OpenShift 3.5 Installation

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External

Internal

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. This document covers advanced install.

Prerequisites

External DNS Setup

An external DNS server is required. If you control a registrar DNS zone, such as http://godaddy.com, that will work. A valid alternative is to install a dedicated DNS server. The DNS server must be available to all OpenShift environment nodes, and also to external clients than need to resolve public names such as the master public web console and API URL, the application router public DNS name, etc.

If you have different means of resolving public names to clients, a DNS server deployed as part of the environment will work. It can be deployed on the support node.

bind DNS Server

Procedure to configure a bind server:

Set up a bind Server

Wildcard Domain for Application Traffic

The DNS server will need to be capable to support wildcard sub-domains and resolve the public wildcard DNS entry to the public IP address of the node that executes the default router. If the environment has multiple routers, an external load balancer is required, and the wildcard record must contain the public IP address of the host that runs the load balancer. The name of the wildcard domain will be later specified during the advanced installation procedure in the Ansible inventory file as 'openshift_master_default_subdomain'.

For the configuration procedure see:

Declare a Wildcard Subdomain

Minimum Hardware Requirements

https://docs.openshift.com/container-platform/3.5/install_config/install/prerequisites.html#hardware

A full RHEL7.3 master installation requires 121 MB in /boot and an average of 2.4 GB in /. A full RHEL7.3 node installation requires 121 MB in /boot and an average of 2.2 GB in /.

O/S Requirements and Configuration

https://docs.openshift.com/container-platform/3.5/install_config/install/prerequisites.html
https://docs.openshift.com/container-platform/3.5/install_config/install/host_preparation.html

Basic OS

Install RHEL 7.3 in "minimal" installation mode. This document describes the installation in top of a a VirtualBox or VMware Fusion virtual machine.

  • Provision the VM. The procedure to build VirtualBox VMs is described here.
nmcli g

subscription-manager register
subscription-manager list --available --matches '*OpenShift*'
subscription-manager attach --pool=<pool-id> --quantity=1
subscription-manager repos --disable="*"
subscription-manager repos --list-enabled
yum repolist
yum-config-manager --disable <repo_id>
subscription-manager repos --enable="rhel-7-server-rpms" --enable="rhel-7-server-extras-rpms" --enable="rhel-7-server-ose-3.5-rpms" --enable="rhel-7-fast-datapath-rpms"
subscription-manager repos --list-enabled
yum repolist

yum install wget git net-tools bind-utils iptables-services bridge-utils bash-completion
yum update -y
yum install atomic-openshift-utils
  • Prevent accidental upgrades of OpenShiift and Docker, by installing "excluder" packages. The *-excluder packages add entries to the "exclude" directive in the host’s /etc/yum.conf file when installed. Those entries can be removed later when we explicitly want to upgrade OpenShift or Docker. More details in yum Exclusion.
yum install atomic-openshift-excluder atomic-openshift-docker-excluder
  • If later we need to upgrade, we must run the following command:
atomic-openshift-excluder unexclude
  • Reboot the system to make sure it starts correctly after package installation:
systemctl reboot

Installation User

Create an installation user that can log in remotely from support.openshift35.local, which is the host that will drive installation. Conventionally we name that user "ansible" and it must be able to passwordlessly ssh into itself and all other environment nodes, and do passwordless sudo. The user will be part of the shared image. 

groupadd -g 1200 ansible
useradd -m -g ansible -u 1200 ansible

Configure public/private key authentication and install the public key into its own authorized_keys file.

Allow passwordless sudo to "ansible".

Firewall Configuration

Turn off firewalld and configure the iptables service. 

systemctl stop firewalld
systemctl disable firewalld
systemctl is-enabled firewalld

OpenShift needs iptables running: 

systemctl enable iptables
systemctl start iptables

NFS Client

Install NFS client dependencies.

