02-kubeadm初始化Kubernetes集群

目录

• 部署
  • 组件分布
  • 部署环境
  • kubeadm 步骤
  • 基础环境
    • 基础配置
  • 安装基础组件
    • 配置yum源
    • 安装组件
• 初始化 master
  • 导入镜像
  • 执行命令：
    • 查看组件状态
    • 查看node状态
  • 安装flannel网络
• 初始化 node
  • 初始化
• master 验证

部署

使用 kubeadm 安装kubernetes集群。

组件分布

部署环境

kubeadm 步骤

1. master, node: 安装 kubelet, kubeadm, docker
2. master: kubeadm init 初始化
3. nodes: kubeadm join 加入集群 参考文章

基础环境

主机名	角色	IP	系统版本	内核版本
master.kubernetes	master	10.0.20.20	CentOS 7.5	5.1.4-1.el7.elrepo.x86_64
node01.kubernetes	node01	10.0.20.21	CentOS 7.5	5.1.4-1.el7.elrepo.x86_64
node02.kubernetes	node02	10.0.20.22	CentOS 7.5	5.1.4-1.el7.elrepo.x86_64
node03.kubernetes	node03	10.0.20.23	CentOS 7.5	5.1.4-1.el7.elrepo.x86_64

基础配置

针对所有机器操作

配置添加hosts

cat /etc/hosts
10.0.20.20 master master.kubernetes
10.0.20.21 node01 node01.kubernetes
10.0.20.22 node02 node02.kubernetes
10.0.20.23 node03 node03.kubernetes

关闭防火墙

systemctl disable firewalld
systemctl stop firewalld

禁用SELINUX

setenforce 0

vi /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

# 执行命令使修改生效
modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf

kube-proxy开启ipvs的前置条件

在 node01，node02 和 node03上执行以下脚本

由于ipvs已经加入到了内核的主干，所以为kube-proxy开启ipvs的前提需要加载以下的内核模块

ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack_ipv4

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
EOF
chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack

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。 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。

如果以上前提条件如果不满足，则即使kube-proxy的配置开启了ipvs模式，也会退回到iptables模式。

安装基础组件

配置yum源

在所有节点上执行

# cat /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes Repo
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
gpgcheck=0

# cat /etc/yum.repos.d/docker-ce.repo
[docker-ce-stable]
name=Docker CE Stable - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/$basearch/stable
enabled=1
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-stable-debuginfo]
name=Docker CE Stable - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/debug-$basearch/stable
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-stable-source]
name=Docker CE Stable - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/source/stable
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-edge]
name=Docker CE Edge - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/$basearch/edge
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-edge-debuginfo]
name=Docker CE Edge - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/debug-$basearch/edge
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-edge-source]
name=Docker CE Edge - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/source/edge
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-test]
name=Docker CE Test - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/$basearch/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-test-debuginfo]
name=Docker CE Test - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/debug-$basearch/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-test-source]
name=Docker CE Test - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/source/test
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-nightly]
name=Docker CE Nightly - $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/$basearch/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-nightly-debuginfo]
name=Docker CE Nightly - Debuginfo $basearch
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/debug-$basearch/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

[docker-ce-nightly-source]
name=Docker CE Nightly - Sources
baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/7/source/nightly
enabled=0
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg

安装组件

在master上执行

yum install docker-ce kubelet kubeadm kubectl -y

# 安装完成后，配置忽略Swap
cat /etc/sysconfig/kubelet
KUBELET_EXTRA_ARGS="--fail-swap-on=false"

在node01 node02 node03 上执行

yum install docker-ce kubelet kubeadm -y

初始化 master

这里都在 master 上操作

说明： 很重要，由于kubeadm 初始化的时候，默认拉取的镜像访问不了，我把master所需要的镜像已经准备好。

可以在 百度云盘地址 提取码：a4z9

导入镜像

先把下载好的镜像上传到master服务器上，然后导入到docker中。

[root@master kubernetes.1.15]# ll
total 869812
-rw------- 1 root root  40542720 Jul  9 13:54 coredns-1.3.tar
-rw------- 1 root root 258365952 Jul  9 13:54 etcd-3.3.tar
-rw------- 1 root root  55390720 Jul  9 15:58 flannel-0.11.tar
-rw------- 1 root root 208382464 Jul  9 14:27 kube-apiserver-1.15.tar
-rw------- 1 root root 160282112 Jul  9 13:53 kube-controller-manager-1.15.tar
-rw------- 1 root root  84278272 Jul  9 13:52 kube-proxy-1.15.tar
-rw------- 1 root root  82671104 Jul  9 13:53 kube-scheduler-1.15.tar
-rw------- 1 root root    754176 Jul  9 13:54 pause-3.1.tar

# 导入镜像
docker load --input coredns-1.3.tar
docker load --input etcd-3.3.tar
docker load --input flannel-0.11.tar
docker load --input kube-apiserver-1.15.tar
docker load --input kube-controller-manager-1.15.tar
docker load --input kube-proxy-1.15.tar
docker load --input kube-scheduler-1.15.tar
docker load --input pause-3.1.tar

