用kubeadm 搭建 Kubernetes

本文主要是介绍用kubeadm 搭建 Kubernetes，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

记录下这几天在折腾的一个事，就是想把Kubernetes 搭建起来，看看它是怎么玩的，搭建过程还是比较辛苦的，因为没有找到特别靠谱的资料，或者版本不兼容。

一 搭建的方式

Kubernetes 搭建有三种方式，简单评价一下：

1. 基于Docker 本地运行Kubernetes
   先决条件：
   http://www.cnblogs.com/zhangeamon/p/5197655.html
   参考资料：
   https://github.com/kubernetes/community/blob/master/contributors/devel/local-cluster/docker.md
   Install kubectl and shell auto complish:
   评价： 这种方式我没有搭建成功，一直有can not connet 127.0.0.1:8080 的问题，后面感觉是没有创建./kube目录的原因。不过没有再试
2. 用minikube
   minikube是一个适合于在单机环境下搭建，它是创建出一个虚拟机来，并且Kubernetes官方好像已经停止对基于Docker本地运行Kubernetes的支持，参考：https://github.com/kubernetes/minikube， 但是因为它最好要求是virtualbox作为底层虚拟化driver，而我的bare metal 已经安装kvm了，我试了下存在冲突，所以也就没有用这种方式进行安装。
3. 用kubeadm
   它是一个比较方便安装Kubernetes cluster的工具，我也是按照这种方式装成功的。后面会详细记录这种方式。
4. 一步步安装
   每一个组件每一个组件进行安装，我还没有试，可以根据：https://github.com/opsnull/follow-me-install-kubernetes-cluster， 比较麻烦。
   个人还是推荐第三种方式，对于上手来说比较方便一点，我是这几种方式都有尝试。

二 kubeadm setup Kubernetes

参考：
Openstack： https://docs.openstack.org/developer/kolla-kubernetes/deployment-guide.html
Kubernetes： https://kubernetes.io/docs/getting-started-guides/kubeadm/
搭建环境：KVM 起的Centos7 虚拟机
1.Turn off SELinux

sudo setenforce 0
sudo sed -i 's/enforcing/permissive/g' /etc/selinux/config

2.Turn off firewalld

sudo systemctl stop firewalld
sudo systemctl disable firewalld

3.Write the Kubernetes repository file

cat <<EOF > kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=http://yum.kubernetes.io/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
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
sudo mv kubernetes.repo /etc/yum.repos.d

4.Install Kubernetes 1.6.1 or later and other dependencies

sudo yum install -y docker ebtables kubeadm kubectl kubelet kubernetes-cni

5.To enable the proper cgroup driver, start Docker and disable CRI

sudo systemctl enable docker
sudo systemctl start docker

CGROUP_DRIVER=$(sudo docker info | grep "Cgroup Driver" | awk '{print $3}')
sudo sed -i "s|KUBELET_KUBECONFIG_ARGS=|KUBELET_KUBECONFIG_ARGS=--cgroup-driver=$CGROUP_DRIVER --enable-cri=false |g" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
sudo sed -i "s|\$KUBELET_NETWORK_ARGS| |g" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

6.Setup the DNS server with the service CIDR:

sudo sed -i 's/10.96.0.10/10.3.3.10/g' /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

7.reload kubelet

sudo systemctl daemon-reload
sudo systemctl stop kubelet
sudo systemctl enable kubelet
sudo systemctl start kubelet

8.Deploy Kubernetes with kubeadm

sudo kubeadm init --pod-network-cidr=10.1.0.0/16 --service-cidr=10.3.3.0/24

有可能会遇到的问题：如果你是通过公司的proxy出去的网络，那么一定要把你vm的地址放到no_proxy中，否运行kubeadm，会hank在下面， 如果运行失败，执行：sudo kubeadm reset：

[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"
[apiclient] Created API client, waiting for the control plane to become ready