Support Host Configuration

OpenShift Node Configuration

Configure the DNS client to use the DNS server that was installed as part of the procedure. See Manual /etc/resolv.conf Configuration and https://docs.openshift.com/container-platform/3.5/install_config/install/prerequisites.html#prereq-dns

Make sure SELinux is enabled on all hosts. If is not, enable SELinux and make sure SELINUXTYPE is "targeted" in /etc/selinux/config. 

sestatus

Docker Installation

https://docs.openshift.com/container-platform/3.5/install_config/install/host_preparation.html#installing-docker

Install Docker. Docker is technically not required on masters, but it is easier to create a uniform image and only disable docker on masters. The binaries must be installed from the rhel-7-server-ose-3.*-rpms repository and have it running before installing OpenShift.

OpenShift 3.5 requires Docker 1.12. 

yum install docker
docker version

The advanced installation procedure will update /etc/sysconfig/docker on nodes with OpenShift-specific configuration.

After a full 3.5 HA installation, no "--insecure-registry 172.30.0.0/16" was present in the docker startup parameters, so until further notice, add it by hand in /etc/sysconfig/docker. as shown below: 

OPTIONS='... --insecure-registry 172.30.0.0/16'

Provision storage for the Docker server. The default loopback storage is not appropriate for production, it should be replaced by a thin-pool logical volume. Follow https://docs.openshift.com/container-platform/3.5/install_config/install/host_preparation.html#configuring-docker-storage. Used Option A) "an additional block device". On VirtualBox, provision a new virtual disk of appropriate size and configure it as Docker storage backend.

The procedure consists in executing /usr/bin/docker-storage-setup with the base configuration read from /usr/lib/docker-storage-setup/docker-storage-setup and custom configuration specified in /etc/sysconfig/docker-storage-setup, similarly to: 

STORAGE_DRIVER=devicemapper
DEVS=/dev/sdb
VG=docker_vg
DATA_SIZE=500M
MIN_DATA_SIZE=1M

Under some circumstances, /usr/bin/docker-storage-setup fails with: 

[...]
end of partition 1 has impossible value for cylinders: 65 (should be in 0-64)
sfdisk: I don't like these partitions - nothing changed.
(If you really want this, use the --force option.)

If that happens, follow the manual procedure of provisioning Docker storage on a dedicated block device:

Provision Docker Storage on a Dedicated Block Device

After the script completes successfully, it creates a logical volume with an XFS filesystem mounted on docker root directory /var/lib/docker and the Docker storage configuration file /etc/sysconfig/docker-storage. The thin pool to be used by Docker should be visible in lvs: 

# lvs

  LV          VG        Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  docker-pool docker_vg twi-a-t--- 500.00m             0.00   0.88
  root        main_vg   -wi-ao----   7.00g

Disable docker-storage-setup, is not needed, storage already setup. 

systemctl disable docker-storage-setup

Enable Docker at boot and start it. 

systemctl enable docker
systemctl start docker

Reboot the system and then check Docker Server Runtime.

TODO: parse and NOKB this: https://docs.openshift.com/container-platform/3.5/scaling_performance/optimizing_storage.html#optimizing-storage

Generic Docker installation instructions Docker Installation.

Miscellaneous

Cloud-Provider Specific Configuration

Common Image Post-Processing

docker version

lvs

From support.openshift35.local, try: 

ssh -i ~ansible/.ssh/id_rsa ansible@master2

OpenShift Advanced Installation

https://docs.openshift.com/container-platform/latest/install_config/install/advanced_install.html#install-config-install-advanced-install
https://github.com/openshift/openshift-ansible/blob/master/inventory/byo/hosts.ose.example

The Support Node

Execute the installation as "ansible" from the support node. 

cd /usr/share/ansible
chgrp -R ansible /usr/share/ansible
chmod -R g+w /usr/share/ansible

The support node needs at least 1 GB or RAM to run the installation process.

Configure Ansible Inventory File

The default Ansible inventory file is /etc/ansible/hosts. It is used by the Ansible playbook to install the OpenShift environment. The inventory file describes the configuration and the topology of the OpenShift cluster. Start from a template like https://github.com/NovaOrdis/playground/blob/master/openshift/3.5/hosts and customize it to match the environment.

