Ansible lookup plugin for os dependent variable loading

variable_loader.py

DOCUMENTATION = """
    lookup: variable_loader
    author: Dominik Rimpf <dev@drimpf.de>
    short_description: tries to find variable files dependent on node operating system
    description:
      - this lookup checks for files in 'role_path/vars/' and returns the full path to the first combination found.
    notes:
      - If no arguments are passed following default list is used:
        - "{{ ansible_distribution }}_{{ ansible_distribution_major_version }}.yml"
        - "{{ ansible_distribution }}.yml"
        - "{{ ansible_os_family }}_{{ ansible_distribution_major_version }}.yml"
        - "{{ ansible_os_family }}.yml"
      - File names can be passed seperately as strings or in a list. (Or both mixed)
    options:
      _terms:
        description: list of file names (or file name)
      files:
        description: list of file names
"""

EXAMPLES = """
- name: read vars form os-dependent variable file
  include_vars: "{{ lookup('variable_loader') }}"

- name: read vars from first found given variable file in role_path
  include_vars: "{{ lookup('first_found', params) }}"
  vars:
    params:
      - '{{ ansible_os_distribution }}.yml'
      - '{{ ansible_os_family }}.yml'
      - default.yml
"""

RETURN = """
  _raw:
    description:
      - path to file found
"""


import os

from jinja2.exceptions import UndefinedError

from ansible.errors import AnsibleFileNotFound, AnsibleLookupError, AnsibleUndefinedVariable
from ansible.module_utils.six import string_types
from ansible.plugins.lookup import LookupBase

class LookupModule(LookupBase):

    def run(self, terms, variables, **kwargs):
        # Variablen aus dem Dict holen
        search_path = os.path.join(variables["role_path"], "vars")
        ansible_distribution = variables["ansible_distribution"]
        ansible_distribution_major_version = variables["ansible_distribution_major_version"]
        ansible_os_family = variables["ansible_os_family"]
        
        # Dateinamen nach denen gesucht werden soll
        if terms == []:
          filenames = [
            f"{ansible_distribution}_{ansible_distribution_major_version}.yml",
            f"{ansible_distribution}.yml",
            f"{ansible_os_family}_{ansible_distribution_major_version}.yml", # Macht der Eintrag überhaupt Sinn? bei Ubuntu 18.04 würde das "Debian_18" rauskommen, das ist doch nicht Sinn der Sache?
            f"{ansible_os_family}.yml"
          ]
        else:
          filenames = []
          for term in self._flatten(terms):
            if isinstance(term, string_types):
              filenames.append(term)
            else:
              raise AnsibleLookupError("Only strings or lists of strings are allowed as arguments")

        self._display.vv(f"Searching for files {filenames} in {search_path}.")

        total_search = []
        for fn in filenames:
            f = os.path.join(search_path, fn)
            total_search.append(f)

        for fn in total_search:
            path = None
            path = self.find_file_in_search_path(variables, 'vars', fn, ignore_missing=True)
            if path is not None:
                self._display.vvv(f"Found {fn} at {path}")
                return [path]
            else:
                self._display.vvvv(f"Did not find {fn}.")

        raise AnsibleLookupError("No file was found. Use errors='ignore' to allow this task to be skipped if no files are found")