Allow scheduling of pods on Kubernetes master?

Question

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\

Answer 1

Allow scheduling of pods on the master

kubectl taint node --all node-role.kubernetes.io/master:NoSchedule-

Verify the master isn't tainted

kubectl describe node | egrep -i taint

Taints: <none>

Schedule and run test pod in master

kubectl run -it  busybox-$RANDOM --image=busybox --restart=Never -- date

This answer is a combination of other SO answers, from Victor G, Aryak Sengupta, and others.

Answer 2

I don't know why the master node shows up as NotReady; it shouldn't. Try executing kubectl describe node mymasternode to find out.

The SchedulingDisabled is because the master node is tainted with dedicated=master:NoSchedule

Execute this command against all your masters to remove the taint:

kubectl taint nodes mymasternode dedicated-

To understand why that works read up on taints and tolerations.

Answer 3

Another way to list all taints in nodes and untaint the tainted one.

root@lab-a:~# kubectl get nodes -o json | jq ".items[]|{name:.metadata.name, taints:.spec.taints}"
{
  "name": "lab-a",
  "taints": null
}
{
  "name": "lab-b",
  "taints": [
    {
      "effect": "NoSchedule",
      "key": "node-role.kubernetes.io/master"
    }
  ]
}

lab-a does not have any taint. so we untaint lab-b:

root@lab-a:~# k taint node lab-b node-role.kubernetes.io/master:NoSchedule-
node/lab-b untainted

Install jq in ubuntu by: apt-get install jq

Answer 4

Since Openshift 4.x CoreOs is directly integrated on Kubernetes configuration (you can make all masters schedulable this way

# edit the field spec.mastersSchedulable to set a value true
$ oc patch schedulers.config.openshift.io cluster --type json \
     -p '[{"op": "add", "path": "/spec/mastersSchedulable", "value": true}]'

or using

oc edit schedulers.config.openshift.io cluster 

and edit the field

spec:
    mastersSchedulable: true

Answer 5

First, get the name of the master

kubectl get nodes

NAME     STATUS   ROLES    AGE   VERSION
yasin   Ready    master   11d   v1.13.4

as we can see there is one node with the name of yasin and the role is master. If we want to use it as worker we should run

kubectl taint nodes yasin node-role.kubernetes.io/master-

Answer 6

Use the below command to untaint all masters

kubectl taint nodes --all node-role.kubernetes.io/master-