K
Q

Question

KubeDNS error, server misbehaving

5/22/2018

I have a problem trying exec'ing into a container:

kubectl exec -it busybox-68654f944b-hj672 -- nslookup kubernetes
Error from server: error dialing backend: dial tcp: lookup worker2 on 127.0.0.53:53: server misbehaving

Or getting logs from a container:

kubectl -n kube-system logs kube-dns-598d7bf7d4-p99qr kubedns
Error from server: Get https://worker3:10250/containerLogs/kube-system/kube-dns-598d7bf7d4-p99qr/kubedns: dial tcp: lookup worker3 on 127.0.0.53:53: server misbehaving

I'm running out of ideas... I have followed mostly kubernetes-the-hard-way, but have installed it on DigitalOcean and using Flannel for pod networking (I'm also using digitalocean-cloud-manager that seems to be working well).

Also, it seems kube-proxy works, everything looks good in the logs, and the iptable config looks good (to me/a noob)

Networks:

10.244.0.0/16 Flannel / Pod network
10.32.0.0/24 kube-proxy(?) / Service cluster
kube3 206.x.x.211 / 10.133.55.62
kube1 206.x.x.80 / 10.133.52.77
kube2 206.x.x.213 / 10.133.55.73
worker1 167.x.x.148 / 10.133.56.88
worker3 206.x.x.121 / 10.133.55.220
worker2 206.x.x.113 / 10.133.56.89

So, my logs:

kube-dns:

E0522 12:22:32 reflector.go:201] k8s.io/dns/pkg/dns/dns.go:150: Failed to list *v1.Service: Get https://10.32.0.1:443/api/v1/services?resourceVersion=0: dial tcp 10.32.0.1:443: getsockopt: no route to host
E0522 12:22:32 reflector.go:201] k8s.io/dns/pkg/dns/dns.go:147: Failed to list *v1.Endpoints: Get https://10.32.0.1:443/api/v1/endpoints?resourceVersion=0: dial tcp 10.32.0.1:443: getsockopt: no route to host
I0522 12:22:32 dns.go:173] Waiting for services and endpoints to be initialized from apiserver...
I0522 12:22:33 dns.go:173] Waiting for services and endpoints to be initialized from apiserver...
I0522 12:22:33 dns.go:173] Waiting for services and endpoints to be initialized from apiserver...
F0522 12:22:34 dns.go:167] Timeout waiting for initialization

Kube-proxy:

