 ipvs

$ cat > /etc/sysconfig/modules/ipvs.modules <<EOF  #!/bin/bash  modprobe -- ip_vs  modprobe -- ip_vs_rr  modprobe -- ip_vs_wrr  modprobe -- ip_vs_sh  modprobe -- nf_conntrack_ipv4  EOF  $ chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

上面脚本创建了的/etc/sysconfig/modules/ipvs.modules文件,保证在节点重启后能自动加载所需模块。使用lsmod | grep -e ip_vs -e nf_conntrack_ipv4命令查看是否已经正确加载所需的内核模块。

接下来还需要确保各个节点上已经安装了 ipset 软件包:

$ yum install ipset -y

为了便于查看 ipvs 的代理规则,最好安装一下管理工具 ipvsadm:

$ yum install ipvsadm -y

同步服务器时间

$ yum install chrony -y  $ systemctl enable chronyd  $ systemctl start chronyd  $ chronyc sources

关闭 swap 分区:

$ swapoff -a

修改/etc/fstab文件,注释掉 SWAP 的自动挂载,使用free -m确认 swap 已经关闭。swappiness 参数调整,修改/etc/sysctl.d/k8s.conf添加下面一行:

vm.swappiness=0

执行sysctl -p /etc/sysctl.d/k8s.conf使修改生效。

接下来可以安装 Docker

$ yum install -y yum-utils    device-mapper-persistent-data    lvm2  $ yum-config-manager    --add-repo    https://download.docker.com/linux/centos/docker-ce.repo  $ yum list docker-ce --showduplicates | sort -r

可以选择安装一个版本,比如我们这里安装最新版本:

$ yum install docker-ce-18.09.8-3.el7 -y

配置 Docker 镜像加速器

$ vi /etc/docker/daemon.json    {   "exec-opts": ["native.cgroupdriver=systemd"],   "registry-mirrors" : [   "https://ot2k4d59.mirror.aliyuncs.com/"   ]  }

启动 Docker

$ systemctl start docker  $ systemctl enable docker

在确保 Docker 安装完成后,上面的相关环境配置也完成了,现在我们就可以来安装 Kubeadm 了,我们这里是通过指定yum 源的方式来进行安装的:

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

当然了,上面的 yum 源是需要科学上网的,如果不能科学上网的话,我们可以使用阿里云的源进行安装:

cat <<EOF > /etc/yum.repos.d/kubernetes.repo  [kubernetes]  name=Kubernetes  baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64  enabled=1  gpgcheck=0  repo_gpgcheck=0  gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg   http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg  EOF

然后安装 kubeadm、kubelet、kubectl(我安装的是最新版,有版本要求自己设定版本):

$ yum install -y kubelet-1.17.2 kubeadm-1.17.2 kubectl-1.17.2 --disableexcludes=kubernetes

可以看到我们这里安装的是 v1.17.2 版本,然后将 kubelet 设置成开机启动:

$ systemctl enable kubelet.service

到这里为止上面所有的操作都需要在所有节点执行配置。

2. 初始化集群

然后接下来在 master 节点配置 kubeadm 初始化文件,可以通过如下命令导出默认的初始化配置:

$ kubeadm config print init-defaults > kubeadm.yaml

然后根据我们自己的需求修改配置,比如修改 imageRepository 的值,kube-proxy 的模式为 ipvs,另外需要注意的是我们这里是准备安装 calico 网络插件的,需要将 networking.podSubnet 设置为192.168.0.0/16:

apiVersion: kubeadm.k8s.io/v1beta2  bootstrapTokens:  - groups:    - system:bootstrappers:kubeadm:default-node-token    token: abcdef.0123456789abcdef    ttl: 24h0m0s    usages:    - signing    - authentication  kind: InitConfiguration  localAPIEndpoint:    advertiseAddress: 172.16.1.128    bindPort: 6443  nodeRegistration:    criSocket: /var/run/dockershim.sock    name: k8s-master    taints:    - effect: NoSchedule      key: node-role.kubernetes.io/master  ---  apiServer:    timeoutForControlPlane: 4m0s  apiVersion: kubeadm.k8s.io/v1beta2  certificatesDir: /etc/kubernetes/pki  clusterName: kubernetes  controllerManager: {}  dns:    type: CoreDNS  etcd:    local:      dataDir: /var/lib/etcd  imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers  kind: ClusterConfiguration  kubernetesVersion: v1.17.2  networking:    dnsDomain: cluster.local    podSubnet: 192.168.0.0/16    serviceSubnet: 10.96.0.0/12  scheduler: {}  ---  apiVersion: kubeproxy.config.k8s.io/v1alpha1  kind: KubeProxyConfiguration  mode: ipvs