执行命令：

[root@master ~]# kubeadm init --kubernetes-version=1.15.0 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=Swap
.....
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 10.0.20.20:6443 --token cgw8vp.c2gw34c6lc2jvw18 \
    --discovery-token-ca-cert-hash sha256:ada6c11ac45aadf7581baab773e7ab172bed8fc0df85ff38299a0c5dcb6538ad

注意 最后会输出上面显示的，这里要保留好，之后添加node的时候，用到的，否则添加不了node

按照初始化最后的提示执行

[root@master ~]# mkdir -p $HOME/.kube
[root@master ~]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

查看组件状态

[root@master ~]# kubectl get cs
NAME                 STATUS    MESSAGE             ERROR
scheduler            Healthy   ok
controller-manager   Healthy   ok
etcd-0               Healthy   {"health":"true"}

查看node状态

[root@master ~]# kubectl get nodes
NAME                STATUS   ROLES    AGE   VERSION
master.kubernetes   NoReady    master   66m   v1.15.0

这里看到master的状态是NoReady，是因为没有安装flannel导致的，下面安装

安装flannel网络

执行：

[root@master ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
podsecuritypolicy.extensions/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

稍等后再次查看master状态

[root@master ~]# kubectl get nodes
NAME                STATUS   ROLES    AGE   VERSION
master.kubernetes   Ready    master   66m   v1.15.0

查看系统命名空间的pods状态

[root@master ~]# kubectl get pods -n kube-system
NAME                                        READY   STATUS    RESTARTS   AGE
coredns-5c98db65d4-8mzfz                    1/1     Running   0          4m
coredns-5c98db65d4-spjx8                    1/1     Running   0          4m6s
etcd-master.kubernetes                      1/1     Running   0          7m24s
kube-apiserver-master.kubernetes            1/1     Running   0          7m23s
kube-controller-manager-master.kubernetes   1/1     Running   0          7m32s
kube-flannel-ds-amd64-wjczq                 1/1     Running   0          48s
kube-proxy-rmckk                            1/1     Running   0          8m14s
kube-scheduler-master.kubernetes            1/1     Running   0          7m33s

此时master已经初始化完成。

初始化 node

同样，先导入node所需的镜像到docker中，然后在执行个初始化命令

本次在node01 node02 node03 上执行

三个node节点操作相同

[root@node01 kubernetes.1.15]# ll
total 612216
-rw------- 1 root root  55390720 Jul  9 15:58 flannel-0.11.tar
-rw------- 1 root root  82671104 Jul  9 13:53 kube-scheduler-1.15.tar
-rw------- 1 root root    754176 Jul  9 13:54 pause-3.1.tar
[root@node01 kubernetes.1.15]# docker image ls
REPOSITORY               TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/kube-proxy    v1.15.0             d235b23c3570        2 weeks ago         82.4MB
quay.io/coreos/flannel   v0.11.0-amd64       ff281650a721        5 months ago        52.6MB
k8s.gcr.io/pause         3.1                 da86e6ba6ca1        18 months ago       742kB

初始化

执行下列命令：

[root@node01 ~]# kubeadm join 10.0.20.20:6443 --token cgw8vp.c2gw34c6lc2jvw18     --discovery-token-ca-cert-hash sha256:ada6c11ac45aadf7581baab773e7ab172bed8fc0df85ff38299a0c5dcb6538ad
[preflight] Running pre-flight checks
	[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[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.

看到上面的最后提示，则表示完成，然后等一会儿后，在master查看效果如下：

master 验证

[root@master ~]# kubectl get nodes
NAME                STATUS   ROLES    AGE   VERSION
master.kubernetes   Ready    master   84m   v1.15.0
node01.kubernetes   Ready    <none>   38m   v1.15.0
node02.kubernetes   Ready    <none>   38m   v1.15.0
node03.kubernetes   Ready    <none>   40m   v1.15.0

[root@master ~]# kubectl get pods -n kube-system
NAME                                        READY   STATUS    RESTARTS   AGE
coredns-5c98db65d4-8mzfz                    1/1     Running   0          80m
coredns-5c98db65d4-spjx8                    1/1     Running   0          80m
etcd-master.kubernetes                      1/1     Running   0          83m
kube-apiserver-master.kubernetes            1/1     Running   0          83m
kube-controller-manager-master.kubernetes   1/1     Running   0          83m
kube-flannel-ds-amd64-4szk7                 1/1     Running   0          40m
kube-flannel-ds-amd64-b4ssp                 1/1     Running   0          38m
kube-flannel-ds-amd64-nmklz                 1/1     Running   0          39m
kube-flannel-ds-amd64-wjczq                 1/1     Running   0          77m
kube-proxy-8fqsz                            1/1     Running   0          39m
kube-proxy-bkrw4                            1/1     Running   0          40m
kube-proxy-n75g8                            1/1     Running   0          38m
kube-proxy-rmckk                            1/1     Running   0          84m
kube-scheduler-master.kubernetes            1/1     Running   0          83m

[root@master ~]# kubectl get ns
NAME              STATUS   AGE
default           Active   85m
kube-node-lease   Active   85m
kube-public       Active   85m
kube-system       Active   85m