I0522 12:36:37 flags.go:27] FLAG: --alsologtostderr="false"
I0522 12:36:37 flags.go:27] FLAG: --bind-address="0.0.0.0"
I0522 12:36:37 flags.go:27] FLAG: --cleanup="false"
I0522 12:36:37 flags.go:27] FLAG: --cleanup-iptables="false"
I0522 12:36:37 flags.go:27] FLAG: --cleanup-ipvs="true"
I0522 12:36:37 flags.go:27] FLAG: --cluster-cidr=""
I0522 12:36:37 flags.go:27] FLAG: --config="/var/lib/kube-proxy/kube-proxy-config.yaml"
I0522 12:36:37 flags.go:27] FLAG: --config-sync-period="15m0s"
I0522 12:36:37 flags.go:27] FLAG: --conntrack-max="0"
I0522 12:36:37 flags.go:27] FLAG: --conntrack-max-per-core="32768"
I0522 12:36:37 flags.go:27] FLAG: --conntrack-min="131072"
I0522 12:36:37 flags.go:27] FLAG: --conntrack-tcp-timeout-close-wait="1h0m0s"
I0522 12:36:37 flags.go:27] FLAG: --conntrack-tcp-timeout-established="24h0m0s"
I0522 12:36:37 flags.go:27] FLAG: --feature-gates=""
I0522 12:36:37 flags.go:27] FLAG: --healthz-bind-address="0.0.0.0:10256"
I0522 12:36:37 flags.go:27] FLAG: --healthz-port="10256"
I0522 12:36:37 flags.go:27] FLAG: --help="false"
I0522 12:36:37 flags.go:27] FLAG: --hostname-override=""
I0522 12:36:37 flags.go:27] FLAG: --iptables-masquerade-bit="14"
I0522 12:36:37 flags.go:27] FLAG: --iptables-min-sync-period="0s"
I0522 12:36:37 flags.go:27] FLAG: --iptables-sync-period="30s"
I0522 12:36:37 flags.go:27] FLAG: --ipvs-min-sync-period="0s"
I0522 12:36:37 flags.go:27] FLAG: --ipvs-scheduler=""
I0522 12:36:37 flags.go:27] FLAG: --ipvs-sync-period="30s"
I0522 12:36:37 flags.go:27] FLAG: --kube-api-burst="10"
I0522 12:36:37 flags.go:27] FLAG: --kube-api-content-type="application/vnd.kubernetes.protobuf"
I0522 12:36:37 flags.go:27] FLAG: --kube-api-qps="5"
I0522 12:36:37 flags.go:27] FLAG: --kubeconfig=""
I0522 12:36:37 flags.go:27] FLAG: --log-backtrace-at=":0"
I0522 12:36:37 flags.go:27] FLAG: --log-dir=""
I0522 12:36:37 flags.go:27] FLAG: --log-flush-frequency="5s"
I0522 12:36:37 flags.go:27] FLAG: --logtostderr="true"
I0522 12:36:37 flags.go:27] FLAG: --masquerade-all="false"
I0522 12:36:37 flags.go:27] FLAG: --master=""
I0522 12:36:37 flags.go:27] FLAG: --metrics-bind-address="127.0.0.1:10249"
I0522 12:36:37 flags.go:27] FLAG: --nodeport-addresses="[]"
I0522 12:36:37 flags.go:27] FLAG: --oom-score-adj="-999"
I0522 12:36:37 flags.go:27] FLAG: --profiling="false"
I0522 12:36:37 flags.go:27] FLAG: --proxy-mode=""
I0522 12:36:37 flags.go:27] FLAG: --proxy-port-range=""
I0522 12:36:37 flags.go:27] FLAG: --resource-container="/kube-proxy"
I0522 12:36:37 flags.go:27] FLAG: --stderrthreshold="2"
I0522 12:36:37 flags.go:27] FLAG: --udp-timeout="250ms"
I0522 12:36:37 flags.go:27] FLAG: --v="4"
I0522 12:36:37 flags.go:27] FLAG: --version="false"
I0522 12:36:37 flags.go:27] FLAG: --vmodule=""
I0522 12:36:37 flags.go:27] FLAG: --write-config-to=""
I0522 12:36:37 feature_gate.go:226] feature gates: &{{} map[]}
I0522 12:36:37 iptables.go:589] couldn't get iptables-restore version; assuming it doesn't support --wait
I0522 12:36:37 server_others.go:140] Using iptables Proxier.
I0522 12:36:37 proxier.go:346] minSyncPeriod: 0s, syncPeriod: 30s, burstSyncs: 2
I0522 12:36:37 server_others.go:174] Tearing down inactive rules.
I0522 12:36:37 server.go:444] Version: v1.10.2
I0522 12:36:37 oom_linux.go:65] attempting to set "/proc/self/oom_score_adj" to "-999"
I0522 12:36:37 server.go:470] Running in resource-only container "/kube-proxy"
I0522 12:36:37 healthcheck.go:309] Starting goroutine for healthz on 0.0.0.0:10256
I0522 12:36:37 server.go:591] getConntrackMax: using conntrack-min
I0522 12:36:37 conntrack.go:98] Set sysctl 'net/netfilter/nf_conntrack_max' to 131072
I0522 12:36:37 conntrack.go:52] Setting nf_conntrack_max to 131072
I0522 12:36:37 conntrack.go:98] Set sysctl 'net/netfilter/nf_conntrack_tcp_timeout_established' to 86400
I0522 12:36:37 conntrack.go:98] Set sysctl 'net/netfilter/nf_conntrack_tcp_timeout_close_wait' to 3600
