Easy to configure the Openshift Cluster OKD (3.11) on CentOS

In my demo environment, I am going to build a openshift cluster -- one master node (master/Infra/computer node) and two computer nodes. Any comments are welcome!

System requirements to configure the environment:
Master node: 4 vcpu/32GB mem
Compuer node: 2 vcpu/ 16GB mem

The following steps (1-4) will be done on all nodes as root

1> Create a user on all NODES (any user account you prefer)

useradd origin
passwd origin

2> Grant the sudo access without password for this user on all NODES

echo -e 'Defaults:origin !requiretty\norigin ALL = (root) NOPASSWD:ALL' | tee /etc/sudoers.d/openshift
chmod 440 /etc/sudoers.d/openshift 

3> Open firewall on all NODES

firewall-cmd --add-service=ssh --permanent
firewall-cmd --reload

4> Install Openshift, EPEL, Docker, Git abd Py on all NODES

yum -y install centos-release-openshift-origin311 epel-release docker git pyOpenSSL
systemctl start docker 
systemctl enable docker

Please make a note: The following steps will be done only on the master node as the user account you created.

5> Configure the SSH key pair and ssh each node without password as the the user
ssh-keygen -q -N "" 
vi ~/.ssh/config

# create new ( define each node )

Host master
    Hostname master
    User origin
Host node01
    Hostname node01
    User origin
Host node02
    Hostname node02
    User origin

(please make note, master/node1/node2 can be pinged each other by adding into either DNS or localhost)

chmod 600 ~/.ssh/config
ssh-copy-id node01 
ssh-copy-id node02
ssh-copy-id master

6> Install/configure the ansible playbook for the openshift cluster as the user
sudo yum -y install openshift-ansible

sudo vi /etc/ansible/hosts

# add follows to the end

[OSEv3:children]
masters
nodes
etcd

[OSEv3:vars]
# admin user created in previous section
ansible_ssh_user=origin
ansible_become=true
openshift_deployment_type=origin

# use HTPasswd for authentication
openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true', 'challenge': 'true', 'kind': 'HTPasswdPasswordIdentityProvider'}]
# define default sub-domain for Master node
openshift_master_default_subdomain=apps.eteck.com
# allow unencrypted connection within cluster
openshift_docker_insecure_registries=172.30.0.0/16

[masters]
master.eteck.com openshift_schedulable=true containerized=false

[etcd]
master.eteck.com

[nodes]
# defined values for [openshift_node_group_name] in the file below
# [/usr/share/ansible/openshift-ansible/roles/openshift_facts/defaults/main.yml]
master.eteck.com openshift_node_group_name='node-config-master-infra'
node01.eteck.com openshift_node_group_name='node-config-compute'
node02.eteck.com openshift_node_group_name='node-config-compute'

# if you'd like to separate Master node feature and Infra node feature, set like follows
# master.eteck.com openshift_node_group_name='node-config-master'
# node01.eteck.com openshift_node_group_name='node-config-compute'
# node02.eteck.com openshift_node_group_name='node-config-infra'

Please make  a note: the apps.eteck.com is sub-domain and all IP addresses of hosts under this sub-domain point to the ip address of master

7> run Prerequisites Playbook
ansible-playbook --ask-pass --ask-sudo-pass /usr/share/ansible/openshift-ansible/playbooks/prerequisites.yml 

8> Run the deploy Cluster playbook
ansible-playbook --ask-pass --ask-sudo-pass /usr/share/ansible/openshift-ansible/playbooks/deploy_cluster.yml

(Please make a note: I did not use the default filesysem, I used the ext4 which did not pass the docker storage check. So I use "-e openshift_disable_check=docker_storage" to skip the check.) Here is the command:

ansible-playbook --ask-pass --ask-sudo-pass /usr/share/ansible/openshift-ansible/playbooks/deploy_cluster.yml -e openshift_disable_check=docker_storage

Verify after done:

[origin@osmaster ~]$ oc get nodes
NAME       STATUS    ROLES          AGE       VERSION
osmaster   Ready     infra,master   3h        v1.11.0+d4cacc0
osnode01   Ready     compute        3h        v1.11.0+d4cacc0
osnode02   Ready     compute        3h        v1.11.0+d4cacc0
[origin@osmaster ~]$ oc get nodes --show-labels=true 
NAME       STATUS    ROLES          AGE       VERSION           LABELS
osmaster   Ready     infra,master   3h        v1.11.0+d4cacc0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=osmaster,node-role.kubernetes.io/infra=true,node-role.kubernetes.io/master=true
osnode01   Ready     compute        3h        v1.11.0+d4cacc0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=osnode01,node-role.kubernetes.io/compute=true

osnode02   Ready     compute        3h        v1.11.0+d4cacc0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=osnode02,node-role.kubernetes.io/compute=true