CoreDNS+Etcd实现自动增加A记录

小知识，大挑战！本文正在参与“程序员必备小知识”创作活动
说明:因公司有频繁私有化部署需求，CI跑完后还需要手动在Bind9增加A记录，现使用CoreDNS+Etcd做内部DNS服务器，在部署任务完成后，部署工具根据jira提交内容完成Etcd数据插入

环境说明

• Etcd使用Yum安装
• CoreDNS

大体步骤

1. 安装etcd
2. 安装coredns
3. coredns使用etcd作为数据来源

实施

1. 安装etcd

yum install -y etcd
systemctl start etcd
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2. 安装coredns

# 编写systemd文件
vim /etc/systemd/system/coredns.service
[Unit]
Description=CoreDNS
After=network.target
After=network-online.target
Wants=network-online.target

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

[Install]
WantedBy=multi-user.target
# 下载coredns
wget https://github.com/coredns/coredns/releases/download/v1.8.4/coredns_1.8.4_linux_amd64.tgz
tar zxf coredns_1.8.4_linux_amd64.tgz -C /usr/bin/

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3. coredns配置

新建/etc/coredns/Corefile文件

.:53 {
    health
    log
    errors
    cache 30
    reload 10s
    forward . 223.5.5.5 8.8.8.8

}
hive-intel.qa:53 {
    etcd {
        stubzones
        path /coredns
        endpoint http://127.0.0.1:2379  #etcd地址:端口
        upstream 223.5.5.5:53 8.8.8.8:53 /etc/resolv.conf
    }
    template IN A hicloud.hive-intel.qa {
      match .*\.hicloud\.hive-intel\.qa
      answer "{{ .Name }} 60 IN A 172.168.1.224"
      fallthrough
    }
    template IN A testhicloud.hive-intel.qa {
      match .*\.testhicloud\.hive-intel\.qa
      answer "{{ .Name }} 60 IN A 172.168.1.224"
      fallthrough
    }
    health
    log
    errors
    cache 30
    reload 10s
}
hive-intel.devop:53 {
    etcd {
        stubzones
        path /coredns
        endpoint http://127.0.0.1:2379
        upstream 223.5.5.5:53 8.8.8.8:53 /etc/resolv.conf
    }
    template IN A hicloud.hive-intel.devop {
      match .*\.hicloud\.hive-intel\.devop
      answer "{{ .Name }} 60 IN A 172.168.1.224"
      fallthrough
    }
    health
    log
    errors
    cache 30
    reload 10s
}
localserver.hivetech.iego.net:53 {
    etcd {
        stubzones
        path /coredns
        endpoint http://127.0.0.1:2379 
        upstream 223.5.5.5:53 8.8.8.8:53 /etc/resolv.conf
    }
    health
    log
    errors
    cache 30
    reload 10s
}


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4. 启动

systemctl enable coredns
systemctl start coredns
systemctl status coredns
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