Add a named parameter to the filter to_uuid (#64057)

Let the caller choose a namespace for `to_uuid` and document the
behaviour of both the default case, and the new explicit case.

This PR does not change the existing behaviour of the `to_uuid` UUIDv5
filter.

changelogs/fragments/64057-Add_named_parameter_to_the_to_uuid_filter.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+  - to_uuid - add a named parameter to let the user optionally set a custom namespace

docs/docsite/rst/user_guide/playbooks_filters.rst

@@ -1279,9 +1279,17 @@ As of version 2.6, you can define the type of encoding to use, the default is ``
 
 .. versionadded:: 2.6
 
-To create a UUID from a string (new in version 1.9)::
+To create a namespaced UUIDv5::
 
-    {{ hostname | to_uuid }}
+    {{ string | to_uuid(namespace='11111111-2222-3333-4444-555555555555') }}
+
+.. versionadded:: 2.10
+
+To create a namespaced UUIDv5 using the default Ansible namespace '361E6D51-FAEC-444A-9079-341386DA8E2E'::
+
+    {{ string | to_uuid }}
+
+.. versionadded:: 1.9
 
 To cast values as certain types, such as when you input a string as "True" from a vars_prompt and the system
 doesn't know it is a boolean value::

lib/ansible/plugins/filter/core.py

@@ -276,8 +276,15 @@ def get_encrypted_password(password, hashtype='sha512', salt=None, salt_size=Non
         reraise(AnsibleFilterError, AnsibleFilterError(to_native(e), orig_exc=e), sys.exc_info()[2])
 
 
-def to_uuid(string):
+def to_uuid(string, namespace=UUID_NAMESPACE_ANSIBLE):
-    return str(uuid.uuid5(UUID_NAMESPACE_ANSIBLE, str(string)))
+    uuid_namespace = namespace
+    if not isinstance(uuid_namespace, uuid.UUID):
+        try:
+            uuid_namespace = uuid.UUID(namespace)
+        except (AttributeError, ValueError) as e:
+            raise AnsibleFilterError("Invalid value '%s' for 'namespace': %s" % (to_native(namespace), to_native(e)))
+    # uuid.uuid5() requires bytes on Python 2 and bytes or text or Python 3
+    return to_text(uuid.uuid5(uuid_namespace, to_native(string, errors='surrogate_or_strict')))
 
 
 def mandatory(a, msg=None):

test/units/plugins/filter/test_uuid.py

@@ -0,0 +1,41 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2019 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
+
+import pytest
+
+from ansible.module_utils._text import to_native
+from ansible.plugins.filter.core import to_uuid
+from ansible.errors import AnsibleFilterError
+
+
+UUID_DEFAULT_NAMESPACE_TEST_CASES = (
+    ('example.com', 'ae780c3a-a3ab-53c2-bfb4-098da300b3fe'),
+    ('test.example', '8e437a35-c7c5-50ea-867c-5c254848dbc2'),
+    ('café.example', '8a99d6b1-fb8f-5f78-af86-879768589f56'),
+)
+
+UUID_TEST_CASES = (
+    ('361E6D51-FAEC-444A-9079-341386DA8E2E', 'example.com', 'ae780c3a-a3ab-53c2-bfb4-098da300b3fe'),
+    ('361E6D51-FAEC-444A-9079-341386DA8E2E', 'test.example', '8e437a35-c7c5-50ea-867c-5c254848dbc2'),
+    ('11111111-2222-3333-4444-555555555555', 'example.com', 'e776faa5-5299-55dc-9057-7a00e6be2364'),
+)
+
+
+@pytest.mark.parametrize('value, expected', UUID_DEFAULT_NAMESPACE_TEST_CASES)
+def test_to_uuid_default_namespace(value, expected):
+    assert expected == to_uuid(value)
+
+
+@pytest.mark.parametrize('namespace, value, expected', UUID_TEST_CASES)
+def test_to_uuid(namespace, value, expected):
+    assert expected == to_uuid(value, namespace=namespace)
+
+
+def test_to_uuid_invalid_namespace():
+    with pytest.raises(AnsibleFilterError) as e:
+        to_uuid('example.com', namespace='11111111-2222-3333-4444-555555555')
+    assert 'Invalid value' in to_native(e.value)