config lookup plugin (#32392)

* config lookup plugin

* added info about ansible-config list

* fixed typoes

* now with option and error handling

* fixed import, better docs

lib/ansible/plugins/lookup/config.py

@@ -0,0 +1,85 @@
+# (c) 2017 Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+DOCUMENTATION = """
+    lookup: config
+    author: Ansible Core
+    version_added: "2.5"
+    short_description: Lookup current Ansilbe configuration values
+    description:
+      - Retrieves the value of an Ansible configuration setting.
+      - You can use ``ansible-config list`` to see all available settings.
+    options:
+      _terms:
+        description: The key(s) to look up
+        required: True
+      on_missing:
+        description:
+            - action to take if term is missing from config
+            - Error will raise a fatal error
+            - Skip will just ignore the term
+            - Warn will skip over it but issue a warning
+        default: error
+        type: string
+        choices: ['error', 'skip', 'warn']
+"""
+
+EXAMPLES = """
+    - name: Show configured default become user
+      debug: msg="{{ lookup('config', 'DEFAULT_BECOME_USER')}}"
+
+    - name: print out role paths
+      debug: msg="These are the configured role paths: {{lookup('config', 'DEFAULT_ROLES_PATH')}}"
+
+    - name: find retry files, skip if missing that key
+      find:
+        paths: "{{lookup('config', 'RETRY_FILES_SAVE_PATH')|default(playbook_dir, True)}}"
+        patterns: "*.retry"
+
+    - name: see the colors
+      debug: msg="{{item}}"
+      loop: "{{lookup('config', 'COLOR_OK', 'COLOR_CHANGED', 'COLOR_SKIP', wantlist=True)}}"
+
+    - name: skip if bad value in var
+      debug: msg="{{ lookup('config', config_in_var, on_missing='skip')}}"
+      var:
+        config_in_var: UNKNOWN
+"""
+
+RETURN = """
+_raw:
+  description:
+    - value(s) of the key(s) in the config
+"""
+
+from ansible import constants as C
+from ansible.errors import AnsibleError
+from ansible.module_utils.six import string_types
+from ansible.plugins.lookup import LookupBase
+
+
+class LookupModule(LookupBase):
+
+    def run(self, terms, variables=None, **kwargs):
+
+        missing = kwargs.get('on_missing', 'error').lower()
+        if not isinstance(missing, string_types) or missing not in ['error', 'warn', 'skip']:
+            raise AnsibleError('"on_missing" must be a string and one of "error", "warn" or "skip", not %s' % missing)
+
+        ret = []
+        for term in terms:
+            if not isinstance(term, string_types):
+                raise AnsibleError('Invalid setting identifier, "%s" is not a string, its a %s' % (term, type(term)))
+            try:
+                result = getattr(C, term)
+                if callable(result):
+                    raise AnsibleError('Invalid setting "%s" attempted' % term)
+                ret.append(result)
+            except AttributeError:
+                if missing == 'error':
+                    raise AnsibleError('Unable to find setting %s' % term)
+                elif missing == 'warn':
+                    self._display.warning('Skipping, did not find setting %s' % term)
+        return ret