Setting up an OpenShift 4 Lab cluster via Ansible

Introduction

This document described how to install a Red Hat OpenShift 4 Cluster on a Lab environment.

The lab environment consists of the following parts:

• 4 Bare-Metal machines with 16 GB RAM and 2x SSDs (128 GB and 256 GB) each
• 1 Bastion host with 4 GB RAM and 2x SSDs (250 GB and 500 GB)
• 1 Gigabit Switch
• 1 WLAN-Router
• 1 KVM switch
• 1 LCD-Panel
• USB keyboard and mouse connected to KVM switch
• 1 toolbox (to contain the lab)

Steps

Setup WLAN router

The WLAN router needs to have the following configuration settings:

• Disable DHCP (this will be done via the Bastion host later)
• Define the following DNS servers
  • 8.8.8.8
  • <IP of Bastion Host>

Setup BIOS

In order for automation to work you need to configure the BIOS of the master and worker nodes to use the following features:

• Boot from Ethernet device
• Wake-On-LAN (usually hidden in ACPI settings)

Setup Bastion host

Create a Bastion host with Red Hat Enterprise Linux 8.1 (or higher) and use subscription-manager to entitle the system.

Also you need to install Ansible via yum install -y ansible

Get IP/MAC-Addresses

For creating the Ansible inventory file you will need to define IP addresses for the masters, workers, and bootstrap node.

Get an offline access token

Go to https://cloud.redhat.com/openshift/token and request an offline access token. This is needed later for requesting the pull secrets for mirroring container images.

Create inventory file

Now create an Ansible inventory file named ocp4labs-inventory with the following content (adjust as you see fit):

[ocp4labs:children]
bastion
kvm
masters
workers
bootstrap

[ocp4labs:vars]
host_key_checking = False
ansible_ssh_private_key_file=~/.ssh/id_ocplabs
ansible_ssh_user=root
ocp4_release=4.3.3
ocp4_release_name=ocp-release
ocp4_type=bare-metal
ocp4_cluster_name=<cluster-name>
ocp4_cluster_domain_name=<cluster-domain-name>
rhcos_release=4.3.0

# Taken from https://cloud.redhat.com/openshift/token
ocp4_offline_access_token=<offline-access-token>

[all]
master01 ansible_host=<node-ip> ethernet="<node-mac>" kvm_host=kvm01
master02 ansible_host=<node-ip> ethernet="<node-mac>" kvm_host=kvm02
master03 ansible_host=<node-ip> ethernet="<node-mac>" kvm_host=kvm03
worker01 ansible_host=<node-ip> ethernet="<node-mac>" kvm_host=kvm01
worker02 ansible_host=<node-ip> ethernet="<node-mac>" kvm_host=kvm02
worker03 ansible_host=<node-ip> ethernet="<node-mac>" kvm_host=kvm03
bastion ansible_host=<node-ip> ethernet="<node-mac>"

[bastion]
bastion

[kvm]
kvm01
kvm02
kvm03

[masters]
master01
master02
master03

[workers]
worker01
worker02
worker03

[bootstrap]
worker01

Create SSH keys

ssh-keygen -f ~/.ssh/id_ocplabs

cat ~/.ssh/authorized_keys <Content of ~/.ssh/id_ocplabs.pub>

cat ~/.ssh/config IdentityFile ~/.ssh/id_ocplabs

Run Ansible playbook

Now you are ready to run the Ansible playbook as follows:

ansible-playbook -vvv -i ocp4labs-inventory ocp4labs.yml

Depending on the hardware available and speed of the internet connection this may take a while, so grab a coffee or cook yourself a good meal. Soon you will have a fully functional OpenShift 4 Cluster up-and-running to play around with.