kubernetes service IPs not reachable

Question

So I\'ve got a Kubernetes cluster up and running using the Kubernetes on CoreOS Manual Installation Guide.

$ kubectl get no
NAME              STATUS                   


        

Answer 1

I had this same problem, and the ultimate solution that worked for me was enabling IP forwarding on all nodes in the cluster, which I had neglected to do.

$ sudo sysctl net.ipv4.ip_forward=1
net.ipv4.ip_forward = 1

Service IPs and DNS started working immediately afterwards.

Answer 2

I had the same issue, turned out to be a configuration issue in kube-proxy.yaml For the "master" parameter I had the ip address as in - --master=192.168.3.240 but it actually required to be a url like - --master=https://192.168.3.240

FYI my kube-proxy sucessfully uses --proxy-mode=iptables (v1.6.x)

Answer 3

The Sevice network provides fixed IPs for Services. It is not a routeable network (so don't expect ip ro to show anything nor will ping work) but a collection iptables rules managed by kube-proxy on each node (see iptables -L; iptables -t nat -L on the nodes, not Pods). These virtual IPs (see the pics!) act as load balancing proxy for endpoints (kubectl get ep), which are usually ports of Pods (but not always) with a specific set of labels as defined in the Service.

The first IP on the Service network is for reaching the kube-apiserver itself. It's listening on port 443 (kubectl describe svc kubernetes).

Troubleshooting is different on each network/cluster setup. I would generally check:

• Is kube-proxy running on each node? On some setups it's run via systemd and on others there is a DeamonSet that schedules a Pod on each node. On your setup it is deployed as static Pods created by the kubelets thrmselves from /etc/kubernetes/manifests/kube-proxy.yaml
• Locate logs for kube-proxy and find clues (can you post some?)
• Change kube-proxy into userspace mode. Again, the details depend on your setup. For you it's in the file I mentioned above. Append --proxy-mode=userspace as a parameter on each node
• Is the overlay (pod) network functional?

If you leave comments I will get back to you..