kubeadm 是一个工具，通过提供 kubeadm init 和 kubeadm join 来作为创建 Kubernetes 集群的最佳实践“快速路径”。 kubeadm 执行必要的操作来启动并运行一个最小可行集群。按照设计，它只关心引导，而不关心配置机器。使用 kubeadm 作为所有部署的基础，可以更容易地创建一致的集群。
服务器信息
- CPU: 2核 Intel(R) Xeon(R) Platinum 8255C CPU @ 2.50GHz
- 内存: 4GB
- 操作系统: Ubuntu 18.04.1 LTS
- IP地址: 10.206.0.4
确保集群中每台机器 2 GB 以上的内存，内存不足时应用会受限制
主节点至少需要2核CPU
安装Docker
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安装依赖工具
sudo apt-get update sudo apt-get -y install apt-transport-https ca-certificates curl software-properties-common -
安装GPG证书
curl -fsSL https://mirrors.aliyun.com/docker-ce/linux/ubuntu/gpg | sudo apt-key add - -
写入软件源信息
sudo add-apt-repository "deb [arch=amd64] https://mirrors.aliyun.com/docker-ce/linux/ubuntu $(lsb_release -cs) stable" -
安装Docker
sudo apt-get update sudo apt-get -y install docker-ce -
启动Docker
sudo systemctl start docker -
设置开机自启
sudo systemctl enable docker
安装 kubeadm kubelet 和 kubectl
kubeadm是一个快速创建Kubernetes集群的工具,能大大简化Kubernetes集群的部署。有关kubeadm的更多信息，请参阅这里。
- kubeadm : 用于初始化集群。
- kubelet : 用于在集群中的每个节点上用来启动 pod 和 container 等。
- kubectl : 用来与集群通信的命令行工具。
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安装GPG证书
curl https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | sudo apt-key add - -
写入软件源信息
sudo vi /etc/apt/sources.list.d/kubernetes.list写入以下内容
deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main -
安装kubelet kubeadm kubectl
sudo apt-get update sudo apt-get install -y kubelet kubeadm kubectl -
启动kubelet
sudo systemctl start kubelet -
设置kubelet开机自启
sudo systemctl enbale kubelet
初始化Kubernetes集群
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禁用swap
sudo swapoff -a -
拉取gcr镜像
由于Kubernetes所使用的Docker镜像在gcr.io上,国内无法直接访问gcr.io，可通过执行
sudo kubeadm config images pull来测试与gcr.io的连通性。不出意外你会得到如下所示的错误:failed to pull image "k8s.gcr.io/kube-apiserver:v1.17.1": output: Error response from daemon: Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers) , error: exit status 1 To see the stack trace of this error execute with --v=5 or higher大意就是连接超时,无法访问。我们可以通过在国内源下载到这些镜像，然后再打上gcr的tag。这里我写了个脚本,从阿里云镜像仓库下载对应的镜像,然后打上gcr的tag,只需要执行:
curl -sSL https://get.k8s.devzhou.cn/gcr | sudo sh查看本地镜像:
sudo docker images输出如下:
REPOSITORY TAG IMAGE ID CREATED SIZE k8s.gcr.io/kube-controller-manager v1.17.1 5dd8f24429b4 3 days ago 161MB k8s.gcr.io/kube-apiserver v1.17.1 628f0e52ae53 3 days ago 171MB k8s.gcr.io/kube-scheduler v1.17.1 8d2e2e5a92ac 3 days ago 94.4MB k8s.gcr.io/kube-proxy v1.17.1 87a399dffea6 3 days ago 116MB k8s.gcr.io/coredns 1.6.5 70f311871ae1 2 months ago 41.6MB k8s.gcr.io/etcd 3.4.3-0 303ce5db0e90 2 months ago 288MB k8s.gcr.io/pause 3.1 da86e6ba6ca1 2 years ago 742kB -
初始化集群
sudo kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=10.206.0.4由于后面要安装flannel网络插件，所以需要在集群初始化时指定--pod-network-cidr=10.244.0.0/16
--apiserver-advertise-address 参数是 API server 用来告知集群中其它成员的地址，这也是在 init 流程的时候用来构建 kubeadm join 命令行的地址。如果不设置（或者设置为 0.0.0.0）那么将使用默认接口的ip地址。这里我设置为服务器的ip地址。集群初始化成功会输出如下的信息:
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 10.206.0.4:6443 --token 7xh44c.qktgi7gufu0tk4x7 \ --discovery-token-ca-cert-hash sha256:e718166f485fb8f6b56a3fcdc886b9e67fb4d384f9b425a599f458c6a8e5b8bd -
查看集群信息
sudo kubectl get nodes如果出现
The connection to the server localhost:8080 was refused - did you specify the right host or port?则需要进行如下的设置:mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config再次执行
sudo kubectl get nodes，输出如下:NAME STATUS ROLES AGE VERSION vm-0-4-ubuntu NotReady master 6m34s v1.17.1可以看到集群的状态是NotReady，执行下面的命令查看Pod状态:
sudo kubectl get pods -n kube-system -o wide输出如下,可以看到coredns一直处在Pending状态,这一行为是预期之中的，因为系统就是这么设计的。必须完成Pod的网络配置，然后才能完全部署CoreDNS。在网络被配置好之前，DNS 组件会一直处于 Pending 状态。
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES coredns-6955765f44-bsqmw 0/1 Pending 0 9m49s <none> <none> <none> <none> coredns-6955765f44-sdgws 0/1 Pending 0 9m49s <none> <none> <none> <none> etcd-vm-0-4-ubuntu 1/1 Running 0 9m44s 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-apiserver-vm-0-4-ubuntu 1/1 Running 0 9m44s 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-controller-manager-vm-0-4-ubuntu 1/1 Running 0 9m44s 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-proxy-lfrq6 1/1 Running 0 9m49s 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-scheduler-vm-0-4-ubuntu 1/1 Running 0 9m44s 10.206.0.4 vm-0-4-ubuntu <none> <none> -
安装Pod网络插件
以flannel为例:
sudo kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml关于flannel的更多信息请参阅这里
输出如下:
podsecuritypolicy.policy/psp.flannel.unprivileged created clusterrole.rbac.authorization.k8s.io/flannel created clusterrolebinding.rbac.authorization.k8s.io/flannel created serviceaccount/flannel created configmap/kube-flannel-cfg created daemonset.apps/kube-flannel-ds-amd64 created daemonset.apps/kube-flannel-ds-arm64 created daemonset.apps/kube-flannel-ds-arm created daemonset.apps/kube-flannel-ds-ppc64le created daemonset.apps/kube-flannel-ds-s390x created再次执行
sudo kubectl get pods -n kube-system -o wide确保所有Pod都处于Running状态:AMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES kube-system coredns-6955765f44-bsqmw 1/1 Running 0 21m 10.244.0.2 vm-0-4-ubuntu <none> <none> kube-system coredns-6955765f44-sdgws 1/1 Running 0 21m 10.244.0.3 vm-0-4-ubuntu <none> <none> kube-system etcd-vm-0-4-ubuntu 1/1 Running 0 21m 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-system kube-apiserver-vm-0-4-ubuntu 1/1 Running 0 21m 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-system kube-controller-manager-vm-0-4-ubuntu 1/1 Running 0 21m 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-system kube-flannel-ds-amd64-vm742 1/1 Running 0 81s 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-system kube-proxy-lfrq6 1/1 Running 0 21m 10.206.0.4 vm-0-4-ubuntu <none> <none> kube-system kube-scheduler-vm-0-4-ubuntu 1/1 Running 0 21m 10.206.0.4 vm-0-4-ubuntu <none> <none>再次执行
sudo kubectl get nodes，查看集群信息NAME STATUS ROLES AGE VERSION vm-0-4-ubuntu Ready master 24m v1.17.1可以看到集群状态变为Ready，并且角色是master,至此单节点集群搭建成功。