If the target nodes have multiple network interfaces, and the network interface used to cluster OpenShift is NOT associated with the default route, modify the inventory file as follows: 

...
openshift_set_node_ip=true

...
[nodes]
master1.openshift35.local openshift_ip=172.23.0.4 ...

Patch Ansible Logic

External DNS Server Support

OpenShift 3.5 installer did not handle 'openshift_dns_ip' properly, dnsmasq/NewrokManager runtime ignored it. In order to fix it, has to use the following:

Pre-Flight

On the support node:

As "root": 

cd /tmp
rm -r tmp* yum*
rm /usr/share/ansible/openshift-ansible/playbooks/byo/config.retry

As "ansible": 

ansible all -m ping
ansible nodes -m shell -a "docker version"
ansible nodes -m shell -a "nslookup something.apps.openshift35.external"

Running the Advanced Installation

ansible-playbook -vvv /usr/share/ansible/openshift-ansible/playbooks/byo/config.yml

For verbose installation use -vvv or -vvvv.

To use a different inventory file than /etc/ansible/hosts, run: 

ansible-playbook -vvv -i /custom/path/to/inventory/file /usr/share/ansible/openshift-ansible/playbooks/byo/config.yml

Output of a Successful Run

PLAY RECAP *********************************************************************
infranode1.openshift35.local : ok=222  changed=60   unreachable=0    failed=0
infranode2.openshift35.local : ok=222  changed=60   unreachable=0    failed=0
lb.openshift35.local       : ok=75   changed=14   unreachable=0    failed=0
localhost                  : ok=12   changed=0    unreachable=0    failed=0
master1.openshift35.local  : ok=1033 changed=274  unreachable=0    failed=0
master2.openshift35.local  : ok=445  changed=132  unreachable=0    failed=0
master3.openshift35.local  : ok=445  changed=132  unreachable=0    failed=0
node1.openshift35.local    : ok=222  changed=60   unreachable=0    failed=0
node2.openshift35.local    : ok=222  changed=60   unreachable=0    failed=0
support.openshift35.local  : ok=77   changed=5    unreachable=0    failed=0

Verifying the Installation

OpenShift Installation Validation

Uninstallation

In case the installation procedure runs into problems, troubleshoot and before re-starting the installation procedure, uninstall: 

ansible-playbook [-i /custom/path/to/inventory/file] /usr/share/ansible/openshift-ansible/playbooks/adhoc/uninstall.yml

This a relative quick method to iterate over the installation configuration and come up with a stable configuration. However, in order to install a production deployment, you must start from a clean operating system installation. If you are using virtual machines, start from a fresh image. If you are using bare metal machines, run the following on all hosts: 

# yum -y remove openshift openshift-* etcd docker docker-common
# rm -rf /etc/origin /var/lib/openshift /etc/etcd \
    /var/lib/etcd /etc/sysconfig/atomic-openshift* /etc/sysconfig/docker* \
    /root/.kube/config /etc/ansible/facts.d /usr/share/openshift

Post-Install

Deploy a HAProxy Router

In the case there is more than one router pod, the public application traffic, directed to the wildcard domain configured on the external DNS must be handled by a proxy that load balances between the router pods.

This load balancer must be deployed.

TODO

Provision Persistent Storage

https://docs.openshift.com/container-platform/3.5/install_config/persistent_storage/persistent_storage_nfs.html#install-config-persistent-storage-persistent-storage-nfs

TODO

Deploy the Integrated Docker Registry

TODO: isn't this automatically deployed? See "Internal Registry Configuration" section of the inventory file. How do I check?

Load Image Streams

TODO

Load Templates

TODO

Optional Post-Install

Stand-alone Registry

https://docs.openshift.com/container-platform/3.5/install_config/install/stand_alone_registry.html#registry-installation-methods
Stand-alone Registry - Concepts
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