An ansible role to demo setting and using custom facts

role-custom-facts-demo.yml

---
# Ansible role to show creating and using custom facts.
# https://docs.ansible.com/ansible/latest/modules/setup_module.html
#
# ansible-playbook --connection=local -i "127.0.0.1," role-custom-facts-demo.yml

- name: Ansible custom facts
  hosts: all
  gather_facts: no

  vars:
    somevar: "foobar"

  tasks:

    - name: create fact
      block:

        - name: make facts dir
          file:
            path: /etc/ansible/facts.d/
            state: directory
          become: true

        - name: create script
          copy:
            dest: "/etc/ansible/facts.d/customtest.fact"
            mode: 0755
            owner: root
            group: root
            content: |
              #!/usr/bin/env python3
              # example of ansible custom fact script
              import os
              import sys
              import platform
              import datetime
              import json
              # var:
              date = str(datetime.datetime.now())
              # get hostname
              host_file = open("/etc/hostname")
              bid_line = host_file.read().replace("\n", "")
              host_file.close()
              # output
              print(json.dumps({
                  "time" : date,
                  "host_id" : bid_line
              }))
          become: true


    - name: use the new fact
      block:
        - name: refresh ansible facts
          setup: ~

        - name: check custom fact was set
          assert:
            that:
              - ansible_local.customtest.host_id is defined

        - name: display time from custom fact
          debug:
            msg: "customtest time var {{ ansible_local.customtest.time }}"