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私のKubernetesホストのDockerとは異なり、nslookup google.comはKubernetesポッドで失敗します。さらに重要なことはnslookup kubernetesです。なぜどんなアイデア？以下の関連情報。Kubernetes DNSはポッドで失敗しますが、Dockerコンテナで動作します
kubectl version
Client Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.5", GitCommit:"17d7182a7ccbb167074be7a87f0a68bd00d58d97", GitTreeState:"clean", BuildDate:"2017-08-31T09:14:02Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.9", GitCommit:"19fe91923d584c30bd6db5c5a21e9f0d5f742de8", GitTreeState:"clean", BuildDate:"2017-10-19T16:55:06Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/amd64"}
[[email protected] ~]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
[[email protected] ~]# cat /etc/resolv.conf
search company.com
nameserver 192.168.1.254
# flannel
[[email protected] ~]# kubectl describe --namespace=kube-system cm kube-flannel-cfg
Name: kube-flannel-cfg
Namespace: kube-system
Labels: app=flannel
tier=node
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"v1","data":{"cni-conf.json":"{\n \"name\": \"cbr0\",\n \"type\": \"flannel\",\n \"delegate\": {\n \"isDefaultGateway\": true\n }\...
Data
====
cni-conf.json:
----
{
"name": "cbr0",
"type": "flannel",
"delegate": {
"isDefaultGateway": true
}
}
net-conf.json:
----
{
"Network": "10.244.0.0/16",
"Backend": {
"Type": "vxlan"
}
}
Events: <none>
"
[[email protected] ~]# ping google.com
PING google.com (216.58.192.206) 56(84) bytes of data.
[[email protected] ~]# docker run -ti busybox /bin/sh
/# nslookup google.com
Server: 192.168.1.254
Address 1: 192.168.1.254 server.local
Name: google.com
Address 1: 2607:f8b0:4009:80e::200e ord30s25-in-x0e.1e100.net
Address 2: 216.58.192.206 ord30s25-in-f206.1e100.net
[[email protected] ~]# kubectl exec -ti busybox -- /bin/sh
/# nslookup google.com
Server: 10.96.0.10
Address 1: 10.96.0.10
nslookup: can't resolve 'google.com'
/# nslookup kubernetes
Server: 10.96.0.10
Address 1: 10.96.0.10
nslookup: can't resolve 'kubernetes'
/# cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local mycompany.com
options ndots:5
/# ip route
default via 10.244.3.1 dev eth0
10.244.0.0/16 via 10.244.3.1 dev eth0
10.244.3.0/24 dev eth0 proto kernel scope link src 10.244.3.4
[[email protected]]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE
kube-dns-2425271678-nt31m 3/3 Running 3 2h
[[email protected] ]# kubectl logs --namespace=kube-system $(kubectl get pods --namespace=kube-system -l k8s-app=kube-dns -o name) -c kubedns
I1022 21:06:23.810037 6 dns.go:48] version: 1.14.3-4-gee838f6
I1022 21:06:23.812271 6 server.go:70] Using configuration read from directory: /kube-dns-config with period 10s
I1022 21:06:23.812306 6 server.go:113] FLAG: --alsologtostderr="false"
I1022 21:06:23.812313 6 server.go:113] FLAG: --config-dir="/kube-dns-config"
I1022 21:06:23.812317 6 server.go:113] FLAG: --config-map=""
I1022 21:06:23.812320 6 server.go:113] FLAG: --config-map-namespace="kube-system"
I1022 21:06:23.812323 6 server.go:113] FLAG: --config-period="10s"
I1022 21:06:23.812327 6 server.go:113] FLAG: --dns-bind-address="0.0.0.0"
I1022 21:06:23.812329 6 server.go:113] FLAG: --dns-port="10053"
I1022 21:06:23.812334 6 server.go:113] FLAG: --domain="cluster.local."
