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04.安装kuburnet并初始化master节点和node节点

本文的内容说明以下6点:
  • 1 什么是kuburnetes？
  • 2 安装kuburnetes需要什么条件?
  • 3 初始化kuburnetes并启动它
  • 4 说明master节点的作用，并基于已经安装好的kuburnetes初始化它
  • 5 初始化node节点
  • 6 总结下

1 什么是kuburnetes?​

这是来自官方解释
Kubernetes 是一个可移植的、可扩展的开源平台，用于管理容器化的工作负载和服务，可促进声明式配置和自动化。

用一个交响乐团来比喻,kuburentes则是指挥家，而各个基本的容器服务则是乐手,指挥家负责指挥各组乐手的工作， 而各组乐手则配合好被指挥的工作，从而合奏出恢弘震撼心灵的乐章。

2 安装kuburnetes需要什么条件?​

需要满足以下3个条件
  • 关闭系统的swap交换区 原因是:磁盘io瓶颈会影响kuburnetes的性能。
  • 关闭Selinux 原因是selinux出于安全的原因可能会限制kuburnetes对文件的操作,造成kuburnetes的执行操作时失败
  • 安装容器依赖,kuburnetes的调度的基本粒度是容器，而容器需要自己安装，本文则选用docker作为kuburnetes 的底层容器驱动

2.1 禁用swap交换区​

临时禁用

swapoff -a

如果想下次重启机器还是生效的话，则 /etc/fstab

 #
 # /etc/fstab
 # Created by anaconda on Mon Jan 22 14:43:31 2018
 #
 # Accessible filesystems, by reference, are maintained under '/dev/disk'
 # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
 #
 UUID=4fb2f21e-8b37-4461-9163-eced787a0565 /                       xfs     defaults        0 0
// highlight-start
 # /www/swap    swap    swap    defaults    0 0 # 找下有没有类似 /**/* swap 这种格式的并注释它
// highlight-end
...

2.2 禁用Selinux​

临时禁用

setenforce 0

如果想以后默认禁用Selinux,则: /etc/sysconfig/selinux

  # This file controls the state of SELinux on the system.
  # SELINUX= can take one of these three values:
  #     enforcing - SELinux security policy is enforced.
  #     permissive - SELinux prints warnings instead of enforcing.
  #     disabled - No SELinux policy is loaded.
// highlight-start
  SELINUX=disabled # 这里修改为disable
// highlight-end 
  # SELINUXTYPE= can take one of three two values:
  #     targeted - Targeted processes are protected,
  #     minimum - Modification of targeted policy. Only selected processes are protected.
  #     mls - Multi Level Security protection.
  SELINUXTYPE=targeted

2.3 安装docker​

$ sudo yum -y install yum-utils # yum源配置管理工具 用于下面添加国内源用的
$ sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo # 添加国内镜像源
$ sudo yum -y install docker-ce # 安装docker
$ sudo systemctl startg docker # 启动docker 
$ sudo systemctl enable docker # 开机启动

3 安装kuburnetes并启动它​

3.1 添加国内的安装源​

/etc/yum.repos.d/kubernetes.repo

$ cat <<EOF > /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
EOF

3.2 安装​

$ sudo yum install -y kubelet kubeadm kubectl # 安装需要的工具
$ sudo systemctl enable kubelet && systemctl start kubelet # 启动kuburnetes
kubelet,kubeadm和kubectl说明
  • kubelete就是kuburnet服务进程，不管是master节点还是node节点，都有它，kuburnetes的容器服务启动和关闭就是被这个进程控制的
  • kubeadm 是用来初始化节点用的命令行工具，如初始化配置以及把节点加入集群中
  • kubectl 是用来与kubelete通信用的命令行工具，通过这个工具把指令发送给kubelete就能达到对集群的调度目的 :::

现在机子已经安装好kuburnenetes，但它还不能用，需要后面初始化为master节点或node节点，才能加入集群中发挥作用 :::

4 说明master节点的作用并基于已经安装好的kuburnetes初始化它​

master是整个集群服务的控制中心，它扮寅着一个指挥家，其它作用是控制集群下的所有node节点。

4.1 修改主机名​

$ hostnamectl set-hostname  master

4.2 配置默认网卡的ip解析向master​

显示默认网卡名

$ ip route
// highlight-start
default via 172.17.0.1 dev eth0 proto dhcp metric 100 #etho 则是默认网卡
// highlight-end
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
172.18.208.0/20 dev eth0 proto kernel scope link src 172.18.212.208 metric 100

找出eth0网卡的ip

docker0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255
ether 02:42:f0:e3:0d:03  txqueuelen 0  (Ethernet)
RX packets 0  bytes 0 (0.0 B)
RX errors 0  dropped 0  overruns 0  frame 0
TX packets 0  bytes 0 (0.0 B)
TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 172.18.212.208 netmask 255.255.240.0 broadcast 172.18.223.255 inet6 fe80::216:3eff:fe0e:99eb prefixlen 64 scopeid 0x20 ether 00:16:3e:0e:99:eb txqueuelen 1000 (Ethernet) RX packets 185734 bytes 90445765 (86.2 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 212763 bytes 26463552 (25.2 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0


