How to set up a CoreOS Cluster on Windows and CentOS

This post deals with setting up a 3-Cluster CoreOS installation using Vagrant and VirtualBox on Windows and CentOS. It is intended as a short practical introduction to using CoreOS. Later posts will show how to set up and connect different containers in CoreOS.

Why use CoreOS?

The new architecture of ePages will almost certainly be based on CoreOS as an operating system. CoreOS in combination with Docker, etcd, systemd or fleet fits perfectly into the microservices approach. It is designed to facilitate large multiple-machine deployments and is easy to scale and manage. CoreOS uses Linux containers to manage services instead of package managers. One of the main advantages is that the code and all dependencies of a single service, is packaged within a container and can be run on different CoreOS machines (see also Using CoreOs and CoreOS with Docker).

Now let’s just start with the practical stuff:

Windows

Prerequisites

1. Power Shell 3.0

First, install the Windows Management Framework 3.0 including the Windows PowerShell 3.0. The standard shell will have some troubles with paths. Download the latest version here.

2. Install cygwin

To get the rsync feature, install cygwin on your Windows installation. Download it here.

• Make sure to activate “rsync” and “SSH” in the installation.
• Add “C:\cygwin64\bin” to your Windows system variable “PATH”.

3. Install VirtualBox

Download the latest version of VirtualBox here.

4. Install Vagrant

Download the latest version of Vagrant here.

Getting started

1. Clone the CoreOs-Vagrant git repo

Make sure to use Git in Bash for this.

$ git clone https://github.com/coreos/coreos-vagrant.git
$ cd coreos-vagrant

2. Start a cluster

We need to generate a unique token where etcd can find information on the nodes of the etcd cluster.

• Get the discovery token from https://discovery.etcd.io/new
• Edit the file user-data. Replace https://discovery.etcd.io/NEW_TOKEN with the URL received above.

etcd2:
  discovery: https://discovery.etcd.io/NEW_TOKEN

After replacing the link it should looks like this:

etcd2:
  discovery: https://discovery.etcd.io/0850c01e29cb6d7dcd5d4e9123311704

3. Start clusters

Now change to your PowerShell 3.0 and execute the following commands:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant up

If everything works fine three VirtualBox windows appear and your shell should look like this:

4. Stop clusters

To stop the clusters execute the following commands in your PowerShell 3.0:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant halt

5. Increase cluster count

To increase the count of clusters, change the file config.rb. Let’s try to set up CoreOs with 10 clusters just for fun.

Change this:

# Size of the CoreOs cluster created by Vagrant
$num_instances=3

to this:

# Size of the CoreOs cluster created by Vagrant
$num_instances=10

Now switch to your PowerShell 3.0 and execute the following commands:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant up

If everything works properly, you should see something like this:

6. Remove clusters

To completely remove the clusters, execute the following commands in PowerShell 3.0:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant destroy

CentOS

Prerequisites

1. Install git

$ yum install git

2. Install openssl-devel and openssl-devel

$ yum install openssl-devel openssl

3. Install nano

$ yum install nano

4. Install Vagrant

See also.

$ cd
$ mkdir downloads
$ cd downloads
$ cd wget https://dl.bintray.com/mitchellh/vagrant/vagrant_1.7.4_x86_64.rpm
$ rpm -Uvh vagrant_1.7.4_x86_64.rpm

5. Install VirtualBox

See also.

$ vim /etc/yum.repos.d/virtualbox.repo

Insert the following text:

[virtualbox]
name=Oracle Linux / RHEL / CentOS-$relesever / $basearch - VirtualBox
baseurl=http://download.virtualbox.org/virtualbox/rpm/el/$releasever/$basearch
enabled=1
gpgcheck=1
gpgkey=http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc

Save and exit vim.

Execute this:

$ rpm -Uvh http://ftp.joist.ac.jp/pub/Linux/Fedora/epel/7/x86_64/e/epel-release-7-5.noarch.rpm
$ yum install gcc make patch dkms qt libgomp
$ yum install kernel-headers kernel-devel fontforge binutils glibc-headers glibc-devel
$ export KERN_DIR=/usr/src/kernels/2.6.32-504.3.3.el6.x86_64
$ yum install VirtualBox-5.0
$ service vboxdrv setup

Getting started

1. Clone the CoreOs-Vagrant git repo

Use Git in Bash for this.

$ cd ./git-projects-github/
$ git clone https://github.com/coreos/coreos-vagrant.git
$ cd coreos-vagrant

2. Start a cluster

We need to generate a unique token where etcd can find information on the nodes of the etcd cluster.

• Get the discovery token from https://discovery.etcd.io/new
• Edit the file user-data. Replace https://discovery.etcd.io/NEW_TOKEN with the URL received above.

$ cd ./git-projects-github/coreos-vagrant
$ nano user-data

etcd2:
  discovery: https://discovery.etcd.io/NEW_TOKEN

After replacing the link it should looks like this:

etcd2:
  discovery: https://discovery.etcd.io/0850c01e29cb6d7dcd5d4e9123311704

3. Start clusters

$ cd .\git-projects-github\coreos-vagrant
$ vagrant up

4. Stop clusters

To stop the clusters, execute the following commands in PowerShell 3.0:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant halt

5. Increase cluster count

To increase the count of clusters, change the file config.rb. Let’s try to set up CoreOs with 10 clusters just for fun.

$ cd .\git-projects-github\coreos-vagrant
$ nano config.rb

Change this:

# Size of the CoreOs cluster created by Vagrant
$num_instances=3

to this:

# Size of the CoreOs cluster created by Vagrant
$num_instances=10

Execute the following commands to start the clusters:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant up

6. Remove clusters

To completely remove the clusters, execute following commands:

$ cd .\git-projects-github\coreos-vagrant
$ vagrant destroy

Troubleshooting

Install nfs (if required)

$ yum install nfs-utils nfs-utils-lib

Related links

• UsingCoreOS
• CoreOSTutorial
• CoreOSVagrantRepo

About the author

Andreas G. belongs to the epagesdevs content team.