然后使用上面的配置文件进行初始化:

$ kubeadm init --config kubeadm.yaml    [init] Using Kubernetes version: v1.17.2  [preflight] Running pre-flight checks   [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 19.03.1. Latest validated version: 18.09  [preflight] Pulling images required for setting up a Kubernetes cluster  [preflight] This might take a minute or two, depending on the speed of your internet connection  [preflight] You can also perform this action in beforehand using 'kubeadm config images pull'  [kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"  [kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"  [kubelet-start] Activating the kubelet service  [certs] Using certificateDir folder "/etc/kubernetes/pki"  [certs] Generating "etcd/ca" certificate and key  [certs] Generating "etcd/server" certificate and key  [certs] etcd/server serving cert is signed for DNS names [ydzs-master localhost] and IPs [10.151.30.11 127.0.0.1 ::1]  [certs] Generating "etcd/peer" certificate and key  [certs] etcd/peer serving cert is signed for DNS names [ydzs-master localhost] and IPs [10.151.30.11 127.0.0.1 ::1]  [certs] Generating "apiserver-etcd-client" certificate and key  [certs] Generating "etcd/healthcheck-client" certificate and key  [certs] Generating "ca" certificate and key  [certs] Generating "apiserver" certificate and key  [certs] apiserver serving cert is signed for DNS names [ydzs-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.151.30.11]  [certs] Generating "apiserver-kubelet-client" certificate and key  [certs] Generating "front-proxy-ca" certificate and key  [certs] Generating "front-proxy-client" certificate and key  [certs] Generating "sa" key and public key  [kubeconfig] Using kubeconfig folder "/etc/kubernetes"  [kubeconfig] Writing "admin.conf" kubeconfig file  [kubeconfig] Writing "kubelet.conf" kubeconfig file  [kubeconfig] Writing "controller-manager.conf" kubeconfig file  [kubeconfig] Writing "scheduler.conf" kubeconfig file  [control-plane] Using manifest folder "/etc/kubernetes/manifests"  [control-plane] Creating static Pod manifest for "kube-apiserver"  [control-plane] Creating static Pod manifest for "kube-controller-manager"  [control-plane] Creating static Pod manifest for "kube-scheduler"  [etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"  [wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s  [kubelet-check] Initial timeout of 40s passed.  [apiclient] All control plane components are healthy after 42.012149 seconds  [upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace  [kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster  [upload-certs] Skipping phase. Please see --upload-certs  [mark-control-plane] Marking the node ydzs-master as control-plane by adding the label "node-role.kubernetes.io/master=''"  [mark-control-plane] Marking the node ydzs-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]  [bootstrap-token] Using token: abcdef.0123456789abcdef  [bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles  [bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials  [bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token  [bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster  [bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace  [addons] Applied essential addon: CoreDNS  [addons] Applied essential addon: kube-proxy  Your Kubernetes control-plane has initialized successfully!  To start using your cluster, you need to run the following 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:   https://kubernetes.io/docs/concepts/cluster-administration/addons/  Then you can join any number of worker nodes by running the following on each as root:  kubeadm join 172.16.1.128:6443 --token abcdef.0123456789abcdef    --discovery-token-ca-cert-hash sha256:deb5158b39948a4592ff48512047ea6e45b288c248872724a28f15008962178b

可以看到最新验证的 docker 版本是18.09,虽然是一个 warning,所以最好还是安装18.09版本的 docker。

拷贝 kubeconfig 文件

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

记住初始化集群上面的配置和操作要提前做好,将 master 节点上面的 $HOME/.kube/config 文件拷贝到 node 节点对应的文件中,安装 kubeadm、kubelet、kubectl,然后执行上面初始化完成后提示的 join 命令即可:

kubeadm join 172.16.1.128:6443 --token abcdef.0123456789abcdef    --discovery-token-ca-cert-hash sha256:deb5158b39948a4592ff48512047ea6e45b288c248872724a28f15008962178b            [preflight] Reading configuration from the cluster...  [preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'  [kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.15" ConfigMap in the kube-system namespace  [kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"  [kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"  [kubelet-start] Activating the kubelet service  [kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...  This 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 control-plane to see this node join the cluster.

