template module - render `None` as empty string (#85121)

* template module - render `None` as empty string

* Update changelogs/fragments/template-none.yml

Co-authored-by: Matt Davis <6775756+nitzmahone@users.noreply.github.com>

---------

Co-authored-by: Matt Davis <6775756+nitzmahone@users.noreply.github.com>
(cherry picked from commit 4fe9606530)

changelogs/fragments/template-none.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - template action - Template files where the entire file's output renders as ``None`` are no longer emitted as the string "None", but instead render to an empty file as in previous releases.

lib/ansible/plugins/action/template.py

@@ -132,6 +132,9 @@ class ActionModule(ActionBase):
             data_templar = self._templar.copy_with_new_env(searchpath=searchpath, available_variables=temp_vars)
             resultant = data_templar.template(template_data, escape_backslashes=False, overrides=overrides)
 
+            if resultant is None:
+                resultant = ''
+
             new_task = self._task.copy()
             # mode is either the mode from task.args or the mode of the source file if the task.args
             # mode == 'preserve'

test/integration/targets/lookup_template/tasks/main.yml

@@ -32,3 +32,7 @@
       - lookup('template', 'dict.j2') is not mapping
 
 - include_tasks: trim_blocks.yml
+
+- name: Verify templates with no rendered content return `None`
+  assert:
+    that: "{{ lookup('template', 'none.j2') is none }}"

test/integration/targets/lookup_template/templates/none.j2

@@ -0,0 +1 @@
+{# a template with no content will render as `None` #}

test/integration/targets/template/tasks/main.yml

@@ -19,6 +19,15 @@
 - set_fact:
     output_dir: "{{ lookup('env', 'OUTPUT_DIR') }}"
 
+- name: render a template which has no content
+  template:
+    src: none.j2
+    dest: '{{ output_dir }}/none.templated'
+
+- name: verify a template with no content renders as an empty string
+  assert:
+    that: "{{ lookup('file', output_dir ~ '/none.templated') == '' }}"
+
 - name: get default group
   shell: id -gn
   register: group

test/integration/targets/template/templates/none.j2

@@ -0,0 +1 @@
+{# a template with no content will render as `None` #}