Introduction

OpenShift OKD is a container management platform built through the RedHat community, based on Kubernetes. OpenShift takes care of many CI/CD processes that developers typically undertake when deploying containers to platforms such as Kubernetes. In this brief article, I’ll describe the process in setting up a basic OpenShift cluster, loging into to the cluster cli, configuring the initial user roles and deploying your first OpenShift project.

Reference Architecture

To get started, you will need a number of servers configured, with SSH access via key auth to all of them, so please make sure you share your public ssh key amongst them.

Openshift Masters

OpenShift Nodes

OpenShift Infrastructure Nodes

OpenShift HAProxy

Getting Started

Firstly, you need to ensure each host can be referenced through DNS, so it is highly desirable to have a DNS environment in which you can add A records for each host. In addition to A Records for the hosts, an A Record / CNAME is required for the OpenShift Cluster address which ultimately points to the HAProxy IP address. Finally, a wildcard DNS entry is required for the OpenShift router (in our example, hosts on the Infrastructure node) such as:

*.openshift.local.lan

Throughout this guide, I’ll be using the HAProxy server to run the deployment from - feel free to use an appropriate jumpbox / management server instead if you have on available.

On the HAProxy, we’ll start by doing the basics and ensure our environment is up to date and contains the useful stuff:

$ yum update -y
$ yum install vim -y

Next we’ll generate an ssh key pair, and copy the public key to each of the servers:

$ ssh-keygen
$ ssh-copy-id root@<server>

with that done, we’ll move onto the deployment.

Deployment

On the HAProxy / management server:

$ yum update
$ yum install vim git epel-release

And now we’ll download the OpenShift ansible playbooks from github, and checkout the correct version:

$ git clone https://github.com/openshift/openshift-ansible.git
$ cd openshift-ansible/
$ git checkout release-3.11

Next we will make a backup of the example inventory file, and ammend it to our needs

$ cp inventory/hosts.example inventory/hosts.custom
$ vim inventory/hosts.custom

We need to add the following:

openshift_disable_check=docker_image_availability,memory_availability

$ yum -y install ansible-2.6.5

At this point, if you are using a hyper visor such as VMWare or Hyper-V, I would recommend taking a snapshot or checkpoint. Similarly, if you are using a public cloud provider such as AWS, take an EBS snapshot etc.

ansible-playbook -i inventory/hosts.custom playbooks/prerequisites.yml

ansible-playbook -i openshift-ansible/inventory/hosts.custom openshift-ansible/playbooks/deploy_cluster.yml

Once the playbook has completed without error, it’s time to switch over to one of the master nodes:

ssh root@osm1.local.lan

Once logged in, we’ll check that OpenShift is running:

$ oc get pods --all-namespaces
NAMESPACE        NAME                                  READY     STATUS    RESTARTS   AGE
kube-system      master-api-osm1.local.lan          1/1       Running   0          22m
kube-system      master-api-osm2.local.lan           1/1       Running   0          22m
kube-system      master-api-osm3.local.lan           1/1       Running   1          22m
kube-system      master-controllers-osm1.local.lan   1/1       Running   0          22m
kube-system      master-controllers-osm2.local.lan   1/1       Running   0          22m
kube-system      master-controllers-osm3.local.lan   1/1       Running   0          22m
kube-system      master-etcd-osm1.local.lan          1/1       Running   1          29m
kube-system      master-etcd-osm2.local.lan          1/1       Running   1          28m
kube-system      master-etcd-osm3.local.lan          1/1       Running   1          28m
openshift-node   sync-79hhm                            1/1       Running   0          17m
openshift-node   sync-8b6d4                            1/1       Running   0          17m
openshift-node   sync-h6rw4                            1/1       Running   0          17m