我正在尝试将kube集群从Ubuntu 16升级到18。升级后，kube-dns pod不断崩溃。如果我要回滚到U16，问题只会出现在U18上。
Kube版本“ v1.10.11”
kube-dns pod事件：
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 28m default-scheduler Successfully assigned kube-dns-75966d58fb-pqxz4 to
Normal SuccessfulMountVolume 28m kubelet, MountVolume.SetUp succeeded for volume "kube-dns-config"
Normal SuccessfulMountVolume 28m kubelet, MountVolume.SetUp succeeded for volume "kube-dns-token-h4q66"
Normal Pulling 28m kubelet, pulling image "k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.10"
Normal Pulled 28m kubelet, Successfully pulled image "k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.10"
Normal Started 28m kubelet, Started container
Normal Created 28m kubelet, Created container
Normal Pulling 28m kubelet, pulling image "k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.10"
Normal Pulling 28m kubelet, pulling image "k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.10"
Normal Pulled 28m kubelet, Successfully pulled image "k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.10"
Normal Created 28m kubelet, Created container
Normal Pulled 28m kubelet, Successfully pulled image "k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.10"
Normal Started 28m kubelet, Started container
Normal Created 25m (x2 over 28m) kubelet, Created container
Normal Started 25m (x2 over 28m) kubelet, Started container
Normal Killing 25m kubelet, Killing container with id docker://dnsmasq:Container failed liveness probe.. Container will be killed and recreated.
Normal Pulled 25m kubelet, Container image "k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.10" already present on machine
Warning Unhealthy 4m (x26 over 27m) kubelet, Liveness probe failed: HTTP probe failed with statuscode: 503
kube-dns sidecar容器日志：
kubectl logs kube-dns-75966d58fb-pqxz4 -n kube-system -c sidecar
I0809 16:31:26.768964 1 main.go:51] Version v1.14.8.3
I0809 16:31:26.769049 1 server.go:45] Starting server (options {DnsMasqPort:53 DnsMasqAddr:127.0.0.1 DnsMasqPollIntervalMs:5000 Probes:[{Label:kubedns Server:127.0.0.1:10053 Name:kubernetes.default.svc.cluster.local. Interval:5s Type:1} {Label:dnsmasq Server:127.0.0.1:53 Name:kubernetes.default.svc.cluster.local. Interval:5s Type:1}] PrometheusAddr:0.0.0.0 PrometheusPort:10054 PrometheusPath:/metrics PrometheusNamespace:kubedns})
I0809 16:31:26.769079 1 dnsprobe.go:75] Starting dnsProbe {Label:kubedns Server:127.0.0.1:10053 Name:kubernetes.default.svc.cluster.local. Interval:5s Type:1}
I0809 16:31:26.769117 1 dnsprobe.go:75] Starting dnsProbe {Label:dnsmasq Server:127.0.0.1:53 Name:kubernetes.default.svc.cluster.local. Interval:5s Type:1}
W0809 16:31:33.770594 1 server.go:64] Error getting metrics from dnsmasq: read udp 127.0.0.1:49305->127.0.0.1:53: i/o timeout
W0809 16:31:40.771166 1 server.go:64] Error getting metrics from dnsmasq: read udp 127.0.0.1:49655->127.0.0.1:53: i/o timeout
W0809 16:31:47.771773 1 server.go:64] Error getting metrics from dnsmasq: read udp 127.0.0.1:53322->127.0.0.1:53: i/o timeout
W0809 16:31:54.772386 1 server.go:64] Error getting metrics from dnsmasq: read udp 127.0.0.1:58999->127.0.0.1:53: i/o timeout