I0522 12:36:37 bounded_frequency_runner.go:170] sync-runner Loop running
I0522 12:36:37 config.go:102] Starting endpoints config controller
I0522 12:36:37 config.go:202] Starting service config controller
I0522 12:36:37 controller_utils.go:1019] Waiting for caches to sync for service config controller
I0522 12:36:37 reflector.go:202] Starting reflector *core.Endpoints (15m0s) from k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86
I0522 12:36:37 reflector.go:240] Listing and watching *core.Endpoints from k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86
I0522 12:36:37 reflector.go:202] Starting reflector *core.Service (15m0s) from k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86
I0522 12:36:37 reflector.go:240] Listing and watching *core.Service from k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86
I0522 12:36:37 config.go:124] Calling handler.OnEndpointsAdd
I0522 12:36:37 endpoints.go:234] Setting endpoints for "kube-system/kubernetes-dashboard:" to [10.244.0.2:8443]
I0522 12:36:37 config.go:124] Calling handler.OnEndpointsAdd
I0522 12:36:37 endpoints.go:234] Setting endpoints for "default/hostnames:" to [10.244.0.3:9376 10.244.0.4:9376 10.244.0.4:9376]
I0522 12:36:37 config.go:124] Calling handler.OnEndpointsAdd
I0522 12:36:37 endpoints.go:234] Setting endpoints for "default/kubernetes:https" to [10.133.52.77:6443 10.133.55.62:6443 10.133.55.73:6443]
I0522 12:36:37 config.go:124] Calling handler.OnEndpointsAdd
I0522 12:36:37 config.go:124] Calling handler.OnEndpointsAdd
I0522 12:36:37 endpoints.go:234] Setting endpoints for "kube-system/kube-dns:dns" to []
I0522 12:36:37 endpoints.go:234] Setting endpoints for "kube-system/kube-dns:dns-tcp" to []
I0522 12:36:37 config.go:124] Calling handler.OnEndpointsAdd
I0522 12:36:37 config.go:224] Calling handler.OnServiceAdd
I0522 12:36:37 config.go:224] Calling handler.OnServiceAdd
I0522 12:36:37 config.go:224] Calling handler.OnServiceAdd
I0522 12:36:37 config.go:224] Calling handler.OnServiceAdd
I0522 12:36:37 controller_utils.go:1019] Waiting for caches to sync for endpoints config controller
I0522 12:36:37 shared_informer.go:123] caches populated
I0522 12:36:37 controller_utils.go:1026] Caches are synced for service config controller
I0522 12:36:37 config.go:210] Calling handler.OnServiceSynced()
I0522 12:36:37 proxier.go:623] Not syncing iptables until Services and Endpoints have been received from master
I0522 12:36:37 proxier.go:619] syncProxyRules took 38.306µs
I0522 12:36:37 shared_informer.go:123] caches populated
I0522 12:36:37 controller_utils.go:1026] Caches are synced for endpoints config controller
I0522 12:36:37 config.go:110] Calling handler.OnEndpointsSynced()
I0522 12:36:37 service.go:310] Adding new service port "default/kubernetes:https" at 10.32.0.1:443/TCP
I0522 12:36:37 service.go:310] Adding new service port "kube-system/kube-dns:dns" at 10.32.0.10:53/UDP
I0522 12:36:37 service.go:310] Adding new service port "kube-system/kube-dns:dns-tcp" at 10.32.0.10:53/TCP
I0522 12:36:37 service.go:310] Adding new service port "kube-system/kubernetes-dashboard:" at 10.32.0.175:443/TCP
I0522 12:36:37 service.go:310] Adding new service port "default/hostnames:" at 10.32.0.16:80/TCP
I0522 12:36:37 proxier.go:642] Syncing iptables rules
I0522 12:36:37 iptables.go:321] running iptables-save [-t filter]
I0522 12:36:37 iptables.go:321] running iptables-save [-t nat]
I0522 12:36:37 iptables.go:381] running iptables-restore [--noflush --counters]
I0522 12:36:37 healthcheck.go:235] Not saving endpoints for unknown healthcheck "default/hostnames"
I0522 12:36:37 proxier.go:619] syncProxyRules took 62.713913ms
I0522 12:36:38 config.go:141] Calling handler.OnEndpointsUpdate
I0522 12:36:38 config.go:141] Calling handler.OnEndpointsUpdate
I0522 12:36:40 config.go:141] Calling handler.OnEndpointsUpdate
I0522 12:36:40 config.go:141] Calling handler.OnEndpointsUpdate

