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01-Requirements-and-Preparation.md

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Table of Contents generated with DocToc

Architecture and Requirements

Architecture

The examples in this documentation assume the following architecture. There are three systems:

  • Master + Node
  • Node
  • Node

The master is the scheduler/orchestrator and the API endpoint for all commands. This is similar to V2's "broker". We are also running the node software on the master.

The "node" is just like in OpenShift 2 -- it hosts user applications. The main difference is that "gears" have been replaced with Docker container instances. You will learn much more about the inner workings of OpenShift throughout the rest of the document.

Requirements

Each of the virtual machines should have 4+ GB of memory, 30+ GB of disk space, and the following configuration:

  • RHEL >=7.1 (Note: 7.1 kernel is required for openvswitch)
  • "Minimal" installation option
  • 15-20GB dedicated to /
  • A free/unused partition with the remaining space

The majority of storage requirements are related to Docker and etcd (the data store).

You will need to use subscription manager to both register your VMs, and attach them to the OpenShift Enterprise subscription.

All of your VMs should be on the same logical network and be able to access one another.

In almost all cases, when referencing VMs, you must use hostnames and the hostnames that you use must match the output of hostname -f on each of your nodes. Forward DNS resolution of hostnames is an absolute requirement. This training document assumes the following configuration:

  • ose3-master.example.com (master+node)
  • ose3-node1.example.com
  • ose3-node2.example.com

We do our best to point out where you will need to change things if your hostnames do not match.

If you cannot create real forward resolving DNS entries in your DNS system, you will need to set up your own DNS server on one of the OpenShift nodes. The Appendix chapter has a section on configuring DNSmasq in your environment.

Remember that NetworkManager may make changes to your DNS configuration/resolver/etc. You will need to properly configure your interfaces' DNS settings and/or configure NetworkManager appropriately. See the NetworkManager appendix for more information.

Preparing the Environment

Use a Terminal Window Manager

We strongly recommend that you use some kind of terminal window manager (Screen, Tmux).

DNS

You will need to have a wildcard for a DNS zone resolve, ultimately, to the IP address of the OpenShift router. For this training, we will ensure that the router will end up on the OpenShift server that is running the master. Go ahead and create a wildcard DNS entry for "cloudapps" (or something similar), with a low TTL, that points to the public IP address of your master.

For example:

*.cloudapps.example.com. 300 IN  A 192.168.133.2

You can also use the sample DNSmasq configuration referenced above.

Assumptions

In most cases you will see references to "example.com" and other FQDNs related to it. If you choose not to use "example.com" in your configuration, that is fine, but remember that you will have to adjust files and actions accordingly.

Git

You will either need internet access or read and write access to an internal Git server where you will duplicate the public code repositories used in the labs.

Preparing Each VM

Once your VMs are built and you have verified DNS and network connectivity you can:

  • Configure yum / subscription manager as follows:

      subscription-manager repos --disable="*"
  subscription-manager repos \
  --enable="rhel-7-server-rpms" \
  --enable="rhel-7-server-extras-rpms" \
  --enable="rhel-7-server-optional-rpms" \
  --enable="rhel-7-server-ose-3.1-rpms"

On each VM:

  1. Install deltarpm to make package updates a little faster:

     yum -y install deltarpm

  2. Install useful missing packages (sub tmux for screen if you wish):

     yum -y install wget vim-enhanced net-tools bind-utils tmux git

  3. Install the installer:

     yum -y install atomic-openshift-utils

  4. Update:

     yum -y update

Docker Storage Setup (optional, recommended)

IMPORTANT: The default Docker storage configuration uses loopback devices and is not appropriate for production. Red Hat considers the dm.thinpooldev storage option to be the only appropriate configuration for production use at this time.

If you want to configure the storage for Docker, you'll need to first install Docker, as the installer currently does not auto-configure this storage setup for you.

yum -y install docker

Make sure that you are running at least docker-1.8.2-8.el7.

Please see the OpenShift documentation on configuring Docker storage:

https://docs.openshift.com/container-platform/latest/install_config/install/host_preparation.html#configuring-docker-storage

Grab Docker Images (optional, recommended)

If you want to pre-fetch Docker images to make the first few things in your environment happen faster, you'll need to first install Docker if you didn't install it when (optionally) configuring the Docker storage previously.

yum -y install docker

Make sure that you are running at least docker-1.8.2-8.el7, then:

systemctl start docker

On all of your systems, grab the following docker images:

docker pull registry.access.redhat.com/openshift3/ose-haproxy-router:v3.1.0.4
docker pull registry.access.redhat.com/openshift3/ose-deployer:v3.1.0.4
docker pull registry.access.redhat.com/openshift3/ose-sti-builder:v3.1.0.4
docker pull registry.access.redhat.com/openshift3/ose-docker-builder:v3.1.0.4
docker pull registry.access.redhat.com/openshift3/ose-pod:v3.1.0.4
docker pull registry.access.redhat.com/openshift3/ose-docker-registry:v3.1.0.4
docker pull registry.access.redhat.com/openshift3/ose-keepalived-ipfailover:v3.1.0.4

It may be advisable to pull the following Docker images as well, since they are used during the various labs:

docker pull registry.access.redhat.com/rhscl/ruby-22-rhel7
docker pull registry.access.redhat.com/rhscl/mysql-56-rhel7
docker pull registry.access.redhat.com/rhscl/php-56-rhel7
docker pull registry.access.redhat.com/jboss-eap-6/eap-openshift
docker pull openshift/hello-openshift:v1.0.6

Clone the Training Repository

On your master, it makes sense to clone the training git repository:

cd
git clone https://github.com/openshift/training.git

REMINDER Almost all of the files for this training are in the training folder you just cloned.

Add Development Users

In the "real world" your developers would likely be using the OpenShift tools on their own machines (oc and the web console). For these examples, we will create user accounts for two non-privileged users of OpenShift, joe and alice, on the master. This is done for convenience and because we'll be using htpasswd for authentication.

useradd joe
useradd alice

We will come back to these users later. Remember to do this on the master system, and not the nodes.

Useful OpenShift Logs

RHEL 7 uses systemd and journal. As such, looking at logs is not a matter of /var/log/messages any longer. You will need to use journalctl.

Since we are running all of the components in higher loglevels, it is suggested that you use your terminal emulator to set up windows for each process. If you are familiar with the Ruby Gem, tmuxinator, there is a config file in the training repository. Otherwise, you should run each of the following in its own window:

journalctl -f -u atomic-openshift-master
journalctl -f -u atomic-openshift-node

Note: You will want to do this on the other nodes, but you won't need the "-master" service. You may also wish to watch the Docker logs, too.

Note: There is an appendix on configuring Log Aggregation