linux CoreDns安装

k8s coredns安装介绍：
https://kubernetes.io/zh/docs/tasks/administer-cluster/coredns/

1.下载二进制文件

wget https://github.com/coredns/coredns/releases/download/v1.5.0/coredns_1.5.0_linux_amd64.tgz
tar zxf coredns_1.5.0_linux_amd64.tgz -C /usr/bin/

2.创建用户

useradd coredns -s /sbin/nologin

3.编辑/etc/coredns/Corefile

.:53 {
  # 绑定interface ip
  bind 127.0.0.1
  # 先走本机的hosts
  # https://coredns.io/plugins/hosts/
  hosts {
    # 自定义sms.service search.service 的解析
    # 因为解析的域名少我们这里直接用hosts插件即可完成需求
    # 如果有大量自定义域名解析那么建议用file插件使用 符合RFC 1035规范的DNS解析配置文件
    10.6.6.2 sms.service
    10.6.6.3 search.service
    # ttl
    ttl 60
    # 重载hosts配置
    reload 1m
    # 继续执行
    fallthrough
  }
  # file enables serving zone data from an RFC 1035-style master file.
  # https://coredns.io/plugins/file/
  # file service.signed service
  # 最后所有的都转发到系统配置的上游dns服务器去解析
  forward . /etc/resolv.conf
  # 缓存时间ttl
  cache 120
  # 自动加载配置文件的间隔时间
  reload 6s
  # 输出日志
  log
  # 输出错误
  errors
}

更新插件使用：https://github.com/coredns/coredns

4.编辑/usr/lib/systemd/system/coredns.service

[Unit]
Description=CoreDNS DNS server
Documentation=https://coredns.io
After=network.target

[Service]
PermissionsStartOnly=true
LimitNOFILE=1048576
LimitNPROC=512
CapabilityBoundingSet=CAP_NET_BIND_SERVICE
AmbientCapabilities=CAP_NET_BIND_SERVICE
NoNewPrivileges=true
User=coredns
ExecStart=/usr/bin/coredns -conf=/etc/coredns/Corefile
ExecReload=/bin/kill -SIGUSR1 $MAINPID
Restart=on-failure

[Install]
WantedBy=multi-user.target

5.启动coredns

systemctl enable coredns
systemctl start coredns
systemctl status coredns

生产配置

s]# cat corefile.conf
.:53 {
    bind 192.168.44.218
    errors
    log
    loadbalance round_robin
    health {
       lameduck 5s
    }
    hosts {
     192.168.44.218 apollo.config.beta
     192.168.6.166  apollo.config.beta
     192.168.6.166  apollo.beta
     192.168.44.218  apollo.beta
     192.168.44.210 BETAWS26
     192.168.44.203 BDSGATEWAY
     192.168.1.21 HOSTBETAWS21
     192.168.6.158 HOSTBETAAS21
     192.168.6.159 HOSTBETAAS22
     192.168.6.164 HOSTBETAWS22
     192.168.44.201 HOSTBETAWS24
     192.168.44.203 HOSTBETAWS25
     192.168.44.204 HOSTBETADS21
     192.168.1.21 HOSTMONGODB
     192.168.44.201 HOSTMONGODBWS4
     192.168.44.203 HOSTMONGODBWS5
     192.168.44.204 HOSTREDIS
     192.168.45.0 HOSTAUTH
     192.168.44.210 HOSTBIGDATASERVICE
     192.168.44.210 HOSTAUTOCOMPLETE
     192.168.44.210 HOSTUSERSUBSCRIBE
     192.168.44.210 abcba.com
     192.168.45.0 w-1.betawm.com
     192.168.45.0 w-2.betawm.com
     192.168.45.0 HOSTTEST
     ttl 50
     reload 1m
     fallthrough
    }
    ready
    prometheus :9153
    forward . 100.100.2.136 100.100.2.138
    cache 30
    reload
}
[root@BETAWS27 coredns]# ps aux | grep coredns
root     1315411  0.7  0.2 753292 39416 ?        Sl   Sep11 1016:14 /beta/coredns/coredns -conf /beta/coredns/corefile.conf
root     2014857  0.0  0.0  12108  1044 pts/0    S+   09:57   0:00 grep --color=auto coredns