如果忘记了上面的 join 命令可以使用命令kubeadm token create –print-join-command重新获取。

执行成功后运行 get nodes 命令:

# kubectl get nodes  NAME         STATUS   ROLES    AGE     VERSION  k8s-master   Ready    master   3d18h   v1.17.2  k8s-node01   Ready    node01   3d18h   v1.17.2  k8s-node02   Ready    node02   3d17h   v1.17.2

可以看到是 NotReady 状态,这是因为还没有安装网络插件,接下来安装网络插件,可以在文档 https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/ 中选择我们自己的网络插件,这里我们安装 calio:

$ wget https://docs.projectcalico.org/v3.8/manifests/calico.yaml

#因为有节点是多网卡,所以需要在资源清单文件中指定内网网卡

$ vi calico.yaml    ......  spec:   containers:   - env:   - name: DATASTORE_TYPE   value: kubernetes   - name: IP_AUTODETECTION_METHOD # DaemonSet中添加该环境变量   value: intertrue"  ......
$ kubectl apply -f calico.yaml # 安装calico网络插件

隔一会儿查看 Pod 运行状态:

# kubectl get pod -n kube-system  NAME                                       READY   STATUS    RESTARTS   AGE  calico-kube-controllers-64d7686ff8-q4wwg   1/1     Running   0          10m  calico-node-92b29                          1/1     Running   0          3d17h  calico-node-f8shx                          1/1     Running   7          3d17h  calico-node-jsk9r                          1/1     Running   0          3d17h  coredns-6cd559f5d5-448x5                   1/1     Running   0          3d18h  coredns-6cd559f5d5-tprrj                   1/1     Running   0          3d18h  etcd-k8s-master                            1/1     Running   1          3d18h  kube-apiserver-k8s-master                  1/1     Running   4          3d18h  kube-controller-manager-k8s-master         1/1     Running   18         3d18h  kube-proxy-7hk2n                           1/1     Running   1          3d18h  kube-proxy-ffslj                           1/1     Running   1          3d17h  kube-proxy-txhcq                           1/1     Running   1          3d18h  kube-scheduler-k8s-master                  1/1     Running   17         3d18h

网络插件运行成功了,node 状态也正常了:

# kubectl get nodes  NAME         STATUS   ROLES    AGE     VERSION  k8s-master   Ready    master   3d18h   v1.17.2  k8s-node01   Ready    node01   3d18h   v1.17.2  k8s-node02   Ready    node02   3d17h   v1.17.2

用同样的方法添加另外一个节点即可。

4. 安装 Dashboard
$ wget https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml  $ vi kubernetes-dashboard.yaml

#修改镜像名称

......  containers:  - args:   - --auto-generate-certificates   image: gcr.azk8s.cn/google_containers/kubernetes-dashboard-amd64:v1.10.1   imagePullPolicy: IfNotPresent  ......

#修改Service为NodePort类型

......  selector:   k8s-app: kubernetes-dashboard  type: NodePort  ......

直接创建:

$ kubectl apply -f kubernetes-dashboard.yaml  $ kubectl get pods -n kube-system -l k8s-app=kubernetes-dashboard  NAME READY STATUS RESTARTS AGE  kubernetes-dashboard-fcfb4cbc-t462n 1/1 Running 0 50m  $ kubectl get svc -n kube-system -l k8s-app=kubernetes-dashboard  NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE  kubernetes-dashboard NodePort 10.110.172.49 <none> 443:32497/TCP 55m

然后可以通过上面的 32497 端口去访问 Dashboard,要记住使用 https,Chrome不生效可以使用Firefox测试。

然后创建一个具有全局所有权限的用户来登录Dashboard:(admin.yaml)

kind: ClusterRoleBinding  apiVersion: rbac.authorization.k8s.io/v1beta1  metadata:   name: admin   annotations:   rbac.authorization.kubernetes.io/autoupdate: "true"  roleRef:   kind: ClusterRole   name: cluster-admin   apiGroup: rbac.authorization.k8s.io  subjects:  - kind: ServiceAccount   name: admin   namespace: kube-system  ---  apiVersion: v1  kind: ServiceAccount  metadata:   name: admin   namespace: kube-system   labels:   kubernetes.io/cluster-service: "true"   addonmanager.kubernetes.io/mode: Reconcile

直接创建:

$ kubectl apply -f admin.yaml  $ kubectl get secret -n kube-system|grep admin-token  admin-token-d5jsg kubernetes.io/service-account-token 3 1d  $ kubectl get secret admin-token-d5jsg -o jsonpath={.data.token} -n kube-system |base64 -d# 会生成一串很长的base64后的字符串

然后用上面的base64解码后的字符串作为token登录Dashboard即可:

最终我们就完成了使用 kubeadm 搭建 v1.17.2 版本的 kubernetes 集群、coredns、ipvs、calico。

配置命令自动补全

yum install -y bash-completion  source /usr/share/bash-completion/bash_completion  source <(kubectl completion bash)  echo "source <(kubectl completion bash)" >> ~/.bashrc

原文出处:coolops -> https://www.coolops.cn/posts/kubeadm-install-single-master-kubernetes/