Make hostvars json/yaml serializable in filters

Fixes #12615

lib/ansible/parsing/yaml/dumper.py

@@ -23,6 +23,7 @@ import yaml
 from ansible.compat.six import PY3
 
 from ansible.parsing.yaml.objects import AnsibleUnicode
+from ansible.vars.hostvars import HostVars
 
 class AnsibleDumper(yaml.SafeDumper):
     '''
@@ -31,6 +32,9 @@ class AnsibleDumper(yaml.SafeDumper):
     '''
     pass
 
+def represent_hostvars(self, data):
+    return self.represent_dict(dict(data))
+
 if PY3:
     represent_unicode = yaml.representer.SafeRepresenter.represent_str
 else:
@@ -41,3 +45,8 @@ AnsibleDumper.add_representer(
     represent_unicode,
 )
 
+AnsibleDumper.add_representer(
+    HostVars,
+    represent_hostvars,
+)
+

lib/ansible/plugins/filter/core.py

@@ -45,6 +45,7 @@ from ansible.parsing.yaml.dumper import AnsibleDumper
 from ansible.utils.hashing import md5s, checksum_s
 from ansible.utils.unicode import unicode_wrap, to_unicode
 from ansible.utils.vars import merge_hash
+from ansible.vars.hostvars import HostVars
 
 try:
     import passlib.hash
@@ -55,6 +56,17 @@ except:
 
 UUID_NAMESPACE_ANSIBLE = uuid.UUID('361E6D51-FAEC-444A-9079-341386DA8E2E')
 
+class AnsibleJSONEncoder(json.JSONEncoder):
+    '''
+    Simple encoder class to deal with JSON encoding of internal
+    types like HostVars
+    '''
+    def default(self, o):
+        if isinstance(o, HostVars):
+            return dict(o)
+        else:
+            return o
+
 def to_yaml(a, *args, **kw):
     '''Make verbose, human readable yaml'''
     transformed = yaml.dump(a, Dumper=AnsibleDumper, allow_unicode=True, **kw)
@@ -67,7 +79,7 @@ def to_nice_yaml(a, *args, **kw):
 
 def to_json(a, *args, **kw):
     ''' Convert the value to JSON '''
-    return json.dumps(a, *args, **kw)
+    return json.dumps(a, cls=AnsibleJSONEncoder, *args, **kw)
 
 def to_nice_json(a, *args, **kw):
     '''Make verbose, human readable JSON'''
@@ -87,7 +99,7 @@ def to_nice_json(a, *args, **kw):
                     return simplejson.dumps(a, indent=4, sort_keys=True, *args, **kw)
         # Fallback to the to_json filter
         return to_json(a, *args, **kw)
-    return json.dumps(a, indent=4, sort_keys=True, *args, **kw)
+    return json.dumps(a, indent=4, sort_keys=True, cls=AnsibleJSONEncoder, *args, **kw)
 
 def bool(a):
     ''' return a bool for the arg '''

lib/ansible/vars/hostvars.py

@@ -78,10 +78,11 @@ class HostVars(collections.Mapping):
         return False
 
     def __iter__(self):
-        raise NotImplementedError('HostVars does not support iteration as hosts are discovered on an as needed basis.')
+        for host in self._lookup:
+            yield host
 
     def __len__(self):
-        raise NotImplementedError('HostVars does not support len.  hosts entries are discovered dynamically as needed')
+        return len(self._lookup)
 
     def __getstate__(self):
         return dict(loader=self._loader, lookup=self._lookup, play=self._play, var_manager=self._variable_manager)