iptables -L -t nat

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         
KUBE-SERVICES  all  --  anywhere             anywhere             /* kubernetes service portals */
DOCKER     all  --  anywhere             anywhere             ADDRTYPE match dst-type LOCAL

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
KUBE-SERVICES  all  --  anywhere             anywhere             /* kubernetes service portals */
DOCKER     all  --  anywhere            !localhost/8          ADDRTYPE match dst-type LOCAL

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination         
KUBE-POSTROUTING  all  --  anywhere             anywhere             /* kubernetes postrouting rules */
MASQUERADE  all  --  172.17.0.0/16        anywhere            
RETURN     all  --  10.244.0.0/16        10.244.0.0/16       
MASQUERADE  all  --  10.244.0.0/16       !base-address.mcast.net/4 
RETURN     all  -- !10.244.0.0/16        worker3/24          
MASQUERADE  all  -- !10.244.0.0/16        10.244.0.0/16       
CNI-9f557b5f70a3ef9b57012dc9  all  --  10.244.0.0/16        anywhere             /* name: "bridge" id: "0d9b7e94498291d71ff1952655da822ab1a1f7c4e080d119ff0ca84a506f05f5" */
CNI-3f77e9111033967f6fe3038c  all  --  10.244.0.0/16        anywhere             /* name: "bridge" id: "3b535dda0868b2d75046fc76de3279de2874652b6731a87815908ecf40dd1924" */

Chain CNI-3f77e9111033967f6fe3038c (1 references)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             10.244.0.0/16        /* name: "bridge" id: "3b535dda0868b2d75046fc76de3279de2874652b6731a87815908ecf40dd1924" */
MASQUERADE  all  --  anywhere            !base-address.mcast.net/4  /* name: "bridge" id: "3b535dda0868b2d75046fc76de3279de2874652b6731a87815908ecf40dd1924" */

Chain CNI-9f557b5f70a3ef9b57012dc9 (1 references)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             10.244.0.0/16        /* name: "bridge" id: "0d9b7e94498291d71ff1952655da822ab1a1f7c4e080d119ff0ca84a506f05f5" */
MASQUERADE  all  --  anywhere            !base-address.mcast.net/4  /* name: "bridge" id: "0d9b7e94498291d71ff1952655da822ab1a1f7c4e080d119ff0ca84a506f05f5" */

Chain DOCKER (2 references)
target     prot opt source               destination         
RETURN     all  --  anywhere             anywhere            

Chain KUBE-MARK-DROP (0 references)
target     prot opt source               destination         
MARK       all  --  anywhere             anywhere             MARK or 0x8000

Chain KUBE-MARK-MASQ (10 references)
target     prot opt source               destination         
MARK       all  --  anywhere             anywhere             MARK or 0x4000

Chain KUBE-NODEPORTS (1 references)
target     prot opt source               destination         

Chain KUBE-POSTROUTING (1 references)
target     prot opt source               destination         
MASQUERADE  all  --  anywhere             anywhere             /* kubernetes service traffic requiring SNAT */ mark match 0x4000/0x4000

Chain KUBE-SEP-372W2QPHULAJK7KN (2 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  all  --  10.133.52.77         anywhere             /* default/kubernetes:https */
DNAT       tcp  --  anywhere             anywhere             /* default/kubernetes:https */ recent: SET name: KUBE-SEP-372W2QPHULAJK7KN side: source mask: 255.255.255.255 tcp to:10.133.52.77:6443

Chain KUBE-SEP-F5C5FPCVD73UOO2K (2 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  all  --  10.133.55.73         anywhere             /* default/kubernetes:https */
DNAT       tcp  --  anywhere             anywhere             /* default/kubernetes:https */ recent: SET name: KUBE-SEP-F5C5FPCVD73UOO2K side: source mask: 255.255.255.255 tcp to:10.133.55.73:6443

Chain KUBE-SEP-LFOBDGSNKNVH4XYX (2 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  all  --  10.133.55.62         anywhere             /* default/kubernetes:https */
DNAT       tcp  --  anywhere             anywhere             /* default/kubernetes:https */ recent: SET name: KUBE-SEP-LFOBDGSNKNVH4XYX side: source mask: 255.255.255.255 tcp to:10.133.55.62:6443

Chain KUBE-SEP-NBPTKIZVPOJSUO47 (2 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  all  --  10.244.0.4           anywhere             /* default/hostnames: */
DNAT       tcp  --  anywhere             anywhere             /* default/hostnames: */ tcp to:10.244.0.4:9376
KUBE-MARK-MASQ  all  --  10.244.0.4           anywhere             /* default/hostnames: */
DNAT       tcp  --  anywhere             anywhere             /* default/hostnames: */ tcp to:10.244.0.4:9376

