Review prerequisites for setting up Ceph nodes in Requirements for Installing Red Hat Ceph Storage. In particular:

Register and subscribe each Ceph node as described in the Registering Red Hat Ceph Storage Nodes. Here is how to subscribe to the necessary repos:

# subscription-manager repos --disable=*
# subscription-manager repos --enable=rhel-7-server-rpms
# subscription-manager repos --enable=rhel-7-server-extras-rpms
# subscription-manager repos --enable=rhel-7-server-rhceph-3-mon-rpms
# subscription-manager repos --enable=rhel-7-server-rhceph-3-osd-rpms
# subscription-manager repos --enable=rhel-7-server-rhceph-3-tools-rpms

Create an ansible user with root privilege on each node. Choose any name you like. For example:

# USER_NAME=ansibleadmin
# useradd $USER_NAME -c "Ansible administrator"
# passwd $USER_NAME
New password: *********
Retype new password: *********
# cat << EOF >/etc/sudoers.d/admin
admin ALL = (root) NOPASSWD:ALL
EOF
# chmod 0440 /etc/sudoers.d/$USER_NAME

In the Ansible user’s home directory create a directory to store temporary values created from the ceph-ansible playbook

# USER_NAME=ansibleadmin
# sudo su - $USER_NAME
[ansibleadmin@ceph05 ~]$ mkdir ~/ceph-ansible-keys

Enable password-less ssh for the ansible user. Run ssh-keygen on ceph05 (leave passphrase empty), then run and repeat ssh-copy-id to copy the public key to the Ansible user on ceph01, ceph02, and ceph03 systems:

# USER_NAME=ansibleadmin
# sudo su - $USER_NAME
[ansibleadmin@ceph05 ~]$ ssh-keygen
[ansibleadmin@ceph05 ~]$ ssh-copy-id $USER_NAME@ceph01
[ansibleadmin@ceph05 ~]$ ssh-copy-id $USER_NAME@ceph02
[ansibleadmin@ceph05 ~]$ ssh-copy-id $USER_NAME@ceph03
[ansibleadmin@ceph05 ~]$ exit
#

Install the ceph-ansible package:

# yum install ceph-ansible

Create a symbolic between these two directories:

# ln -s /usr/share/ceph-ansible/group_vars \
    /etc/ansible/group_vars

Create copies of Ceph sample yml files to modify:

# cd /usr/share/ceph-ansible
# cp group_vars/all.yml.sample group_vars/all.yml
# cp group_vars/osds.yml.sample group_vars/osds.yml
# cp site.yml.sample site.yml

Edit the copied group_vars/all.yml file. See General Ansible Settings in Table 3.1 for details. For example:

ceph_origin: repository
ceph_repository: rhcs
ceph_repository_type: cdn
ceph_rhcs_version: 3
monitor_interface: eth0
public_network: 192.168.122.0/24

Note that your network device and address range may differ.

Edit the copied group_vars/osds.yml file. See the OSD Ansible Settings in Table 3.2 for details. In this example, the second disk device (/dev/sdb) on each OSD node is used for both data and journal storage:

osd_scenario: collocated
devices:
  - /dev/sdb
dmcrypt: true
osd_auto_discovery: false

Edit the /etc/ansible/hosts inventory file to identify the Ceph nodes as Ceph monitor, OSD and manager nodes. In this example, the storage devices are identified on each node as well:

[mons]
ceph01
ceph02
ceph03

[osds]
ceph01 devices="[ '/dev/sdb' ]"
ceph02 devices="[ '/dev/sdb' ]"
ceph03 devices="[ '/dev/sdb' ]"

[mgrs]
ceph01 devices="[ '/dev/sdb' ]"
ceph02 devices="[ '/dev/sdb' ]"
ceph03 devices="[ '/dev/sdb' ]"

Add this line to the /etc/ansible/ansible.cfg file, to save the output from each Ansible playbook run into your Ansible user’s home directory:

retry_files_save_path = ~/

Check that Ansible can reach all the Ceph nodes you configured as your Ansible user:

# USER_NAME=ansibleadmin
# sudo su - $USER_NAME
[ansibleadmin@ceph05 ~]$ ansible all -m ping
ceph01 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
ceph02 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
ceph03 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
[ansibleadmin@ceph05 ~]$

Run the ceph-ansible playbook (as your Ansible user):

[ansibleadmin@ceph05 ~]$ cd /usr/share/ceph-ansible/
[ansibleadmin@ceph05 ~]$ ansible-playbook site.yml

At this point, the Ansible playbook will check your Ceph nodes and configure them for the services you requested. If anything fails, make needed corrections and rerun the command.

Log into one of the three Ceph nodes (ceph01, ceph02, or ceph03) and check the health of the Ceph cluster:

# ceph health
HEALTH_OK

On the same node, verify that monitoring is working using rados:

# ceph osd pool create test 8
# echo 'Hello World!' > hello-world.txt
# rados --pool test put hello-world hello-world.txt
# rados --pool test get hello-world fetch.txt
# cat fetch.txt
Hello World!