W0809 16:32:01.772972 1 server.go:64] Error getting metrics from dnsmasq: read udp 127.0.0.1:35034->127.0.0.1:53: i/o timeout
W0809 16:32:08.773540 1 server.go:64] Error getting metrics from dnsmasq: read udp 127.0.0.1:33250->127.0.0.1:53: i/o timeout
kube-dns dnsmasq容器日志：
kubectl logs kube-dns-75966d58fb-pqxz4 -n kube-system -c dnsmasq
I0809 16:29:51.596517 1 main.go:74] opts: {{/usr/sbin/dnsmasq [-k --cache-size=1000 --dns-forward-max=150 --no-negcache --log-facility=- --server=/cluster.local/127.0.0.1#10053 --server=/in-addr.arpa/127.0.0.1#10053 --server=/in6.arpa/127.0.0.1#10053] true} /etc/k8s/dns/dnsmasq-nanny 10000000000}
I0809 16:29:51.596679 1 nanny.go:94] Starting dnsmasq [-k --cache-size=1000 --dns-forward-max=150 --no-negcache --log-facility=- --server=/cluster.local/127.0.0.1#10053 --server=/in-addr.arpa/127.0.0.1#10053 --server=/in6.arpa/127.0.0.1#10053]
I0809 16:29:52.135179 1 nanny.go:119]
W0809 16:29:52.135211 1 nanny.go:120] Got EOF from stdout
I0809 16:29:52.135277 1 nanny.go:116] dnsmasq[20]: started, version 2.78 cachesize 1000
I0809 16:29:52.135293 1 nanny.go:116] dnsmasq[20]: compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP DHCPv6 no-Lua TFTP no-conntrack ipset auth no-DNSSEC loop-detect inotify
I0809 16:29:52.135303 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.1#10053 for domain in6.arpa
I0809 16:29:52.135314 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.1#10053 for domain in-addr.arpa
I0809 16:29:52.135323 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.1#10053 for domain cluster.local
I0809 16:29:52.135329 1 nanny.go:116] dnsmasq[20]: reading /etc/resolv.conf
I0809 16:29:52.135334 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.1#10053 for domain in6.arpa
I0809 16:29:52.135343 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.1#10053 for domain in-addr.arpa
I0809 16:29:52.135348 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.1#10053 for domain cluster.local
I0809 16:29:52.135353 1 nanny.go:116] dnsmasq[20]: using nameserver 127.0.0.53#53
I0809 16:29:52.135397 1 nanny.go:116] dnsmasq[20]: read /etc/hosts - 7 addresses
I0809 16:31:28.728897 1 nanny.go:116] dnsmasq[20]: Maximum number of concurrent DNS queries reached (max: 150)
I0809 16:31:38.746899 1 nanny.go:116] dnsmasq[20]: Maximum number of concurrent DNS queries reached (max: 150)
我已经删除了现有的Pod，但是新创建的模块在一段时间后出现了相同的错误。不确定为什么仅在Ubuntu 18上会发生这种情况。有什么想法解决此问题吗？
答案 0 :(得分：2)
Ubuntu 18使用systemd-resolved作为侦听127.0.0.53的DNS服务器。您可以看一下您的resolv.conf文件。当/etc/resolv.conf映射到CoreDNS时，它充当上游DNS服务器，但是循环检测插件失败。您可以看看CoreDNS troubleshooting page
在我的Ubuntu 18集群中，我禁用了systemd-resolved。
答案 1 :(得分：2)
就我而言，我发现在ubuntu18中，resolve.conf指向的是：/etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf
并且它有nameserver 127.0.0.53个条目。
同时在/ run / systemd / resolve下，您应该有另一个resolv.conf
/run/systemd/resolve$ ll
total 8
drwxr-xr-x 2 systemd-resolve systemd-resolve 80 Aug 12 13:24 ./
drwxr-xr-x 23 root root 520 Aug 12 11:54 ../
-rw-r--r-- 1 systemd-resolve systemd-resolve 607 Aug 12 13:24 resolv.conf
-rw-r--r-- 1 systemd-resolve systemd-resolve 735 Aug 12 13:24 stub-resolv.conf
在我的情况下，resolv.conf包含私有IP名称服务器172.27.0.2。 只需重新链接到所有群集计算机上的../run/systemd/resolve/resolv.conf并重新启动kube-dns pod。