Add toml inventory plugin (#41593)

* First pass at a toml inventory

* Make EXAMPLES yaml

* Remove unnecessary comment

* Small formatting changes

* Add ansible-inventory option to list as TOML

* TOML inventory improvements, to allow a more simple inventory, specifically related to children

* changelog

* Simplify logic

* Dedupe _expand_hostpattern, making it available to all inventory plugins

* Don't make the TOML inventory dependent on the YAML inventory

* Quote IP address values

* Add more TOML examples

* Further cleanups

* Enable the toml inventory to run by default

* Create toml specific dumper

* 2.8

* Clean up imports

* No toml pygments lexer

* Don't raise an exception early when toml isn't present, and move toml to the end, since it requires an external dep

* Require toml>=0.10.0

* Further clean up of empty data

* Don't require toml>=0.10.0, but prefer it, add code for fallback in older versions

* Ensure we actually pass an encoder to toml.dumps

* Simplify recursive data converter

* Appease tests, since we haven't limited controller testing to 2.7+

* Update docstring for convert_yaml_objects_to_native

* remove outdated catching of AttributeError

* We don't need to catch ImportError when import ansible.plugins.inventory.toml

* Add note about what self.dump_funcs.update is doing

* Address some things

* A little extra comment

* Fix toml availability check

* Don't create an intermediate list

* Require toml file extension

* Add metadata

* Remove TOML docs from intro_inventory to prevent people from getting the wrong idea

* It's in defaults, remove note

* core supported, indicate very clearly that this is preview status

lib/ansible/cli/inventory.py

@@ -94,6 +94,8 @@ class InventoryCLI(CLI):
         # graph
         self.parser.add_option("-y", "--yaml", action="store_true", default=False, dest='yaml',
                                help='Use YAML format instead of default JSON, ignored for --graph')
+        self.parser.add_option('--toml', action='store_true', default=False, dest='toml',
+                               help='Use TOML format instead of default JSON, ignored for --graph')
         self.parser.add_option("--vars", action="store_true", default=False, dest='show_vars',
                                help='Add vars to graph display, ignored unless used with --graph')
 
@@ -176,6 +178,8 @@ class InventoryCLI(CLI):
             top = self._get_group('all')
             if self.options.yaml:
                 results = self.yaml_inventory(top)
+            elif self.options.toml:
+                results = self.toml_inventory(top)
             else:
                 results = self.json_inventory(top)
             results = self.dump(results)
@@ -193,6 +197,13 @@ class InventoryCLI(CLI):
             import yaml
             from ansible.parsing.yaml.dumper import AnsibleDumper
             results = yaml.dump(stuff, Dumper=AnsibleDumper, default_flow_style=False)
+        elif self.options.toml:
+            from ansible.plugins.inventory.toml import toml_dumps, HAS_TOML
+            if not HAS_TOML:
+                raise AnsibleError(
+                    'The python "toml" library is required when using the TOML output format'
+                )
+            results = toml_dumps(stuff)
         else:
             import json
             from ansible.parsing.ajson import AnsibleJSONEncoder
@@ -385,3 +396,45 @@ class InventoryCLI(CLI):
             return results
 
         return format_group(top)
+
+    def toml_inventory(self, top):
+        seen = set()
+        has_ungrouped = bool(next(g.hosts for g in top.child_groups if g.name == 'ungrouped'))
+
+        def format_group(group):
+            results = {}
+            results[group.name] = {}
+
+            results[group.name]['children'] = []
+            for subgroup in sorted(group.child_groups, key=attrgetter('name')):
+                if subgroup.name == 'ungrouped' and not has_ungrouped:
+                    continue
+                if group.name != 'all':
+                    results[group.name]['children'].append(subgroup.name)
+                results.update(format_group(subgroup))
+
+            if group.name != 'all':
+                for host in sorted(group.hosts, key=attrgetter('name')):
+                    if host.name not in seen:
+                        seen.add(host.name)
+                        host_vars = self._get_host_variables(host=host)
+                        self._remove_internal(host_vars)
+                    else:
+                        host_vars = {}
+                    try:
+                        results[group.name]['hosts'][host.name] = host_vars
+                    except KeyError:
+                        results[group.name]['hosts'] = {host.name: host_vars}
+
+            if self.options.export:
+                results[group.name]['vars'] = self._get_group_variables(group)
+
+            self._remove_empty(results[group.name])
+            if not results[group.name]:
+                del results[group.name]
+
+            return results
+
+        results = format_group(top)
+
+        return results