Allow finer grained control for dupe YAML keys (#56933)

* Allow finer grained control for dupe YAML keys

  fixes #16903

* expand option to handle errors

* remove clog for previous version of toggle

* added missing parens

* fix typoe

changelogs/fragments/56805-duplicate-dict-key-warnings.yml

@@ -1,3 +0,0 @@
----
-minor_changes:
-  - added config toggle for YAML duplicate dict key warnings

changelogs/fragments/dupe_yaml_key.yml

@@ -0,0 +1,2 @@
+minor_changes:
+    - Allow expanded options for user to control behaviour on duplicate YAML keys.

lib/ansible/config/base.yml

@@ -1253,16 +1253,17 @@ DOCSITE_ROOT_URL:
   ini:
   - {key: docsite_root_url, section: defaults}
   version_added: "2.8"
-DUPLICATE_DICT_KEY_WARNINGS:
-  name: Toggle warnings for duplicate dict keys in YAML
-  default: True
+DUPLICATE_YAML_DICT_KEY:
+  name: Controls ansible behaviour when finding duplicate keys in YAML.
+  default: warn
   description:
     - By default Ansible will issue a warning when a duplicate dict key is encountered in YAML.
     - These warnings can be silenced by adjusting this setting to False.
-  env: [{name: ANSIBLE_DUPLICATE_DICT_KEY_WARNINGS}]
+  env: [{name: ANSIBLE_DUPLICATE_YAML_DICT_KEY}]
   ini:
-  - {key: duplicate_dict_key_warnings, section: defaults}
-  type: boolean
+  - {key: duplicate_dict_key, section: defaults}
+  type: string
+  choices: ['warn', 'error', 'ignore']
   version_added: "2.9"
 ERROR_ON_MISSING_HANDLER:
   name: Missing handler error

lib/ansible/parsing/yaml/constructor.py

@@ -23,7 +23,7 @@ from yaml.constructor import SafeConstructor, ConstructorError
 from yaml.nodes import MappingNode
 
 from ansible import constants as C
-from ansible.module_utils._text import to_bytes
+from ansible.module_utils._text import to_bytes, to_native
 from ansible.parsing.yaml.objects import AnsibleMapping, AnsibleSequence, AnsibleUnicode
 from ansible.parsing.yaml.objects import AnsibleVaultEncryptedUnicode
 from ansible.utils.unsafe_proxy import wrap_var
@@ -71,9 +71,15 @@ class AnsibleConstructor(SafeConstructor):
                                        "found unacceptable key (%s)" % exc, key_node.start_mark)
 
             if key in mapping:
-                if C.DUPLICATE_DICT_KEY_WARNINGS:
-                    display.warning(u'While constructing a mapping from {1}, line {2}, column {3}, found a duplicate dict key ({0}).'
+                msg = (u'While constructing a mapping from {1}, line {2}, column {3}, found a duplicate dict key ({0}).'
                        u' Using last defined value only.'.format(key, *mapping.ansible_pos))
+                if C.DUPLICATE_YAML_DICT_KEY == 'warn':
+                    display.warning(msg)
+                elif C.DUPLICATE_YAML_DICT_KEY == 'error':
+                    raise ConstructorError(to_native(msg))
+                else:
+                    # when 'ignore'
+                    display.debug(msg)
 
             value = self.construct_object(value_node, deep=deep)
             mapping[key] = value