K8s服务coredns组件报错plugin/loop: Loop (10.244.0.1:45870 -> :53) detected for zone

在部署完成k8s服务后，发现coredns组件状态存在异常，并且日志报错：

[admin@localhost ~]$ kubectl logs --tail 20 -n kube-system coredns-68978987c9-gfq5h
[INFO] plugin/reload: Running configuration MD5 = 2b18e8c07cb255fc312c89e15c1280d3
CoreDNS-1.8.0
linux/amd64, go1.15.3, 054c9ae
[FATAL] plugin/loop: Loop (10.244.0.1:45870 -> :53) detected for zone ".", see https://coredns.io/plugins/loop#troubleshooting. Query: "HINFO 6238558190786240769.4449342423357158470."

解决办法

修改HINFO类型返回

设置返回一个NXDOMAIN的响应码，增加以下内容：

template ANY HINFO . {
            rcode NXDOMAIN
        }

示范：

[root@localhost ~]# kubectl edit cm -n kube-system coredns
    .:53 {
        template ANY HINFO . {
            rcode NXDOMAIN
        }
        errors
        health {
            lameduck 5s
        }
        ready
        kubernetes kubernetes in-addr.arpa ip6.arpa {
          pods insecure
          fallthrough in-addr.arpa ip6.arpa
        }
        prometheus :9153
        forward . /etc/resolv.conf {
          prefer_udp
        }
        cache 30
        loop
        reload
        loadbalance
        hosts /etc/coredns/hosts {
          fallthrough
        }
    }

编辑完成后重启对应pod

参考文档：https://zhuanlan.zhihu.com/p/476611162

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