plugin_filter: check for type error (ansible#46664)

* Parsing plugin filter may raise TypeError, gracefully handle this exception
and let user know about the syntax error in plugin filter file.

* Test for plugin_filtering

Fixes: ansible#46658

Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>
(cherry picked from commit b32b411)

changelogs/fragments/46658-plugin_filter-improve_error_handling.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+- Parsing plugin filter may raise TypeError, gracefully handle this exception and let user know about the syntax error in plugin filter file.

lib/ansible/plugins/loader.py

@@ -574,10 +574,9 @@ def all(self, *args, **kwargs):
 
 def _load_plugin_filter():
     filters = defaultdict(frozenset)
-
+    user_set = False
     if C.PLUGIN_FILTERS_CFG is None:
         filter_cfg = '/etc/ansible/plugin_filters.yml'
-        user_set = False
     else:
         filter_cfg = C.PLUGIN_FILTERS_CFG
         user_set = True
@@ -605,11 +604,17 @@ def _load_plugin_filter():
         if version == u'1.0':
             # Modules and action plugins share the same blacklist since the difference between the
             # two isn't visible to the users
-            filters['ansible.modules'] = frozenset(filter_data['module_blacklist'])
+            try:
+                filters['ansible.modules'] = frozenset(filter_data['module_blacklist'])
+            except TypeError:
+                display.warning(u'Unable to parse the plugin filter file {0} as'
+                                u' module_blacklist is not a list.'
+                                u' Skipping.'.format(filter_cfg))
+                return filters
             filters['ansible.plugins.action'] = filters['ansible.modules']
         else:
             display.warning(u'The plugin filter file, {0} was a version not recognized by this'
-                            u' version of Ansible. Skipping.')
+                            u' version of Ansible. Skipping.'.format(filter_cfg))
     else:
         if user_set:
             display.warning(u'The plugin filter file, {0} does not exist.'

test/integration/targets/plugin_filtering/no_blacklist_module.ini

@@ -0,0 +1,3 @@
+[defaults]
+retry_files_enabled = False
+plugin_filters_cfg = ./no_blacklist_module.yml

test/integration/targets/plugin_filtering/no_blacklist_module.yml

@@ -0,0 +1,3 @@
+---
+filter_version: 1.0
+module_blacklist:

test/integration/targets/plugin_filtering/runme.sh

@@ -21,6 +21,15 @@ if test $? != 0 ; then
 	exit 1
 fi
 
+#
+# Check that if no modules are blacklisted then Ansible should not through traceback
+#
+ANSIBLE_CONFIG=no_blacklist_module.ini ansible-playbook tempfile.yml  -i ../../inventory -vvv "$@"
+if test $? != 0 ; then
+	echo "### Failed to run tempfile with no modules blacklisted"
+	exit 1
+fi
+
 #
 # Check that with these modules filtered out, all of these modules fail to be found
 #