kubernetes 1.18集群安装-轻识

准备环境

本次实验以k8s 1.8版本为例：

kubelet-1.18.0-0：在集群中的每个节点上用来启动 Pod 和容器等
kubeadm-1.18.0-0：在集群中的每个节点上用来启动 Pod 和容器等
kubectl-1.18.0-0：用来与集群通信的命令行工具
docker-19.03.13-ce：k8s基于docker拉取镜像、启动服务

准备两台Linux服务器（CentOS系统）：

控制节点：10.0.0.1，安装docker、kubelet、kubectl和kubeadm
worker节点：10.0.0.2，安装docker、kubelet、kubectl和kubeadm

控制节点操作

安装docker

sudo yum install docker sudo systemctl start docker

配置kubernetes镜像地址

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo[kubernetes]name=Kubernetesbaseurl=http://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64enabled=1gpgcheck=1repo_gpgcheck=1gpgkey=http://packages.cloud.google.com/yum/doc/yum-key.gpg http://packages.cloud.google.com/yum/doc/rpm-package-key.gpgEOF

禁用SELinux，为了允许容器访问主机文件系统，这么操作是为了保证后续 Pod 网络工作正常

setenforce 0sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

Kubernetes 1.8开始要求关闭系统的Swap，如果不关闭，默认配置下kubelet将无法启动

swapoff -a

安装kubeadm、kubelet、kubectl

sudo yum install -y kubeadm-1.18.0-0 kubelet-1.18.0-0 kubectl-1.18.0-0  --disableexcludes=kubernetes

查看kubeadm是否安装成功

$ kubeadm versionkubeadm version: &version.Info{Major:"1", Minor:"8", GitVersion:"v1.8.0", GitCommit:"9befc2b8928a9426501d3bf62f72849d5cbcd5a3", GitTreeState:"clean", BuildDate:"2017-11-20T05:17:43Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/amd64"}

通过systemctl 启动kubelet

#启动kubeletsudo systemctl start kubelet#显示日志：Warning: kubelet.service changed on disk. Run 'systemctl daemon-reload' to reload units.# 重载所有修改过的配置文件sudo systemctl daemon-reload#开机启动kubeletsudo systemctl enable kubelet

必须保证kubelet安装成功，执行下面命令不能报错

$ kubelet version

初始化kubeadm

#重置kubeadm的初始化sudo kubeadm reset# –-pod-network-cidr：用于指定Pod的网络范围，物理机ip地址，10.99必须是存在的物理机ip地址# –-service-cidr：用于指定service的网络范围，虚拟ip地址# --feature-gates：在 Kubernetes 1.18 中，用 kubeadm 来安装 kube-dns 这一做法已经被废弃sudo kubeadm init --kubernetes-version=v1.18.0 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.1.0.0/16

执行初始化后，可以在初始化的日志中看到，需要在集群其他机器中执行的命令

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 10.0.0.1:6443 --token wzghpa.mwvdt4ho0fn936dg \    --discovery-token-ca-cert-hash sha256:aa101787f7398ac95755b1e61aa56c69cbf7205d5035184622ba8cad57abf3e1

在控制节点中配置kube相关的配置，并且export配置

mkdir -p $HOME/.kubesudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/configsudo chown $(id -u):$(id -g) $HOME/.kube/configexport KUBECONFIG=$HOME/.kube/config

执行完上述命令后，通过kubectl version查看kubectl 是否安装成功，能正常显示出Client Version和Server Version等信息，即表示kubectl 集群安装成功了，只是目前集群中只有控制节点

$ kubectl versionClient Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.0", GitCommit:"9e991415386e4cf155a24b1da15becaa390438d8", GitTreeState:"clean", BuildDate:"2020-03-25T14:58:59Z", GoVersion:"go1.13.8", Compiler:"gc", Platform:"linux/amd64"}Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.0", GitCommit:"9e991415386e4cf155a24b1da15becaa390438d8", GitTreeState:"clean", BuildDate:"2020-03-25T14:50:46Z", GoVersion:"go1.13.8", Compiler:"gc", Platform:"linux/amd64"}

查看集群节点

#查看集群节点$ kubectl get nodeNAME          STATUS     ROLES    AGE   VERSIONmaster   NotReady   master   14h   v1.18.0#查看命名空间$ kubectl get ns NAME              STATUS   AGEdefault           Active   15hkube-node-lease   Active   15hkube-public       Active   15hkube-system       Active   15h

kubectl 安装成功后，需要为集群部署flannel网络，执行完成以后，可以看到创建的一些配置

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.ymlpodsecuritypolicy.policy/psp.flannel.unprivileged createdclusterrole.rbac.authorization.k8s.io/flannel createdclusterrolebinding.rbac.authorization.k8s.io/flannel createdserviceaccount/flannel createdconfigmap/kube-flannel-cfg createddaemonset.apps/kube-flannel-ds created

