Inventory Management

Now let’s suppose that you’ve cloned the Git platform repository template.

Inventory Management

It is now time to declare your various instances in Ansible’s inventory. Simply extend the ansible/inventories/hosts.txt the following way:

##########
# Global #
##########

[kahuna]
kowabunga-kahuna-1 ansible_host=10.0.0.1 ansible_ssh_user=ubuntu

##################
# EU-WEST Region #
##################

[kiwi_eu_west]
kiwi-eu-west-1 ansible_host=10.50.101.2
kiwi-eu-west-2 ansible_host=10.50.101.3

[kaktus_eu_west]
kaktus-eu-west-a-1 ansible_host=10.50.101.11
kaktus-eu-west-a-2 ansible_host=10.50.101.12
kaktus-eu-west-a-3 ansible_host=10.50.101.13

[eu_west:children]
kiwi_eu_west
kaktus_eu_west

################
# Dependencies #
################

[kiwi:children]
kiwi_eu_west

[kaktus:children]
kaktus_eu_west

In this example, we’ve declared our 6 instances (1 global Kahuna, 2 Kiwi and 3 Kaktus from EU-WEST region and their respective associated private IP addresses (used to deploy through SSH).

They respectively belong to various groups, and we’ve also created sub-groups. This is a special Ansible trick which will allow us to inherit variables from group each instance belongs to.

In that regard, considering the example of kaktus-eu-west1, the instance will be assigned variables from possibly various files. You can then safely:

• declare host-specific variables in ansible/host_vars/kaktus-wu-west-1.yml file.
• declare host-specific sensitive variables in ansible/host_vars/kaktus-eu-west-1.sops.yml file.
• declare kaktus_eu_west group-specific variables in ansible/group_vars/kaktus_eu_west/main.yml file.
• declare kaktus_eu_west group-specific sensitive variables in ansible/group_vars/kaktus_eu_west.sops.yml file.
• declare kaktus group-specific variables in ansible/group_vars/kaktus/main.yml file.
• declare kaktus group-specific sensitive variables in ansible/group_vars/kaktus.sops.yml file.
• declare eu_west group-specific variables in ansible/group_vars/kaktus/eu_west.yml file.
• declare eu_west group-specific sensitive variables in ansible/group_vars/eu_west.sops.yml file.
• declare any other global variables in ansible/group_vars/all/main.yml file.
• declare any other global sensitive variables in ansible/group_vars/all.sops.yml file.

This way, instance can inherit variables from its global type (kaktus), its region (eu_west), and a mix of both (kaktus_eu_west).

Note that Ansible variables precedence will apply:

role defaults < all vars < group vars < host vars < role vars

Let’s take the time to also update the ansible/inventories/group_vars/all/main.yml file to update a few settings:

kowabunga_region_domain: "{{ kowabunga_region }}.acme.local"

where acme.local would be your corporate private domain.