【k8s】kubeadm快速部署Kubernetes
1.Kubernetes 架构图###
kubeadm是官方社区推出的一个用于快速部署kubernetes集群的工具。 这个工具能通过两条指令完成一个kubernetes集群的部署:
# 创建一个 Master 节点
$ kubeadm init
# 将一个 Node 节点加入到当前集群中
$ kubeadm join <Master节点的IP和端口 >
使用它构建集群时，大致可分为如下几步:
- 在Master及各Node安装Docker、kubelet及kubeadm，并以系统守护进程的方式启动Docker和kubelet服务。
- 在Master节点上通过kubeadminit命令进行集群初始化。
- 各Node通过kubeadmjoin命令加入初始化完成的集群中。
- 在集群上部署网络附件，如flannel或Calico等以提供Service网络及Pod网络。
2.Kubernetes 环境准备###
1⃣️关闭防火墙:
systemctl stop firewalld && systemctl disable firewalld
2⃣️关闭selinux:
sed -i 's/enforcing/disabled/' /etc/selinux/config
setenforce 0
3⃣️关闭swap:
#临时
swapoff -a
#永久关闭swap分区
sudo sed -ri 's/.*swap.*/#&/' /etc/fstab
4⃣️添加主机名与IP对应关系(记得设置主机名):
cat /etc/hosts
10.211.55.3 k8s-master
10.211.55.4 k8s-node1
10.211.55.6 k8s-node2
10.211.55.7 k8s-node3
5⃣️将桥接的IPv4流量传递到iptables的链:
cat > /etc/sysctl.d/k8s.conf << EOF net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF
sysctl --system
3.所有节点安装Docker/kubeadm/kubelet###
Kubernetes默认CRI(容器运行时)为Docker，因此先安装Docker。
1⃣️安装Docker：
sudo su
wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
yum -y install docker-ce-18.06.1.ce-3.el7
systemctl enable docker && systemctl start docker
docker --version
2⃣️添加阿里云YUM软件源：
[root@k8s-master yum.repos.d]# cat /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
3⃣️安装kubeadm，kubelet和kubectl
yum install -y kubelet kubeadm kubectl
systemctl enable kubelet && systemctl start kubelet
4.部署Kubernetes Master###
master节点初始化集群
1⃣️由于默认拉取镜像地址k8s.gcr.io国内无法访问，这里指定阿里云镜像仓库地址。
kubeadm init --apiserver-advertise-address=10.211.55.3 --image-repository registry.aliyuncs.com/google_containers --service-cidr=10.1.0.0/16 --pod-network-cidr=10.244.0.0/16
执行init后：
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 10.211.55.3:6443 --token eehcsb.r8tnvj7ov436x63q \
--discovery-token-ca-cert-hash sha256:583f343b5d55ff96c5a83ccc82444de3c0313adf135d8a980507932aa2f51e1d
如果出错，执行：
[root@k8s-master yum.repos.d]# kubeadm reset
2⃣️使用kubectl工具:
[root@k8s-master yum.repos.d]# mkdir -p $HOME/.kube
[root@k8s-master yum.repos.d]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@k8s-master yum.repos.d]# sudo chown $(id -u):$(id -g) $HOME/.kube/config
[root@k8s-master yum.repos.d]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master NotReady master 8m33s v1.17.0
另外， 提示我们还需要创建网络，并且让其他节点执行kubeadm join...加入集群。
5.创建网络###
如果不创建网络，查看pod状态时，可以看到kube-dns组件是阻塞状态，集群是不可用的：
[root@k8s-master yum.repos.d]# kubectl get pod -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-9d85f5447-n9kkd 0/1 Pending 0 25m
coredns-9d85f5447-s9ms2 0/1 Pending 0 25m
etcd-k8s-master 1/1 Running 0 25m
kube-apiserver-k8s-master 1/1 Running 0 25m
kube-controller-manager-k8s-master 1/1 Running 0 25m
kube-proxy-94wtc 1/1 Running 0 5m41s
kube-proxy-h8q8h 1/1 Running 0 5m45s
kube-proxy-kxmxt 1/1 Running 0 25m
kube-proxy-nxtpq 1/1 Running 0 5m44s
kube-scheduler-k8s-master 1/1 Running 0 25m
master节点部署网络插件fannel
基于kubeadm部署时，flannel同样运行为Kubernetes集群的附件，以Pod的形式部署运行于每个集群节点上以接受Kubernetes集群管理。
事实上，也可以直接将flannel程序包安装并以守护进程的方式运行于集群节点上，即以非托管的方式运行。部署方式既可以是获取其资源配置清单于本地而后部署于集群中，也可以直接在线进行应用部署。
部署命令是“kubectlapply”或“kubectlcreate”，例如，下面的命令将直接使用在线的配置清单进行flannel部署：
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
参考 https://github.com/coreos/flannel
至此master节点就完成了！
[root@k8s-master parallels]# kubectl get cs
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
scheduler Healthy ok
etcd-0 Healthy {"health":"true"}
6.加入Kubernetes Node###
Master各组件运行正常后即可将各Node添加至集群中。
向集群添加新节点，执行在kubeadm init输出的kubeadm join命令:
[root@k8s-node1 yum.repos.d]# kubeadm join 10.211.55.3:6443 --token eehcsb.r8tnvj7ov436x63q \
> --discovery-token-ca-cert-hash sha256:583f343b5d55ff96c5a83ccc82444de3c0313adf135d8a980507932aa2f51e1d
...
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.
查看kubernetes集群状态：
[root@k8s-master parallels]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master Ready master 17h v1.17.0
k8s-node1 Ready <none> 17h v1.17.0
k8s-node2 Ready <none> 17h v1.17.0
k8s-node3 Ready <none> 17h v1.17.0
查看k8s部署过程中用到的镜像：
master节点
[root@k8s-master parallels]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
registry.aliyuncs.com/google_containers/kube-proxy v1.17.0 7d54289267dc 4 days ago 116MB
registry.aliyuncs.com/google_containers/kube-controller-manager v1.17.0 5eb3b7486872 4 days ago 161MB
registry.aliyuncs.com/google_containers/kube-scheduler v1.17.0 78c190f736b1 4 days ago 94.4MB
registry.aliyuncs.com/google_containers/kube-apiserver v1.17.0 0cae8d5cc64c 4 days ago 171MB
registry.aliyuncs.com/google_containers/coredns 1.6.5 70f311871ae1 5 weeks ago 41.6MB
registry.aliyuncs.com/google_containers/etcd 3.4.3-0 303ce5db0e90 6 weeks ago 288MB
quay.io/coreos/flannel v0.11.0-amd64 ff281650a721 10 months ago 52.6MB
registry.aliyuncs.com/google_containers/pause 3.1 da86e6ba6ca1 24 months ago 742kB
Node节点
[root@k8s-node1 parallels]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
registry.aliyuncs.com/google_containers/kube-proxy v1.17.0 7d54289267dc 3 days ago 116MB
quay.io/coreos/flannel v0.11.0-amd64 ff281650a721 10 months ago 52.6MB
registry.aliyuncs.com/google_containers/pause 3.1 da86e6ba6ca1 24 months ago 742kB