I1022 21:06:23.812338 6 server.go:113] FLAG: --federations=""
I1022 21:06:23.812342 6 server.go:113] FLAG: --healthz-port="8081"
I1022 21:06:23.812344 6 server.go:113] FLAG: --initial-sync-timeout="1m0s"
I1022 21:06:23.812347 6 server.go:113] FLAG: --kube-master-url=""
I1022 21:06:23.812371 6 server.go:113] FLAG: --kubecfg-file=""
I1022 21:06:23.812374 6 server.go:113] FLAG: --log-backtrace-at=":0"
I1022 21:06:23.812379 6 server.go:113] FLAG: --log-dir=""
I1022 21:06:23.812382 6 server.go:113] FLAG: --log-flush-frequency="5s"
I1022 21:06:23.812385 6 server.go:113] FLAG: --logtostderr="true"
I1022 21:06:23.812388 6 server.go:113] FLAG: --nameservers=""
I1022 21:06:23.812390 6 server.go:113] FLAG: --stderrthreshold="2"
I1022 21:06:23.812393 6 server.go:113] FLAG: --v="2"
I1022 21:06:23.812396 6 server.go:113] FLAG: --version="false"
I1022 21:06:23.812401 6 server.go:113] FLAG: --vmodule=""
I1022 21:06:23.812452 6 server.go:176] Starting SkyDNS server (0.0.0.0:10053)
I1022 21:06:23.812692 6 server.go:198] Skydns metrics enabled (/metrics:10055)
I1022 21:06:23.812701 6 dns.go:147] Starting endpointsController
I1022 21:06:23.812705 6 dns.go:150] Starting serviceController
I1022 21:06:23.812915 6 logs.go:41] skydns: ready for queries on cluster.local. for tcp://0.0.0.0:10053 [rcache 0]
I1022 21:06:23.812922 6 logs.go:41] skydns: ready for queries on cluster.local. for udp://0.0.0.0:10053 [rcache 0]
I1022 21:06:24.312871 6 dns.go:171] Initialized services and endpoints from apiserver
I1022 21:06:24.312904 6 server.go:129] Setting up Healthz Handler (/readiness)
I1022 21:06:24.312911 6 server.go:134] Setting up cache handler (/cache)
I1022 21:06:24.312916 6 server.go:120] Status HTTP port 8081
[[email protected] ]# kubectl logs --namespace=kube-system $(kubectl get pods --namespace=kube-system -l k8s-app=kube-dns -o name) -c dnsmasq
I1022 21:06:24.134376 18 main.go:76] opts: {{/usr/sbin/dnsmasq [-k --cache-size=1000 --log-facility=- --server=/cluster.local/127.0.0.1#10053 --server=/in-addr.arpa/127.0.0.1#10053 --server=/ip6.arpa/127.0.0.1#10053] true} /etc/k8s/dns/dnsmasq-nanny 10000000000}
I1022 21:06:24.134457 18 nanny.go:86] Starting dnsmasq [-k --cache-size=1000 --log-facility=- --server=/cluster.local/127.0.0.1#10053 --server=/in-addr.arpa/127.0.0.1#10053 --server=/ip6.arpa/127.0.0.1#10053]
I1022 21:06:24.155185 18 nanny.go:111]
W1022 21:06:24.155200 18 nanny.go:112] Got EOF from stdout
I1022 21:06:24.155215 18 nanny.go:108] dnsmasq[30]: started, version 2.76 cachesize 1000
I1022 21:06:24.155220 18 nanny.go:108] dnsmasq[30]: 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
I1022 21:06:24.155225 18 nanny.go:108] dnsmasq[30]: using nameserver 127.0.0.1#10053 for domain ip6.arpa
I1022 21:06:24.155228 18 nanny.go:108] dnsmasq[30]: using nameserver 127.0.0.1#10053 for domain in-addr.arpa
I1022 21:06:24.155231 18 nanny.go:108] dnsmasq[30]: using nameserver 127.0.0.1#10053 for domain cluster.local
I1022 21:06:24.155235 18 nanny.go:108] dnsmasq[30]: reading /etc/resolv.conf
I1022 21:06:24.155237 18 nanny.go:108] dnsmasq[30]: using nameserver 127.0.0.1#10053 for domain ip6.arpa
I1022 21:06:24.155240 18 nanny.go:108] dnsmasq[30]: using nameserver 127.0.0.1#10053 for domain in-addr.arpa
I1022 21:06:24.155242 18 nanny.go:108] dnsmasq[30]: using nameserver 127.0.0.1#10053 for domain cluster.local
I1022 21:06:24.155246 18 nanny.go:108] dnsmasq[30]: using nameserver 192.168.1.254#53
I1022 21:06:24.155303 18 nanny.go:108] dnsmasq[30]: read /etc/hosts - 7 addresses
[[email protected] ]# kubectl logs --namespace=kube-system $(kubectl get pods --namespace=kube-system -l k8s-app=kube-dns -o name) -c sidecar
ERROR: logging before flag.Parse: I1022 21:06:24.407699 31 main.go:48] Version v1.14.3-4-gee838f6
ERROR: logging before flag.Parse: I1022 21:06:24.407779 31 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})
ERROR: logging before flag.Parse: I1022 21:06:24.407824 31 dnsprobe.go:75] Starting dnsProbe {Label:kubedns Server:127.0.0.1:10053 Name:kubernetes.default.svc.cluster.local. Interval:5s Type:1}
ERROR: logging before flag.Parse: I1022 21:06:24.408243 31 dnsprobe.go:75] Starting dnsProbe {Label:dnsmasq Server:127.0.0.1:53 Name:kubernetes.default.svc.cluster.local. Interval:5s Type:1}
[[email protected] ]# kubectl get svc --namespace=kube-system
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns 10.96.0.10 <none> 53/UDP,53/TCP 2h
[[email protected] ]# kubectl get ep kube-dns --namespace=kube-system
NAME ENDPOINTS AGE
kube-dns 10.244.0.3:53,10.244.0.3:53 2h