Chain KUBE-SEP-OT5RYZRAA2AMYTNV (1 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  all  --  10.244.0.2           anywhere             /* kube-system/kubernetes-dashboard: */
DNAT       tcp  --  anywhere             anywhere             /* kube-system/kubernetes-dashboard: */ tcp to:10.244.0.2:8443

Chain KUBE-SEP-XDZOTYYMKVEAAZHH (1 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  all  --  10.244.0.3           anywhere             /* default/hostnames: */
DNAT       tcp  --  anywhere             anywhere             /* default/hostnames: */ tcp to:10.244.0.3:9376

Chain KUBE-SERVICES (2 references)
target     prot opt source               destination         
KUBE-MARK-MASQ  tcp  -- !10.244.0.0/16        10.32.0.1            /* default/kubernetes:https cluster IP */ tcp dpt:https
KUBE-SVC-NPX46M4PTMTKRN6Y  tcp  --  anywhere             10.32.0.1            /* default/kubernetes:https cluster IP */ tcp dpt:https
KUBE-MARK-MASQ  tcp  -- !10.244.0.0/16        10.32.0.175          /* kube-system/kubernetes-dashboard: cluster IP */ tcp dpt:https
KUBE-SVC-XGLOHA7QRQ3V22RZ  tcp  --  anywhere             10.32.0.175          /* kube-system/kubernetes-dashboard: cluster IP */ tcp dpt:https
KUBE-MARK-MASQ  tcp  -- !10.244.0.0/16        10.32.0.16           /* default/hostnames: cluster IP */ tcp dpt:http
KUBE-SVC-NWV5X2332I4OT4T3  tcp  --  anywhere             10.32.0.16           /* default/hostnames: cluster IP */ tcp dpt:http
KUBE-NODEPORTS  all  --  anywhere             anywhere             /* kubernetes service nodeports; NOTE: this must be the last rule in this chain */ ADDRTYPE match dst-type LOCAL

Chain KUBE-SVC-NPX46M4PTMTKRN6Y (1 references)
target     prot opt source               destination         
KUBE-SEP-372W2QPHULAJK7KN  all  --  anywhere             anywhere             /* default/kubernetes:https */ recent: CHECK seconds: 10800 reap name: KUBE-SEP-372W2QPHULAJK7KN side: source mask: 255.255.255.255
KUBE-SEP-LFOBDGSNKNVH4XYX  all  --  anywhere             anywhere             /* default/kubernetes:https */ recent: CHECK seconds: 10800 reap name: KUBE-SEP-LFOBDGSNKNVH4XYX side: source mask: 255.255.255.255
KUBE-SEP-F5C5FPCVD73UOO2K  all  --  anywhere             anywhere             /* default/kubernetes:https */ recent: CHECK seconds: 10800 reap name: KUBE-SEP-F5C5FPCVD73UOO2K side: source mask: 255.255.255.255
KUBE-SEP-372W2QPHULAJK7KN  all  --  anywhere             anywhere             /* default/kubernetes:https */ statistic mode random probability 0.33332999982
KUBE-SEP-LFOBDGSNKNVH4XYX  all  --  anywhere             anywhere             /* default/kubernetes:https */ statistic mode random probability 0.50000000000
KUBE-SEP-F5C5FPCVD73UOO2K  all  --  anywhere             anywhere             /* default/kubernetes:https */

Chain KUBE-SVC-NWV5X2332I4OT4T3 (1 references)
target     prot opt source               destination         
KUBE-SEP-XDZOTYYMKVEAAZHH  all  --  anywhere             anywhere             /* default/hostnames: */ statistic mode random probability 0.33332999982
KUBE-SEP-NBPTKIZVPOJSUO47  all  --  anywhere             anywhere             /* default/hostnames: */ statistic mode random probability 0.50000000000
KUBE-SEP-NBPTKIZVPOJSUO47  all  --  anywhere             anywhere             /* default/hostnames: */

