# 基础环境设置

Kubernetes 需要一定的环境来保证正常运行，如各个节点时间同步，主机名称解析，关闭防火墙等等。

**主机名称解析**

分布式系统环境中的多主机通信通常基于主机名称进行，这在 IP 地址存在变化的可能 性时为主机提供了固定的访问人口，因此一般需要有专用的 DNS 服务负责解决各节点主机 不过，考虑到此处部署的是测试集群，因此为了降低系复杂度，这里将基于 hosts 的文件进行主机名称解析。

**修改hosts**

分别进入你的，服务器，进入 /etc/hosts 进行编辑

```
vim /etc/hosts

192.168.1.100    master.k8s.io      k8s-vip
192.168.1.101    master01.k8s.io    k8s-master-01
192.168.1.102    master02.k8s.io    k8s-master-02
192.168.1.103    node01.k8s.io      k8s-node-01
192.168.1.104    node02.k8s.io      k8s-node-02
192.168.1.105    harbor.k8s.io      k8s-harbo
```

**修改hostname**

分别进入不同的服务器修改 hostname 名称

```
# 修改 192.168.1.101 服务器
hostnamectl  set-hostname  k8s-master-01
# 修改 192.168.1.102 服务器
hostnamectl  set-hostname  k8s-master-02

# 修改 192.168.1.103 服务器
hostnamectl  set-hostname  k8s-node-01
# 修改 192.168.1.104 服务器
hostnamectl  set-hostname  k8s-node-02
```

**主机时间同步**

将各个服务器的时间同步，并设置开机启动同步时间服务

**关闭防火墙服务**

> 停止并禁用防火墙

```
systemctl start chronyd.service
systemctl enable chronyd.service

systemctl stop firewalld
systemctl disable firewalld
```

**关闭并禁用SELinux**

```
# 若当前启用了 SELinux 则需要临时设置其当前状态为 permissive
setenforce 0

# 编辑／etc/sysconfig selinux 文件，以彻底禁用 SELinux
sed -i 's/^SELINUX=enforcing$/SELINUX=disabled/' /etc/selinux/config

# 查看selinux状态
getenforce 
```

> 如果为permissive，则执行reboot重新启动即可

**禁用 Swap 设备**

kubeadm 默认会预先检当前主机是否禁用了 Swap 设备，并在未用时强制止部署 过程因此，在主机内存资惊充裕的条件下，需要禁用所有的 Swap 设备

```
# 关闭当前已启用的所有 Swap 设备
swapoff -a && sysctl -w vm.swappiness=0
# 编辑 fstab 配置文件，注释掉标识为 Swap 设备的所有行
sed -i 's/.*swap.*/#&/' /etc/fstab
cat /etc/fstab
```

**设置系统参数**

> 设置允许路由转发，不对bridge的数据进行处理

创建 /etc/sysctl.d/k8s.conf 文件

```
vim /etc/sysctl.d/k8s.conf

net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
```

启用br\_netfilter,

```
modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf
ls /proc/sys/net/bridge
```

**资源配置文件**

/etc/security/limits.conf 是 Linux 资源使用配置文件，用来限制用户对系统资源的使用

```
echo "* soft nofile 65536" >> /etc/security/limits.conf
echo "* hard nofile 65536" >> /etc/security/limits.conf
echo "* soft nproc 65536"  >> /etc/security/limits.conf
echo "* hard nproc 65536"  >> /etc/security/limits.conf
echo "* soft  memlock  unlimited"  >> /etc/security/limits.conf
echo "* hard memlock  unlimited"  >> /etc/security/limits.conf
```

> 自centos7.3 以后，普通用户登录，会被/etc/security/limits.d/20-nproc.conf文件覆盖，需要在修改一下此文件
>
> ```
> echo "* soft nofile 65536" >> /etc/security/limits.d/20-nproc.conf
> echo "* hard nofile 65536" >> /etc/security/limits.d/20-nproc.conf
> echo "* soft nproc 65536"  >> /etc/security/limits.d/20-nproc.conf
> echo "* hard nproc 65536"  >> /etc/security/limits.d/20-nproc.conf
> echo "* soft  memlock  unlimited"  >> /etc/security/limits.d/20-nproc.conf
> echo "* hard memlock  unlimited"  >> /etc/security/limits.d/20-nproc.conf
> ```

**安装依赖包以及相关工具**

```
yum install -y epel-release
yum install -y yum-utils device-mapper-persistent-data lvm2 net-tools conntrack-tools wget vim  ntpdate libseccomp libtool-ltdl
```


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