teach bitwarden lookup about custom fields

This makes it easier to look up the values of custom fields in a
Bitwarden entry. If the `custom_field` named parameter is true, search
for the named `field` in the list of custom fields rather than the
top-level dictionary.

README.md

@@ -79,6 +79,13 @@ TASK [debug] *********************************************************
 ok: [localhost] => {
     "msg": {
         "favorite": false, 
+        "fields": [
+            {
+                "name": "mycustomfield", 
+                "type": 0, 
+                "value": "the value of my custom field"
+            }
+        ], 
         "folderId": null, 
         "id": "12345678-0123-4321-0000-a97001342c31", 
         "login": {
@@ -96,3 +103,20 @@ ok: [localhost] => {
     }
 }
 ```
+
+### Get the value of a custom field
+
+```yaml
+# Get the value of a custom field
+- debug:
+    msg: {{ lookup('bitwarden', 'Google', field='mycustomfield', custom_field=true }}
+```
+
+The above might result in:
+
+```
+TASK [debug] *********************************************************
+ok: [localhost] => {
+    "msg": "the value of my custom field"
+    }
+```

lookup_plugins/bitwarden.py

@@ -9,6 +9,22 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
+import json
+import os
+import sys
+
+from subprocess import Popen, PIPE, check_output
+
+from ansible.errors import AnsibleError
+from ansible.plugins.lookup import LookupBase
+
+try:
+    from __main__ import display
+except ImportError:
+    from ansible.utils.display import Display
+    display = Display()
+
+
 DOCUMENTATION = """
     lookup: bitwarden
     author:
@@ -26,6 +42,9 @@ DOCUMENTATION = """
       field:
         description: field to return from bitwarden
         default: 'password'
+     custom_field:
+        description: If True, look up named field in custom fields instead
+          of top-level dictionary.
 """
 
 EXAMPLES = """
@@ -40,18 +59,6 @@ RETURN = """
       - Items from Bitwarden vault
 """
 
-from subprocess import Popen, PIPE, check_output
-import os, sys
-
-from ansible.errors import AnsibleError
-from ansible.plugins.lookup import LookupBase
-
-try:
-    from __main__ import display
-except ImportError:
-    from ansible.utils.display import Display
-    display = Display()
-
 
 class Bitwarden(object):
 
@@ -91,6 +98,10 @@ class Bitwarden(object):
     def get_entry(self, key, field):
         return self._run(["get", field, key])
 
+    def get_custom_field(self, key, field):
+        data = json.loads(self.get_entry(key, 'item'))
+        return next(x for x in data['fields'] if x['name'] == field)['value']
+
 
 class LookupModule(LookupBase):
 
@@ -103,6 +114,9 @@ class LookupModule(LookupBase):
         field = kwargs.get('field', 'password')
         values = []
         for term in terms:
+            if kwargs.get('custom_field'):
+                values.append(bw.get_custom_field(term, field))
+            else:
                 values.append(bw.get_entry(term, field))
         return values