add toggle for host pattern mismatch behaviour (#51199)

* add toggle for host pattern mismatch behaviour

	fixes #40030

* fix

lib/ansible/config/base.yml

@@ -1391,6 +1391,15 @@ HOST_KEY_CHECKING:
   ini:
   - {key: host_key_checking, section: defaults}
   type: boolean
+HOST_PATTERN_MISMATCH:
+  name: Control host pattern mismatch behaviour
+  default: 'warning'
+  description: This setting changes the behaviour of mismatched host patterns, it allows you to force a fatal error, a warning or just ignore it
+  env: [{name: ANSIBLE_HOST_PATTERN_MISMATCH}]
+  ini:
+  - {key: host_pattern_mismatch, section: inventory}
+  choices: ['warning', 'error', 'ignore']
+  version_added: "2.8"
 INVALID_TASK_ATTRIBUTE_FAILED:
   name: Controls whether invalid attributes for a task result in errors instead of warnings
   default: True

lib/ansible/inventory/manager.py

@@ -553,7 +553,13 @@ class InventoryManager(object):
 
         # Display warning if specified host pattern did not match any groups or hosts
         if not results and not matching_groups and pattern != 'all':
-            display.warning("Could not match supplied host pattern, ignoring: %s" % pattern)
+            msg = "Could not match supplied host pattern, ignoring: %s" % pattern
+            display.debug(msg)
+            if C.HOST_PATTERN_MISMATCH == 'warning':
+                display.warning(msg)
+            elif C.HOST_PATTERN_MISMATCH == 'error':
+                raise AnsibleOptionsError(msg)
+            # no need to write 'ignore' state
 
         return results