Introduce inventory.any_unparsed_is_failed configuration setting (#41171)

In the process of building up the inventory by parsing each inventory
source with each available inventory plugin, there are three kinds of
possible errors (listed in order from earliest to latest):

1. One source could not be parsed by a particular plugin.
2. One source could not be parsed by any available plugin.
3. ALL sources could not be parsed by any available plugin.

The errors in (1) are a part of normal operation, e.g., the script
plugin is expected to fail to parse an ini-format source, and we will
ignore that error and try the next plugin. There is currently no way to
control this, and no known compelling use-case for a setting to control
it. This commit does not make any changes here.

We implement "any_unparsed_is_failed" to handle (2) above. If enabled,
this requires that every available source be parsed validly by at least
one plugin. In an inventory comprising a static hosts file and ec2.py,
this setting will cause a fatal error if ec2.py fails (a situation that
attracted only a warning earlier).

We clarify that the existing "unparsed_is_failed=true" setting causes a
fatal error only in (3) above, i.e., if NO inventory source could be
parsed. In other words, if there is ANY valid source in the inventory
(e.g., an ini-format static file), no combination of errors and the
setting will cause a fatal error.

If you want to execute your playbooks when your inventory is…

    (a) complete, use "any_unparsed_is_failed=true".
    (b) not empty, use "unparsed_is_failed=true".

The "unparsed_is_failed" setting should be renamed to
"all_unparsed_is_failed", but this commit does not do so.

Fixes #40512
Fixes #40996

changelogs/fragments/any_unparsed_is_failed.yaml

@@ -0,0 +1,5 @@
+---
+minor_changes:
+  - Added inventory.any_unparsed_is_failed configuration setting. In an
+    inventory with a static hosts file and (say) ec2.py, enabling this
+    setting will cause a failure instead of a warning if ec2.py fails.

lib/ansible/config/base.yml

@@ -1375,6 +1375,18 @@ HOST_KEY_CHECKING:
   ini:
   - {key: host_key_checking, section: defaults}
   type: boolean
+INVENTORY_ANY_UNPARSED_IS_FAILED:
+  name: Controls whether any unparseable inventory source is a fatal error
+  default: False
+  description: >
+    If 'true', it is a fatal error when any given inventory source
+    cannot be successfully parsed by any available inventory plugin;
+    otherwise, this situation only attracts a warning.
+  type: boolean
+  env: [{name: ANSIBLE_INVENTORY_ANY_UNPARSED_IS_FAILED}]
+  ini:
+    - {key: any_unparsed_is_failed, section: inventory}
+  version_added: "2.7"
 INVENTORY_ENABLED:
   name: Active Inventory plugins
   default: ['host_list', 'script', 'yaml', 'ini', 'auto']
@@ -1412,7 +1424,10 @@ INVENTORY_IGNORE_PATTERNS:
 INVENTORY_UNPARSED_IS_FAILED:
   name: Unparsed Inventory failure
   default: False
-  description: If 'true' unparsed inventory sources become fatal errors, they are warnings otherwise.
+  description: >
+    If 'true' it is a fatal error if every single potential inventory
+    source fails to parse, otherwise this situation will only attract a
+    warning.
   env: [{name: ANSIBLE_INVENTORY_UNPARSED_FAILED}]
   ini:
   - {key: unparsed_is_failed, section: inventory}

lib/ansible/inventory/manager.py

@@ -285,6 +285,8 @@ class InventoryManager(object):
                         display.warning(u'\n* Failed to parse %s with %s plugin: %s' % (to_text(fail['src']), fail['plugin'], to_text(fail['exc'])))
                         if hasattr(fail['exc'], 'tb'):
                             display.vvv(to_text(fail['exc'].tb))
+                    if C.INVENTORY_ANY_UNPARSED_IS_FAILED:
+                        raise AnsibleError(u'Completely failed to parse inventory source %s' % (to_text(source)))
         if not parsed:
             display.warning("Unable to parse %s as an inventory source" % to_text(source))