/vm-kube

Kubernetes in CentOS on VirtualBox

A workflow for setting up a Kubernetes cluster using 3 VMs, a master and 2 workers.

Setup

The first section assumes you have VirtualBox installed and a CentOS 7.5 Minimal iso on hand.

  1. Create Host Only Adapter (IP: 192.168.56.1/24 & No DHCP)
  2. Create 1 Master VM
    • VirtualBox Settings
      • 1st network adapter set to Host Only
      • 2nd network adapter set to NAT
    • CentOS install settings:
      • Set timezone
      • Networking disabled and unconfigured
      • No users besides root
  3. Create 2 Worker VMs
    • VirtualBox Settings
      • 1st network adapter set to Host Only
    • CentOS install settings:
      • Set timezone
      • Networking disabled and unconfigured
      • No users besides root
  4. Configure networking
    • Master
      • nmcli con add type ethernet con-name wan-con ifname enp0s8
      • nmcli con add type ethernet con-name lan-con ifname enp0s3 ip4 192.168.56.101/24
      • Option 1: IPTables
        • systemctl stop firewalld && systemctl disable firewalld
        • yum install -y iptables-services
        • systemctl enable iptables.service
        • echo 'net.ipv4.ip_forward = 1' >> /etc/sysctl.conf
        • sysctl -p /etc/sysctl.conf
        • iptables -A FORWARD -i enp0s3 -j ACCEPT
        • iptables -A FORWARD -o enp0s3 -j ACCEPT
        • iptables -t nat -A POSTROUTING -o enp0s8 -j MASQUERADE
        • service iptables save
      • Option 2: Firewalld
        • nmcli con mod lan-con connection.zone internal
        • nmcli con mod wan-con connection.zone external
        • nmcli con up lan-con
        • nmcli con up wan-con
    • Worker 1
      • nmcli con add type ethernet con-name lan-con ifname enp0s3 ip4 192.168.56.102/24 gw4 192.168.56.101 ipv4.dns 8.8.8.8
      • nmcli con up lan-con
    • Worker 2
      • nmcli con add type ethernet con-name lan-con ifname enp0s3 ip4 192.168.56.103/24 gw4 192.168.56.101 ipv4.dns 8.8.8.8
      • nmcli con up lan-con
  5. Set hostnames
    • Master: hostnamectl set-hostname kmaster
    • Worker 1: hostnamectl set-hostname kworker1
    • Worker 2: hostnamectl set-hostname kworker2
  6. Create "centos" user on master
    • adduser centos
    • passwd centos
    • usermod -aG wheel centos
  7. Configure keys for SSH
    • on local machine:
      • ssh-copy-id root@192.168.56.101
      • ssh-copy-id centos@192.168.56.101
      • ssh-copy-id root@192.168.56.102
      • ssh-copy-id root@192.168.56.103

Ansible

This section uses the provided Ansible YML files to install Kubernetes on the 3 nodes.

  1. Change values in hosts file
  2. ansible-playbook -i hosts kube-dependencies.yml
  3. ansible-playbook -i hosts master.yml
  4. Check master node is ready
    • ssh centos@master_ip
    • kubectl get nodes
  5. ansible-playbook -i hosts workers.yml
  6. Check workers have joined
    • ssh centos@master_ip
    • kubectl get nodes

References

Much of the ansible yml was used from the following: