Install openshift origin 3.11 cluster on a single virtualbox VM running CentOS 7

The minimum requirements for openshift origin (OKD) 3.11 is at least 16GB memory, but since my machine does not have that much capacity, I just use 8GB memory, and exclude all hardware checks in my inventory file

For openshift installation to run smoothly, you need a proper, separate DNS server. Refer to my previous post, on how to setup a very easy DNS server. The DNS can be installed in another VM with probably 512MB memory.

Prepare a VM, with:
- 8GB memory
- 50GB hardisk
- 1 vcpu
- bridged network

Install centos 7 on the VM

Since we are going to use ansible, passwordless ssh is necessary, even though it is just only one machine
# ssh-keygen
# ssh-copy-id localhost

Update the operating system, and install base packages
# yum update -y; yum install wget git net-tools bind-utils yum-utils iptables-services bridge-utils bash-completion kexec-tools sos psacct -y; reboot

Install epel repository, and disable the repo by default
# yum install -y epel-release; sed -i 's/enabled=1/enabled=0/' /etc/yum/repos.d/epel.repo

Install ansible and pyOpenSSL
# yum install -y --enablerepo=epel ansible pyOpenSSL

Install docker
# yum install -y docker-1.13.1

Install, enable and restart NetworkManager

# yum install NetworkManager -y

# systemctl enable NetworkManager

# systemctl start NetworkManager

Clone the openshift-origin repository in github. This repository will provide required playbooks and configuration files
# cd
# git clone https://github.com/openshift/openshift-ansible
# cd openshift-ansible
# git checkout release-3.11

Generate a hashed password for your first user

# openssl passwd -apr1 typeyourpasswordhere

Prepare your inventory file. You can refer here for the meaning of each options in below inventory file. Make sure that every hostname used in this file is DNS resolvable 

# cat > ~/openshift-ansible/inventory.ini <<EOF

[OSEv3:children]

masters

nodes

etcd

[OSEv3:vars]

ansible_ssh_user=root

openshift_deployment_type=origin

'kind': 'HTPasswdPasswordIdentityProvider'}]

openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true', 'challenge': 'true', 'kind': 'HTPasswdPasswordIdentityProvider'}]

openshift_master_htpasswd_users={'admin': '$apr1$qpJB3Cls$PN7/HlUNqBXikBl.jnrHF.'}

openshift_public_hostname=console.local.my

openshift_master_default_subdomain=apps.console.local.my

openshift_disable_check=disk_availability,docker_storage,memory_availability,docker_image_availability

[masters]

osmaster.local.my openshift_schedulable=true 

[etcd]

osmaster.local.my 

[nodes]

osmaster.local.my openshift_schedulable=true openshift_node_group_name="node-config-all-in-one"

EOF

Run the prerequisites.yml playbook. This playbook will install required for openshift installation
# cd ~/openshift-ansible
# ansible-playbook -i inventory.ini playbooks/prerequisites.yml

Run the deployment playbook to deploy your openshift cluster
# ansible-playbook -i inventory.ini playbooks/deploy_cluster.yml

Once installation is complete, verify your installation by checking on the nodes
# oc get nodes

and logging in to openshift webconsole which in this case is https://console.local.my:8443, providing the username and password as per in your inventory.ini file