我已经使用kubeadm在具有法兰绒（v0.11.0-amd64）的一台服务器（不是VM）上安装了Kubernetes（1.17.3）。然后，我安装了grafana和prometheus，并且可以在NodePort http://<serverip>:31000
现在，当我尝试从grafana访问prometheus服务时，其给出错误Could not resolve host: prometheus-server;
我开始进行故障排除并执行以下步骤
确认已配置podsCIDR
kubectl get nodes -o jsonpath='{.items[*].spec.podCIDR}'
10.244.0.0/24
IP和DNS服务名称上的卷曲
# curl 10.244.0.33:9090
<a href="/prometheus/graph">Found</a>
# curl 10.109.215.27:9090
<a href="/prometheus/graph">Found</a>
# curl http://prometheus-server:9090
curl: (6) Could not resolve host: prometheus-server; Unknown error
我的/etc/resolv.conf为空，我在条目下方添加了内容，但仍然没有成功
search cluster.local
nameserver <IP of Server>
以下是CoreDNS日志的输出
kubectl logs -f coredns-6955765f44-cnhtz -n kube-system
.:53
[INFO] plugin/reload: Running configuration MD5 = 4e235fcc3696966e76816bcd9034ebc7
CoreDNS-1.6.5
linux/amd64, go1.13.4, c2fd1b2
[ERROR] plugin/errors: 2 2339874627451903403.2757028323724952357. HINFO: read udp 10.244.0.13:38879->8.8.4.4:53: read: no route to host
[ERROR] plugin/errors: 2 2339874627451903403.2757028323724952357. HINFO: read udp 10.244.0.13:53266->8.8.4.4:53: i/o timeout
[ERROR] plugin/errors: 2 2339874627451903403.2757028323724952357. HINFO: read udp 10.244.0.13:37289->8.8.8.8:53: i/o timeout
[ERROR] plugin/errors: 2 2339874627451903403.2757028323724952357. HINFO: read udp 10.244.0.13:44281->8.8.4.4:53: read: no route to host
更新1：
响应@KoopaKiller 我运行curl http://prometheus-server:9090吗？来自主机和grafana pod的消息（来自grafana pod的消息表明它对IP没有响应）。 我用清单安装了prometheus和grafana，它们都在同一个命名空间中。
kubectl get pods -A
NAMESPACE NAME READY STATUS
kube-system coredns-6955765f44-cnhtz 1/1 Running
kube-system coredns-6955765f44-d9wrj 1/1 Running
kube-system kube-flannel-ds-amd64-rbsbv 1/1 Running
kube-system kube-proxy-nblnq 1/1 Running
monitoring-logging grafana-b57ccddf9-p7w2q 1/1 Running
monitoring-logging prometheus-server-65d7dc7999-frd8k 2/2 Running
我在coredns事件中观察到的另一件事是丢失了文件“ /run/flannel/subnet.env”，但该文件可用，看起来每次重新启动时都会重新创建，而CoreDNS却发现得很晚。
Events:
Type Reason Message
---- ------ -------
Warning FailedCreatePodSandBox Failed to create pod sandbox: rpc error: code = Unknown desc = failed to set up sandbox container "d69af6411310ae3c4865a3ddce0667a40092b0dcf55eb5f8ddb642e503dcc0c5" network for pod "coredns-6955765f44-d9wrj": networkPlugin cni failed to set up pod "coredns-6955765f44-d9wrj_kube-system" network: open /run/flannel/subnet.env: no such file or directory
Warning FailedCreatePodSandBox Failed to create pod sandbox: rpc error: code = Unknown desc = failed to set up sandbox container "b6199b3ce4a769c0ccfef6f247763beb1ca0231de52f6309d2b2f122844746ee" network for pod "coredns-6955765f44-d9wrj": networkPlugin cni failed to set up pod "coredns-6955765f44-d9wrj_kube-system" network: open /run/flannel/subnet.env: no such file or directory
Normal SandboxChanged Pod sandbox changed, it will be killed and re-created.
Warning FailedCreatePodSandBox Failed to create pod sandbox: rpc error: code = Unknown desc = failed to set up sandbox container "097dbf97858d8ea3510e8337eb9b0bc8baf966ab51a2a56971e8ae54c5b516a6" network for pod "coredns-6955765f44-d9wrj": networkPlugin cni failed to set up pod "coredns-6955765f44-d9wrj_kube-system" network: open /run/flannel/subnet.env: no such file or directory
Normal Pulled Container image "k8s.gcr.io/coredns:1.6.5" already present on machine
Normal Created Created container coredns
Normal Started Started container coredns
Update2： 我按照链接调试DNS，并显示了结果
kubectl exec -ti dnsutils -- nslookup kubernetes.default
kubectl exec dnsutils cat /etc/resolv.conf
然后我将日志插件添加到CoreDNS配置中，并意识到CoreDNS没有接收到任何DNS查询，我禁用了我的防火墙，并且一切都按预期开始工作，但是为什么它不能与防火墙一起工作，所以我的开放端口在后面，它有端口也有法兰绒
firewall-cmd --list-ports
6443/tcp 2379-2380/tcp 10250/tcp 10251/tcp 10252/tcp 30000-32767/tcp 8080/tcp 8443/tcp 8285/udp 8472/udp 502/tcp
答案 0 :(得分：2)
要使其工作而不禁用防火墙，我必须添加以下规则，所有内容均以dnsnames开始工作
firewall-cmd --add-masquerade --permanent
firewall-cmd --reload
systemctl restart firewalld
我从下面的链接中得到了提示，但是会详细研究为什么我们需要它吗？
How can I use Flannel without disabing firewalld (Kubernetes)