Chain KUBE-SVC-XGLOHA7QRQ3V22RZ (1 references)
target     prot opt source               destination         
KUBE-SEP-OT5RYZRAA2AMYTNV  all  --  anywhere             anywhere             /* kube-system/kubernetes-dashboard: */

kubelet

W12:43:36 prober.go:103] No ref for container "containerd://6405ae121704b15554e019beb622fbcf991e0d3c75b20eab606e147dc1e6966f" (kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns)
I12:43:36 prober.go:111] Readiness probe for "kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns" failed (failure): Get http://10.244.0.2:8081/readiness: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W12:43:46 prober.go:103] No ref for container "containerd://6405ae121704b15554e019beb622fbcf991e0d3c75b20eab606e147dc1e6966f" (kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns)
I12:43:46 prober.go:111] Readiness probe for "kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns" failed (failure): Get http://10.244.0.2:8081/readiness: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W12:43:56 prober.go:103] No ref for container "containerd://6405ae121704b15554e019beb622fbcf991e0d3c75b20eab606e147dc1e6966f" (kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns)
I12:43:56 prober.go:111] Readiness probe for "kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns" failed (failure): Get http://10.244.0.2:8081/readiness: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W12:44:06 prober.go:103] No ref for container "containerd://6405ae121704b15554e019beb622fbcf991e0d3c75b20eab606e147dc1e6966f" (kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns)
I12:44:06 prober.go:111] Readiness probe for "kube-dns-598d7bf7d4-p99qr_kube-system(46cf8d8f-5d11-11e8-b2be-eefd92698760):kubedns" failed (failure): Get http://10.244.0.2:8081/readiness: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)

Config:

Worker:

kubelet:

systemd service:

/usr/local/bin/kubelet \
  --config=/var/lib/kubelet/kubelet-config.yaml \
  --container-runtime=remote \
  --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock \
  --image-pull-progress-deadline=2m \
  --kubeconfig=/var/lib/kubelet/kubeconfig \
  --network-plugin=cni \
  --register-node=true \
  --v=2 \
  --cloud-provider=external \
  --allow-privileged=true

kubelet-config.yaml:

kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
authentication:
  anonymous:
    enabled: false
  webhook:
    enabled: true
  x509:
    clientCAFile: "/var/lib/kubernetes/ca.pem"
authorization:
  mode: Webhook
clusterDomain: "cluster.local"
clusterDNS:
  - "10.32.0.10"
podCIDR: "10.244.0.0/16"
runtimeRequestTimeout: "15m"
tlsCertFile: "/var/lib/kubelet/worker3.pem"
tlsPrivateKeyFile: "/var/lib/kubelet/worker3-key.pem"

kube-proxy:

systemd service:

ExecStart=/usr/local/bin/kube-proxy \ --config=/var/lib/kube-proxy/kube-proxy-config.yaml -v 4

kube-proxy-config.yaml:

kind: KubeProxyConfiguration
apiVersion: kubeproxy.config.k8s.io/v1alpha1
clientConnection:
  kubeconfig: "/var/lib/kube-proxy/kubeconfig"
mode: "iptables"
clusterCIDR: "10.244.0.0/16"

kubeconfig:

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: ASLDJL...ALKJDS=
    server: https://206.x.x.7:6443
  name: kubernetes-the-hard-way
contexts:
- context:
    cluster: kubernetes-the-hard-way
    user: system:kube-proxy
  name: default
current-context: default
kind: Config
preferences: {}
users:
- name: system:kube-proxy
  user:
    client-certificate-data: ASDLJAL ... ALDJS
    client-key-data: LS0tLS1CRUdJ...ASDJ

Controller:

kube-apiserver:

ExecStart=/usr/local/bin/kube-apiserver \
  --advertise-address=10.133.55.62 \
  --allow-privileged=true \
  --apiserver-count=3 \
  --audit-log-maxage=30 \
  --audit-log-maxbackup=3 \
  --audit-log-maxsize=100 \
  --audit-log-path=/var/log/audit.log \
  --authorization-mode=Node,RBAC \
  --bind-address=0.0.0.0 \
  --client-ca-file=/var/lib/kubernetes/ca.pem \
  --enable-admission-plugins=Initializers,NamespaceLifecycle,NodeRestriction,LimitRanger,ServiceAccount,DefaultStorageClass,ResourceQuota \
  --enable-swagger-ui=true \
  --etcd-cafile=/var/lib/kubernetes/ca.pem \
  --etcd-certfile=/var/lib/kubernetes/kubernetes.pem \
  --etcd-keyfile=/var/lib/kubernetes/kubernetes-key.pem \
  --etcd-servers=https://10.133.55.73:2379,https://10.133.52.77:2379,https://10.133.55.62:2379 \
  --event-ttl=1h \
  --experimental-encryption-provider-config=/var/lib/kubernetes/encryption-config.yaml \
  --kubelet-certificate-authority=/var/lib/kubernetes/ca.pem \
  --kubelet-client-certificate=/var/lib/kubernetes/kubernetes.pem \
  --kubelet-client-key=/var/lib/kubernetes/kubernetes-key.pem \
  --kubelet-https=true \
  --runtime-config=api/all \
  --service-account-key-file=/var/lib/kubernetes/service-account.pem \
  --service-cluster-ip-range=10.32.0.0/24 \
  --service-node-port-range=30000-32767 \
  --tls-cert-file=/var/lib/kubernetes/kubernetes.pem \
  --tls-private-key-file=/var/lib/kubernetes/kubernetes-key.pem \
  --v=2

