Fresh Kubernetes (1.10.0) cluster stood up using kubeadm (1.10.0) install on RHEL7 bare metal VMs
Linux 3.10.0-693.11.6.el7.x86_64 #1 SMP Thu Dec 28 14:23:39 EST 2017 x86_64 x86_64 x86_64 GNU/Linux
kubeadm.x86_64 1.10.0-0 installed
kubectl.x86_64 1.10.0-0 installed
kubelet.x86_64 1.10.0-0 installed
kubernetes-cni.x86_64 0.6.0-0 installed
and 1.12 docker
docker-engine.x86_64 1.12.6-1.el7.centos installed
docker-engine-selinux.noarch 1.12.6-1.el7.centos installed
With Flannel v0.9.1 pod network installed
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.9.1/Documentation/kube-flannel.yml
kubeadm init comand I ran is
kubeadm init --pod-network-cidr=10.244.0.0/16 --kubernetes-version stable-1.10
which completes successfully and kubeadm join on worker node also successful. I can deploy busybox pod on the master and nslookups are successful, but as soon as I deploy anything to the worker node I get failed API calls from the worker node on the master:
E0331 03:28:44.368253 1 reflector.go:205] k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86: Failed to list *core.Service: Get https://172.30.0.85:6443/api/v1/services?limit=500&resourceVersion=0: dial tcp 172.30.0.85:6443: getsockopt: connection refused
E0331 03:28:44.368987 1 reflector.go:205] k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86: Failed to list *core.Endpoints: Get https://172.30.0.85:6443/api/v1/endpoints?limit=500&resourceVersion=0: dial tcp 172.30.0.85:6443: getsockopt: connection refused
E0331 03:28:44.735886 1 event.go:209] Unable to write event: 'Post https://172.30.0.85:6443/api/v1/namespaces/default/events: dial tcp 172.30.0.85:6443: getsockopt: connection refused' (may retry after sleeping)
E0331 03:28:51.980131 1 reflector.go:205] k8s.io/kubernetes/pkg/client/informers/informers_generated/internalversion/factory.go:86: Failed to list *core.Endpoints: endpoints is forbidden: User "system:serviceaccount:kube-system:kube-proxy" cannot list endpoints at the cluster scope
I0331 03:28:52.048995 1 controller_utils.go:1026] Caches are synced for service config controller
I0331 03:28:53.049005 1 controller_utils.go:1026] Caches are synced for endpoints config controller
and nslookup times out
kubectl exec -it busybox -- nslookup kubernetes
Server: 10.96.0.10
Address 1: 10.96.0.10
nslookup: can't resolve 'kubernetes'
command terminated with exit code 1
I have looked at many similar post on stackoverflow and github and all seem to be resolved with setting iptables -A FORWARD -j ACCEPT but not this time. I have also included the iptables from the worker node
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 !loopback/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 box2.ara.ac.nz/24
MASQUERADE all -- !10.244.0.0/16 10.244.0.0/16
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 (6 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-HZC4RESJCS322LXV (1 references)
target prot opt source destination
KUBE-MARK-MASQ all -- 10.244.0.18 anywhere /* kube-system/kube-dns:dns-tcp */
DNAT tcp -- anywhere anywhere /* kube-system/kube-dns:dns-tcp */ tcp to:10.244.0.18:53
Chain KUBE-SEP-JNNVSHBUREKVBFWD (1 references)
target prot opt source destination
KUBE-MARK-MASQ all -- 10.244.0.18 anywhere /* kube-system/kube-dns:dns */
DNAT udp -- anywhere anywhere /* kube-system/kube-dns:dns */ udp to:10.244.0.18:53
Chain KUBE-SEP-U3UDAUPXUG5BP2NG (2 references)
target prot opt source destination
KUBE-MARK-MASQ all -- box1.ara.ac.nz anywhere /* default/kubernetes:https */
DNAT tcp -- anywhere anywhere /* default/kubernetes:https */ recent: SET name: KUBE-SEP-U3UDAUPXUG5BP2NG side: source mask: 255.255.255.255 tcp to:172.30.0.85:6443
Chain KUBE-SERVICES (2 references)
target prot opt source destination
KUBE-MARK-MASQ tcp -- !10.244.0.0/16 10.96.0.1 /* default/kubernetes:https cluster IP */ tcp dpt:https
KUBE-SVC-NPX46M4PTMTKRN6Y tcp -- anywhere 10.96.0.1 /* default/kubernetes:https cluster IP */ tcp dpt:https
KUBE-MARK-MASQ udp -- !10.244.0.0/16 10.96.0.10 /* kube-system/kube-dns:dns cluster IP */ udp dpt:domain
KUBE-SVC-TCOU7JCQXEZGVUNU udp -- anywhere 10.96.0.10 /* kube-system/kube-dns:dns cluster IP */ udp dpt:domain
KUBE-MARK-MASQ tcp -- !10.244.0.0/16 10.96.0.10 /* kube-system/kube-dns:dns-tcp cluster IP */ tcp dpt:domain
KUBE-SVC-ERIFXISQEP7F7OF4 tcp -- anywhere 10.96.0.10 /* kube-system/kube-dns:dns-tcp cluster IP */ tcp dpt:domain
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-ERIFXISQEP7F7OF4 (1 references)
target prot opt source destination
KUBE-SEP-HZC4RESJCS322LXV all -- anywhere anywhere /* kube-system/kube-dns:dns-tcp */
Chain KUBE-SVC-NPX46M4PTMTKRN6Y (1 references)
target prot opt source destination
KUBE-SEP-U3UDAUPXUG5BP2NG all -- anywhere anywhere /* default/kubernetes:https */ recent: CHECK seconds: 10800 reap name: KUBE-SEP-U3UDAUPXUG5BP2NG side: source mask: 255.255.255.255
KUBE-SEP-U3UDAUPXUG5BP2NG all -- anywhere anywhere /* default/kubernetes:https */
Chain KUBE-SVC-TCOU7JCQXEZGVUNU (1 references)
target prot opt source destination
KUBE-SEP-JNNVSHBUREKVBFWD all -- anywhere anywhere /* kube-system/kube-dns:dns */
Chain WEAVE (0 references)
target prot opt source destination
Chain cali-OUTPUT (0 references)
target prot opt source destination
Chain cali-POSTROUTING (0 references)
target prot opt source destination
Chain cali-PREROUTING (0 references)
target prot opt source destination
Chain cali-fip-dnat (0 references)
target prot opt source destination
Chain cali-fip-snat (0 references)
target prot opt source destination
Chain cali-nat-outgoing (0 references)
target prot opt source destination
Also I can see packets getting dropped on the flannel interface
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1450
inet 10.244.1.0 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::a096:47ff:fe58:e438 prefixlen 64 scopeid 0x20<link>
ether a2:96:47:58:e4:38 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 198 bytes 14747 (14.4 KiB)
TX errors 0 dropped 27 overruns 0 carrier 0 collisions 0
I have installed the same versions of Kubernetes/Docker and Flannel on other VMs and it works, but not sure why I am getting these failed API calls to the master proxy from the worker nodes in this install? I have several fresh installs and tried weave and calico pod networks as well with the same result.
Right so I got this going by changing from flannel to weave container networking, and a kubeadm reset and restart of the VMs.
Not sure what the problem was flannel and my VMs but happy to have got it going.