在命名空间kube-system中查看kube-flannel的pod是否启动成功

$ kubectl get pod -n kube-system | grep kube-flannelkube-flannel-ds-hgkk6                 0/1     Init:ImagePullBackOff   0          15m

看到kube-flannel没有启动成功，原因是kube-flannel的镜像没有下载下来，需要手动下载对应的kube-flannel版本

$ wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

将kube-flannel.yml下载到服务器上后，查看yml中使用的flannel版本

$ cat kube-flannel.ymlcontainers:  - name: kube-flannel    image: quay.io/coreos/flannel:v0.13.1-rc2

看到kube-flannel使用的镜像是quay.io/coreos/flannel:v0.13.1-rc2，通过docker命令下载镜像

$ sudo docker pull quay.io/coreos/flannel:v0.13.1-rc2$ sudo docker image ls | grep flannelquay.io/coreos/flannel    v0.13.1-rc2         dee1cac4dd20        7 weeks ago         64.3MB

flannel镜像下载下来后，kube-flannel的pod就自动启动成功了

$ kubectl get pod -n kube-system | grep kube-flannelkube-flannel-ds-hgkk6                 1/1     Running   0          6m

添加worker节点

安装docker

sudo yum install docker sudo systemctl start docker

配置kubernetes镜像地址

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo[kubernetes]name=Kubernetesbaseurl=http://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64enabled=1gpgcheck=1repo_gpgcheck=1gpgkey=http://packages.cloud.google.com/yum/doc/yum-key.gpg http://packages.cloud.google.com/yum/doc/rpm-package-key.gpgEOF

禁用SELinux，为了允许容器访问主机文件系统，这么操作是为了保证后续 Pod 网络工作正常

setenforce 0sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

Kubernetes 1.8开始要求关闭系统的Swap，如果不关闭，默认配置下kubelet将无法启动

swapoff -a

安装kubeadm、kubelet

sudo yum install -y kubeadm-1.18.0-0 kubelet-1.18.0-0 --disableexcludes=kubernetes

通过systemctl 启动kubelet

#启动kubeletsudo systemctl start kubelet#显示日志：Warning: kubelet.service changed on disk. Run 'systemctl daemon-reload' to reload units.# 重载所有修改过的配置文件sudo systemctl daemon-reload#开机启动kubeletsudo systemctl enable kubelet

接下来，需要将worker服务器，加入到k8s集群中，在worker节点服务器执行命令

$ sudo kubeadm join 10.0.0.1:6443 --token wzghpa.mwvdt4ho0fn936dg \    --discovery-token-ca-cert-hash sha256:aa101787f7398ac95755b1e61aa56c69cbf7205d5035184622ba8cad57abf3e1

如果执行过程中，出现以下错误信息

[preflight] Some fatal errors occurred:    /var/lib/kubelet is not empty[preflight] If you know what you are doing, you can skip pre-flight checks with `--skip-preflight-checks`

则需要重置kubeadm，重置后，会删除/var/lib/kubelet下面的一些文件

$ sudo kubeadm reset

重置以后，重新执行kubeadm join命令，将worker节点加入到集群中

$ sudo kubeadm join 10.0.0.1:6443 --token wzghpa.mwvdt4ho0fn936dg \    --discovery-token-ca-cert-hash sha256:aa101787f7398ac95755b1e61aa56c69cbf7205d5035184622ba8cad57abf3e1#日志输出[preflight] Starting the kubelet service[discovery] Trying to connect to API Server "10.0.0.1:6443"[discovery] Created cluster-info discovery client, requesting info from "https://10.0.0.1:6443"[discovery] Requesting info from "https://10.0.0.1:6443" 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 "10.0.0.1:6443"[discovery] Successfully established connection with API Server "10.0.0.1:6443"[bootstrap] Detected server version: v1.18.4[bootstrap] The server supports the Certificates API (certificates.k8s.io/v1beta1)
Node join complete:* Certificate signing request sent to master and response  received.* Kubelet informed of new secure connection details.
Run 'kubectl get nodes' on the master to see this machine join

到此位置，就将worker节点加入了集群，最后到控制节点去执行命令，即可看到集群中的node节点

$ kubectl get nodesNAME                            STATUS   ROLES    AGE   VERSIONnode1                           Ready    <none>   17s   v1.18.0master                          Ready    master   19h   v1.18.0

若后续还需要向集群里添加服务器，则按照worker节点安装的流程操作即可