kube-controller-manager

ExecStart=/usr/local/bin/kube-controller-manager \
  --address=0.0.0.0 \
  --cluster-cidr=10.244.0.0/16 \
  --allocate-node-cidrs=true \
  --cluster-name=kubernetes \
  --cluster-signing-cert-file=/var/lib/kubernetes/ca.pem \
  --cluster-signing-key-file=/var/lib/kubernetes/ca-key.pem \
  --kubeconfig=/var/lib/kubernetes/kube-controller-manager.kubeconfig \
  --leader-elect=true \
  --root-ca-file=/var/lib/kubernetes/ca.pem \
  --service-account-private-key-file=/var/lib/kubernetes/service-account-key.pem \
  --service-cluster-ip-range=10.32.0.0/24 \
  --use-service-account-credentials=true \
  --v=2

Flannel config/Log:

https://pastebin.com/hah0uSFX (since the post is too long!)

Edit:

route:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    0      0        0 eth0
10.18.0.0       0.0.0.0         255.255.0.0     U     0      0        0 eth0
10.133.0.0      0.0.0.0         255.255.0.0     U     0      0        0 eth1
10.244.0.0      10.244.0.0      255.255.255.0   UG    0      0        0 flannel.1
10.244.0.0      0.0.0.0         255.255.0.0     U     0      0        0 cnio0
10.244.1.0      10.244.1.0      255.255.255.0   UG    0      0        0 flannel.1
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0
206.189.96.0    0.0.0.0         255.255.240.0   U     0      0        0 eth0

ip route get 10.32.0.1: 10.32.0.1 via 206.189.96.1 dev eth0 src 206.189.96.121 uid 0

curl -k https://10.32.0.1:443/version 
{
  "major": "1",
  "minor": "10",
  "gitVersion": "v1.10.2",
  "gitCommit": "81753b10df112992bf51bbc2c2f85208aad78335",
  "gitTreeState": "clean",
  "buildDate": "2018-04-27T09:10:24Z",
  "goVersion": "go1.9.3",
  "compiler": "gc",
  "platform": "linux/amd64"
}

A reboot brought up all workers and pods, including kube-dns, so they are not crashing anymore, but when trying to do exec or run, I still have some issues:

kubectl run test --image=ubuntu -it --rm bash
If you don't see a command prompt, try pressing enter.
Error attaching, falling back to logs: error dialing backend: dial tcp: lookup worker3 on 127.0.0.53:53: server misbehaving
Error from server: Get https://worker3:10250/containerLogs/default/test-6954947c4f-6gkdl/test: dial tcp: lookup worker3 on 127.0.0.53:53: server misbehavin

-- Richard87

dns

docker

flannel

kube-dns

kubernetes

1 Answer

5/23/2018

I have a problem trying exec'ing into a container

As you see, Kubernetes is trying to connect to your nodes use the names like worker1, which cannot be resolved in your network.

You have 2 ways to fix it:

Use real FQDN for all your nodes which can be resolved. Usually, VMs in clouds have resolvable DNS names, but it looks like in DO they are not. So, you need to create domain names manually and point them to your servers. Try to check DO DNS service. I recommend you that way, it is always good when you have your own DNS names for your infrastructure.
Make your names like worker1 resolvable for Kubernetes components, maybe some custom DNS server or records in /etc/hosts.

UPD:

From @Richard87, for future reference: the third way is to use option --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname.

-- Anton Kostenko

Source: StackOverflow

KQ