I continue to expressively retell Ansible's documentation and analyze the consequences of not knowing it (link to the previous part) .

In this part, we discuss inventories. I also promised variables, but inventory turned out to be a big topic, so we devote a separate article to it.

We will analyze each element of the inventory (except host_group_vars plugin) and discuss why it is, how to use it correctly, and how it is wrong.

Table of contents:

• What is a Host? (and a little about transports)
• IP vs FQDN access; inventory_hostnamevsansible_host
• ansible_user - to write or not to write?
• Groups
• Variables: Inventory or Playbook?
• Classification of inventories by origin.

Inventory is a list of hosts, groups, as well as auxiliary variables. Studying the basics, we will analyze each moment in detail, with a search for how "should" and condemnation of "how not".

Inventory: hosts

The host in the inventory is the elements of the dictionary hostsfor the group in the yaml-inventory (in the ini-inventory, this is the first element of the line):

    somegroup:
        hosts:
           somehost1:
           somehost2:

somehost1, somehost2 are hosts.

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:

---
somegroup:
  hosts:
     somehost:
         ansible_host: 254.12.11.10

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    - name: Ping neighbor
      command: ping -c 1 {{ neighbor_ip }} -w 1
      changed_when: false
      vars:
        neighbor_ip: '{{ (hostvars[item].ansible_all_ipv4_addresses|ipaddr(public_network))[0] }}'
      with_items: '{{ groups[target_group] }}'

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---
foo:
   hosts:
      foo1:
      foo2:

bar:
  hosts:
      bar1

foobar:
  children:
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     bar:

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.

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.

ansible-playbook -i inventory1.yaml -i inventory2.yaml play.yaml

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---

:

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