Note:
Note pod-network-cidr is a network private to Kubernetes that the PODs within Kubernetes communicate on. The service-cidr is where IP addresses for Kubernetes services are allocated. There is no recommendation that the pod network should be /16 network in upstream documentation however, the Kolla developers have found through experience that each node consumes an entire /24 network, so this configuration would permit 255 Kubernetes nodes.
运行完后：

[preflight] Starting the kubelet service
[certificates] Generated CA certificate and key.
[certificates] Generated API server certificate and key.
[certificates] API Server serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.122.29]
[certificates] Generated API server kubelet client certificate and key.
[certificates] Generated service account token signing key and public key.
[certificates] Generated front-proxy CA certificate and key.
[certificates] Generated front-proxy client certificate and key.
[certificates] Valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[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"
[apiclient] Created API client, waiting for the control plane to become ready
[apiclient] All control plane components are healthy after 23.768335 seconds
[apiclient] Waiting for at least one node to register
[apiclient] First node has registered after 4.022721 seconds
[token] Using token: 5e0896.4cced9c43904d4d0
[apiconfig] Created RBAC rules
[addons] Created essential addon: kube-proxy
[addons] Created essential addon: kube-dnsYour Kubernetes master has initialized successfully!To start using your cluster, you need to run (as a regular user):sudo cp /etc/kubernetes/admin.conf $HOME/sudo chown $(id -u):$(id -g) $HOME/admin.confexport KUBECONFIG=$HOME/admin.confYou should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:http://kubernetes.io/docs/admin/addons/You can now join any number of machines by running the following on each node
as root:kubeadm join --token 5e0896.4cced9c43904d4d0 192.168.122.29:6443

记住：最后一句话kuberadm join, slave node可以用此CLI去joint到Kubernetes集群中。
然后：

  sudo cp /etc/kubernetes/admin.conf $HOME/sudo chown $(id -u):$(id -g) $HOME/admin.confexport KUBECONFIG=$HOME/admin.conf

Load the kubedm credentials into the system:

mkdir -p $HOME/.kube
sudo -H cp /etc/kubernetes/admin.conf $HOME/.kube/config
sudo -H chown $(id -u):$(id -g) $HOME/.kube/config

运行完后用 去check 状态：

kubectl get nodes
kubectl get pods -n kube-system

9.Deploy CNI Driver
CNI 组网方式：https://linux.cn/thread-15315-1-1.html
用Flannel：
Flannel是基于vxlan， 用vxlan 因为报文长度增加，所以效率相对低，它它是Kubernetes推荐的方式

kubectl apply -f  https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

这种方式我没有成功, flannel 这个pod一直在重启。
用 Canal：

wget http://docs.projectcalico.org/v2.1/getting-started/kubernetes/installation/hosted/kubeadm/1.6/calico.yamlsed -i "s@192.168.0.0/16@10.1.0.0/16@" calico.yaml 
sed -i "s@10.96.232.136@10.3.3.100@" calico.yaml
kubectl apply -f calico.yaml

Finally untaint the node (mark the master node as schedulable) so that PODs can be scheduled to this AIO deployment:

kubectl taint nodes --all=true  node-role.kubernetes.io/master:NoSchedule-

10.restore $KUBELET_NETWORK_ARGS

sudo sed -i "s|\$KUBELET_EXTRA_ARGS|\$KUBELET_EXTRA_ARGS \$KUBELET_NETWORK_ARGS|g" /etc/systemd/system/kubelet.service.d/10-kubeadm.confsudo systemctl daemon-reload
sudo systemctl restart kubeletOLD_DNS_POD=$(kubectl get pods -n kube-system |grep dns | awk '{print $1}')
kubectl delete pod $OLD_DNS_POD -n kube-system

wait for old dns_pod deleted and autorestart a new dns_pod
kubectl get pods,svc,deploy,ds –all-namespaces

11.setup sample application
Ref: http://janetkuo.github.io/docs/getting-started-guides/kubeadm/
Installing a sample application 部分

总结

1. kubectl 自动命令补全
   Ref:https://kubernetes.io/docs/tasks/kubectl/install/

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