CentOS 7
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OpenStack Pike : Pre-Requirements
This is the exmaple of Cloud Computiong by OpenStack Pike.
Install some services that some components of OpenStack needs for system requirements on here.
This example is based on the emvironment like follows.
          |    [ Control Node ]   |
          |                       |
          |  MariaDB    RabbitMQ  |
          |  Memcached            |

[2] Add the repository of Openstack Pike.
[[email protected] ~]#
yum -y install centos-release-openstack-pike

[[email protected] ~]#
sed -i -e "s/enabled=1/enabled=0/g" /etc/yum.repos.d/CentOS-OpenStack-pike.repo

[3] Install MariaDB server.
It's possible to use MariaDB 5.5 on CentOS Base repository though, but on this exmaple, Install MariaDB 10.1 provided from CentOS Release Openstack Newton above.
After installation, Configure basic settings, refer to here.
# install from Openstack Pike

[[email protected] ~]#
yum --enablerepo=centos-openstack-pike -y install mariadb-server
[4] Install RabbitMQ, Memcached.
# install from EPEL

[[email protected] ~]#
yum --enablerepo=epel -y install rabbitmq-server memcached
[[email protected] ~]#
systemctl start rabbitmq-server memcached

[[email protected] ~]#
systemctl enable rabbitmq-server memcached

# add openstack user (set any password you like for "password")

[[email protected] ~]#
rabbitmqctl add_user openstack password

Creating user "openstack" ...
[[email protected] ~]#
rabbitmqctl set_permissions openstack ".*" ".*" ".*"

Setting permissions for user "openstack" in vhost "/" ...
[5] If Firewalld is running, allow ports for services.
[[email protected] ~]#
firewall-cmd --add-port={11211/tcp,5672/tcp} --permanent

[[email protected] ~]#
firewall-cmd --reload