OpenShift Installation

External

• https://install.openshift.com/

Internal

• OpenShift

Overview

There are two installation methods: quick install, which uses a CLI tool available in the "atomic-openshift-utils" package, which, in turn, uses Ansible in the background, and advanced install. The advanced install assumes familiarity with Ansible.

Prerequisites

System Requirements

Relevance OpenShift 3.3.

Master

• Physical or virtual system.
• RHEL 7.1 installed with the "minimal" installation option.
• 2 CPUs
• 8 GB RAM
• 30 GB storage space.

Node

• Physical or virtual system.
• RHEL 7.1 installed with the "minimal" installation option.
• 1 CPU
• 8 GB RAM
• 15 GB storage space.
• Docker 1.9.1 or later
• 15 GB to allocated to Docker storage.

External DNS Setup

An external DNS server is required.

After setup, the DNS server needs to be configured to resolve a public wildcard DNS entry to the public IP address of the node that executes the default router, by adding an A record, with a low TTL. If the environment has multiple routers, an external load balancer is required.

*.myapp.example.com. 300 IN  A 1.2.3.4

O/S Installation

Execute a minimal installation on one host, and perform the following steps. Then the same image can be used for as a base for the other nodes.

Register all hosts with Red Hat Subscription Manager to RHEL 7.x and OpenShift 3 repositories.

Extra packages required:

yum install wget git net-tools bind-utils iptables-services bridge-utils bash-completion
yum update -y

Turn off firewalld and configure the iptables service

• Make sure master can issue remote commands on the nodes without requiring password. Ansible, who runs the installation process, requires a user that has password-less access to all hosts.

From the master, as root:

# ssh-keygen
# ssh-copy-id root@node1.example.com

• Configure iptables. iptables must be running and the following ports must be open. Most of the ports will be configured by the installer, automatically - verify that.:

OpenShift Ports

Install Docker

A Docker that works with OpenShift must be installed from rhel-7-server-ose-3.2-rpms and have it running on master and all nodes before installing OpenShift. Version requirements are specified in Prerequisites.

yum install docker

Edit /etc/sysconfig/docker and add:

OPTIONS=--selinux-enabled --insecure-registry 172.30.0.0/16

--insecure-registry instructs Docker daemon to trust any Docker registry on 172.30.0.0/16 subnet without requiring a certificate.

The default loopback storage is not appropriate for production, it should be replaced by a thin-pool logical volume. Use the docker-storage-setup script:

• The script reads configuration options from /etc/sysconfig/docker-storage-setup.
• Reinitialized Docker before starting docker-storage-setup:

systemctl stop docker
rm -rf /var/lib/docker/*

• Execute docker-storage-setup to create thin-pool volume free space in the volume group where the root filesystem resides.
• Use the existing volume group to create thin-pool:

# cat /etc/sysconfig/docker-storage-setup
DEVS=/dev/vdb
VG=docker-vg
# docker-storage-setup

Generic installation instructions:

Docker Installation

Post-Install

Set up NFS

The NFS server is required for persistent volumes.