>找出默认网卡的ip后添加本地解析

``` bash 
echo "172.18.212.208 master" >> /etc/hosts

4.3 配置Kubernetes初始化配置​

用kubeadm工具执行kubeadm config print init-defaults > init-kubeadm.yaml会在当前目录生成一个init-kubeadm.yaml的配置。内容为:

init-kubeadm.yaml

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 1.2.3.4
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: node
  taints: null
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: k8s.gcr.io
kind: ClusterConfiguration
kubernetesVersion: 1.21.0
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
scheduler: {}

需要修改下其中的ip为本机的默认网卡ip以及由于国内网络的原因，需要修改下其它的配置,修改后的结果为: init-kubeadm.yaml

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 172.18.212.205
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: master
  taints: null
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
  # coredns这个镜像国内不好下载，所以专门配置镜像源下载
  imageRepository: swr.cn-east-2.myhuaweicloud.com/coredns
  imageTag: 1.8.0
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/k8sxio
kind: ClusterConfiguration
kubernetesVersion: 1.21.0
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
  # 这里子网
  podSubnet: 10.244.0.0/16
scheduler: {}

4.4 拉取节点需要的镜像​

$ kubeadm config images pull --config init-kubeadm.yaml
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-apiserver:v1.21.0
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-controller-manager:v1.21.0
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-scheduler:v1.21.0
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-proxy:v1.21.0
[config/images] Pulled registry.aliyuncs.com/k8sxio/pause:3.4.1
[config/images] Pulled registry.aliyuncs.com/k8sxio/etcd:3.4.13-0
[config/images] Pulled swr.cn-east-2.myhuaweicloud.com/coredns/coredns:1.8.0

4.5 初始化master节点​

$ kubeadm init --config init-kubeadm.yaml
[init] Using Kubernetes version: v1.21.0
...
Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

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:

// highlight-start kubeadm join 172.18.212.205:6443 --token abcdef.0123456789abcdef \ --discovery-token-ca-cert-hash sha256:b68e69e6d7de096c221b19a2d4e612ad177d2698942c2ad334283694efa443a7 // highlight-end $ mkdir -p $HOME/.kube # 根据上面安装成功的提示执行这些命令能初始master节点 $ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config $ sudo chown $(id -u):$(id -g) $HOME/.kube/config

根据初始化master节点成功后打印出来的提示，在`mster`节点还需要运行这几条命令
``` bash
 $  mkdir -p $HOME/.kube
 $  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
 $  sudo chown $(id -u):$(id -g) $HOME/.kube/config

另一部分的提示為:

这个用于子节点加入时用的命令

$ kubeadm join 172.18.212.205:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:b68e69e6d7de096c221b19a2d4e612ad177d2698942c2ad334283694efa443a7
提示

如果加入master节点的token丢失，则在想要加入的master节点中运行kubeadm token create --print-join-command则又会生成新的的， 加入命令了, 在还未加入master的node节点中运行会自动加入进来，命令生成如下:

生成新的token

$ kubeadm token create --print-join-command
kubeadm join 192.168.0.200:6443 --token 2avj3a.d7cxe3a6qldhiqoi --discovery-token-ca-cert-hash sha256:eedb176c6faabf50ae75c8a15fdd129004caa4a1f08cf18420bc08a263fbc072

4.6 安装flannel​

kuburnetes的pod网络是必要的。而plannel就是这个作用，plannel的安装启动本质就是一个kuburnetes集群，只要把配置文件下载 下来然后下载对应的镜像下来，用kubectl启动它就可以了。

4.6.1 下载flannel配置​

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

4.6.2 拉取启动flannel需要的镜像​

打开下载好的kube-flannel.yml当中有一个image字段是启动flannel必要的镜像,如:

...
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
// highlight-start
        image: quay.io/coreos/flannel:v0.14.0
// highlight-end
        command:
        ...

把启动flannel镜像拉取下来

$ docker pull quay.io/coreos/flannel:v0.14.0

4.6.3 启动flannel​

$ kubectl apply -f kube-flannel.yml

5 master初始化成功小结​

到了这一步，master就成功初始化完成了，输入:

获取节点状态

$ kubectl get nodes
NAME     STATUS   ROLES                  AGE   VERSION
master   Ready    control-plane,master   25m   v1.21.3 # <-- 看master 节点已经准备好了
提示

如果您启动flannel后，获取的master状态还不是Ready状态而是NotReady的话，那么请等一等，启动flannel也是需要时间的。

6 初始化node`节点​

找一台新的机子， 机子能直接访问master节点，要在同一个局域网中， 按上面的步骤2-3把docker和kuburnetes安装好。

6.1 设置主机名​

hostnamectl set-hostname node_1

6.2 把配置从master中传过来​