From ccef8ebb234f07df1d72755bca9213b778efa6a0 Mon Sep 17 00:00:00 2001
From: Murat Aybars <39916128+aybarsm@users.noreply.github.com>
Date: Fri, 12 Jul 2024 13:24:29 +0100
Subject: [PATCH] Role: new:: hosts (completed & tested)

---
 roles/hosts/defaults/main.yml      | 17 +++++++++++++++++
 roles/hosts/tasks/main.yml         | 11 +++++++++++
 roles/hosts/templates/etc/hosts.j2 | 15 +++++++++++++++
 roles/hosts/vars/main.yml          | 24 ++++++++++++++++++++++++
 4 files changed, 67 insertions(+)
 create mode 100644 roles/hosts/defaults/main.yml
 create mode 100644 roles/hosts/tasks/main.yml
 create mode 100644 roles/hosts/templates/etc/hosts.j2
 create mode 100644 roles/hosts/vars/main.yml

diff --git a/roles/hosts/defaults/main.yml b/roles/hosts/defaults/main.yml
new file mode 100644
index 0000000..e6ff03b
--- /dev/null
+++ b/roles/hosts/defaults/main.yml
@@ -0,0 +1,17 @@
+hosts__role_enabled: false
+
+hosts__dir: /etc
+hosts__file: "{{ hosts__dir }}/hosts"
+hosts__template: etc/hosts.j2
+hosts__backup: true
+
+# If enabled, the ansible inventory will be collected automatically
+# and will be appended to the list of hosts, when ansible_host (ip address) is defined.
+# ip: ansible_host, hostname: inventory_hostname_short, fqdn: inventory_hostname
+hosts__auto_discovery: false
+# Consult https://docs.ansible.com/ansible/latest/inventory_guide/intro_patterns.html for more information
+hosts__auto_discovery_inventories: 'webservers:&atlanta'
+
+hosts__default: []
+hosts__group: []
+hosts__host: []
\ No newline at end of file
diff --git a/roles/hosts/tasks/main.yml b/roles/hosts/tasks/main.yml
new file mode 100644
index 0000000..6a2b787
--- /dev/null
+++ b/roles/hosts/tasks/main.yml
@@ -0,0 +1,11 @@
+---
+- name: Apply hosts configuration
+  become: true
+  ansible.builtin.template:
+    src: "{{ hosts__template }}"
+    dest: "{{ hosts__file }}"
+    backup: "{{ hosts__backup | default(omit) | bool }}"
+  when:
+    - hosts__role_enabled | default(false) | bool
+    - (hosts__all_ipv4 | default([]) | length > 0) or (hosts__all_ipv6 | default([]) | length > 0)
+  register: hosts__apply
diff --git a/roles/hosts/templates/etc/hosts.j2 b/roles/hosts/templates/etc/hosts.j2
new file mode 100644
index 0000000..f7b03ec
--- /dev/null
+++ b/roles/hosts/templates/etc/hosts.j2
@@ -0,0 +1,15 @@
+127.0.0.1 localhost.localdomain localhost
+{% for ipv4_host in hosts__all_ipv4 %}
+{{ ipv4_host.ip }} {{ ipv4_host.fqdn }} {{ ipv4_host.hostname }}
+{% endfor %}
+
+# The following lines are desirable for IPv6 capable hosts
+::1     ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
+{% for ipv6_host in hosts__all_ipv6 %}
+{{ ipv6_host.ip }} {{ ipv6_host.fqdn }} {{ ipv6_host.hostname }}
+{% endfor %}
\ No newline at end of file
diff --git a/roles/hosts/vars/main.yml b/roles/hosts/vars/main.yml
new file mode 100644
index 0000000..a8e14e4
--- /dev/null
+++ b/roles/hosts/vars/main.yml
@@ -0,0 +1,24 @@
+
+__hosts__auto_discovered: >-
+  {%- if (hosts__auto_discovery | default(false) | bool) and hosts__auto_discovery_inventories is defined and hosts__auto_discovery_inventories | length > 0 -%}
+  {%- set inventory_lookup = lookup('ansible.builtin.inventory_hostnames', hosts__auto_discovery_inventories) -%}
+  {%-   if inventory_lookup | length > 0 -%}
+  {%-     set inventory_hosts = inventory_lookup | split(',') -%}
+  {%-     set discovered_hosts = dict(hostvars) | aybarsm.helper.only_with(inventory_hosts) | dict2items | selectattr('value.ansible_host', 'defined') -%}
+  {%-     set ips = discovered_hosts | map(attribute='value.ansible_host') -%}
+  {%-     set hostnames = discovered_hosts | map(attribute='value.inventory_hostname_short') -%}
+  {%-     set fqdns = discovered_hosts | map(attribute='value.inventory_hostname') -%}
+  {%-     set auto_discovered = {'ip': ips, 'hostname': hostnames, 'fqdn': fqdns} | aybarsm.helper.to_list_of_dicts -%}
+  {%-   endif -%}
+  {%- else -%}
+  {%- set auto_discovered = [] -%}
+  {%- endif -%}
+  {{ auto_discovered }}
+
+hosts__all: "{{ (hosts__host + hosts__group + hosts__default + __hosts__auto_discovered) |
+  aybarsm.helper.replace_aliases({'fqdn': ['hostname']}) |
+  aybarsm.helper.selectattr([{'when': [['ip', 'defined'], ['hostname', 'defined'], ['fqdn', 'defined']]}]) |
+  aybarsm.helper.unique_recursive(['ip', 'hostname', 'fqdn']) | default([]) }}"
+
+hosts__all_ipv4: "{{ hosts__all | selectattr('ip', 'ansible.utils.ipv4') }}"
+hosts__all_ipv6: "{{ hosts__all | selectattr('ip', 'ansible.utils.ipv6') }}"
\ No newline at end of file