Allow scheduling of pods on Kubernetes master?
I set up Kubernetes on CoreOS on bare metal using the generic install scripts. It's running the current stable release, 1298.6.0, with Kubernetes version 1.5.4.
We'd like to have a highly available master setup, but we don't have enough hardware at this time to dedicate three servers to serving only as Kubernetes masters, so I would like to be able to allow user pods to be scheduled on the Kubernetes master. I set --register-schedulable=true in /etc/systemd/system/kubelet.service but it still showed up as SchedulingDisabled.
I tried to add settings for including the node as a worker, including adding worker TLS certs to /etc/kubernetes/ssl, adding those settings to kubelet.service, adding an /etc/kubernetes/worker-kubeconfig.yaml that pointed to those certs, and added that information to the /etc/kubernetes/manifests/kube-proxy.yaml. I used my existing nodes as a template for what to add. This registered another node under the master's hostname and then both it and the original master node showed up as NotReady,SchedulingDisabled.
This question indicates that scheduling pods on the master node should be possible, but there is barely anything else that I can find on the subject.
Answer
If you are using Kubernetes 1.7 and above:
kubectl taint node mymasternode node-role.kubernetes.io/master:NoSchedule-