An extracted part of a Chef recipe to deploy Kubernetes with Kubeadm logging in real-time the command output

master.rb

require 'pty'

# Initialize master
ruby_block 'kubeadm init' do
  block do
    command = <<-CMD
      kubeadm init \
      --token=#{node['kubeadm']['token']} \
      --pod-network-cidr=#{node['kubeadm']['pod_cidr']} \
      --service-cidr=#{node['kubeadm']['service_cidr']} \
      --service-dns-domain=#{node['kubeadm']['dns_domain']} \
      --apiserver-advertise-address=#{node['kubeadm']['api_ip_address']}
    CMD

    PTY.spawn(command) do |stdout, _, _|
      begin
        loop { puts stdout.gets.gsub(/\r\n/, '').gsub(/\t/, '  ') }
      rescue Errno::EIO
      end
    end
  end
  action :run
  not_if "grep 'https://#{master_ip_address}' /etc/kubernetes/kubelet.conf"
end