How to join Kubernetes worker node to Control Plane Node using Vagrant virtual machines

wwillfred

12/3/23, 1:46 AM

I am setting up a Kubernetes cluster using Ubuntu 18.04 virtual machines with Vagrant. All goes well until I try to run the kubeadm join 10.0.2.15:6443 --token ... command on a worker node, and I get the error:

[preflight] Running pre-flight checks
error execution phase preflight: couldn't validate the identity of the API Server: Get "https://10.0.2.15:6443/api/v1/namespaces/kube-public/configmaps/cluster-info?timeout=10s": dial tcp 10.0.2.15:6443: connect: connection refused

My hypothesis is that this is a networking issue, because the IP address that was specified by the kubeadm token create --print-join-command in the Control Plane node was 10.0.2.15:6443, which is not the IP address I had specified for the Control Plan node in the Vagrantfile (172.16.94.10, see below). However, even when I change the kubeadm join command manually like so: sudo kubeadm join 172.16.94.10:6443 --token ..., I get a similar error. How can I resolve this?

Ubuntu system info:

  System load:  0.22              Users logged in:      0
  Usage of /:   4.4% of 97.23GB   IP address for eth0:  10.0.2.15
  Memory usage: 40%               IP address for eth1:  172.16.94.10
  Swap usage:   0%                IP address for tunl0: 192.168.13.192
  Processes:    144

Vagrantfile:

# -*- mode: ruby -*-
# vi: set ft=ruby :
Vagrant.configure("2") do |config|
  config.vm.box = "base"

  config.vm.define "c1-cp1" do |c1cp1|
    c1cp1.vm.box = "bento/ubuntu-18.04"
    c1cp1.disksize.size = '100GB'
    c1cp1.vm.network "private_network", ip: "172.16.94.10"
    c1cp1.vm.hostname = "c1-cp1"
    c1cp1.vm.provider "virtualbox" do |vb|
      vb.memory = "2048"
      vb.cpus = "2"
    end
  end

  config.vm.define "c1-node1" do |c1node1|
    c1node1.vm.box = "bento/ubuntu-18.04"
    c1node1.disksize.size = '100GB'
    c1node1.vm.network "private_network", ip: "172.16.94.11"
    c1node1.vm.hostname = "c1-node1"
    c1node1.vm.provider "virtualbox" do |vb|
      vb.memory = "2048"
      vb.cpus = "2"
    end
  end

end

241

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networking

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kubernetes

Score:0

Ubuntu

wwillfred

12/3/23, 3:18 AM

Per the kubeadm init page, if I start over the process of setting up the Control Plane node and use sudo kubeadm init --apiserver-advertise-address="172.16.94.10" --apiserver-cert-extra-sans="172.16.94.10" instead of the plain sudo kubeadm init, this will configure kubeadm to work with the correct, routable IP address as defined in the Vagrantfile.

I get the result:

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

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EN: How to join Kubernetes worker node to Control Plane Node using Vagrant virtual machines

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