Configure Tower in Tower:

* Add separate Django app for configuration: awx.conf.
* Migrate from existing main.TowerSettings model to conf.Setting.
* Add settings wrapper to allow get/set/del via django.conf.settings.
* Update existing references to tower_settings to use django.conf.settings.
* Add a settings registry to allow for each Django app to register configurable settings.
* Support setting validation and conversion using Django REST Framework fields.
* Add /api/v1/settings/ to display a list of setting categories.
* Add /api/v1/settings/<slug>/ to display all settings in a category as a single object.
* Allow PUT/PATCH to update setting singleton, DELETE to reset to defaults.
* Add "all" category to display all settings across categories.
* Add "changed" category to display only settings configured in the database.
* Support per-user settings via "user" category (/api/v1/settings/user/).
* Support defaults for user settings via "user-defaults" category (/api/v1/settings/user-defaults/).
* Update serializer metadata to support category, category_slug and placeholder on OPTIONS responses.
* Update serializer metadata to handle child fields of a list/dict.
* Hide raw data form in browsable API for OPTIONS and DELETE.
* Combine existing licensing code into single "TaskEnhancer" class.
* Move license helper functions from awx.api.license into awx.conf.license.
* Update /api/v1/config/ to read/verify/update license using TaskEnhancer and settings wrapper.
* Add support for caching settings accessed via settings wrapper.
* Invalidate cached settings when Setting model changes or is deleted.
* Preload all database settings into cache on first access via settings wrapper.
* Add support for read-only settings than can update their value depending on other settings.
* Use setting_changed signal whenever a setting changes.
* Register configurable authentication, jobs, system and ui settings.
* Register configurable LDAP, RADIUS and social auth settings.
* Add custom fields and validators for URL, LDAP, RADIUS and social auth settings.
* Rewrite existing validator for Credential ssh_private_key to support validating private keys, certs or combinations of both.
* Get all unit/functional tests working with above changes.
* Add "migrate_to_database_settings" command to determine settings to be migrated into the database and comment them out when set in Python settings files.
* Add support for migrating license key from file to database.
* Remove database-configuable settings from local_settings.py example files.
* Update setup role to no longer install files for database-configurable settings.

f 94ff6ee More settings work.
f af4c4e0 Even more db settings stuff.
f 96ea9c0 More settings, attempt at singleton serializer for settings.
f 937c760 More work on singleton/category views in API, add code to comment out settings in Python files, work on command to migrate settings to database.
f 425b0d3 Minor fixes for sprint demo.
f ea402a4 Add support for read-only settings, cleanup license engine, get license support working with DB settings.
f ec289e4 Rename migration, minor fixmes, update setup role.
f 603640b Rewrite key/cert validator, finish adding social auth fields, hook up signals for setting_changed, use None to imply a setting is not set.
f 67d1b5a Get functional/unit tests passing.
f 2919b62 Flake8 fixes.
f e62f421 Add redbaron to requirements, get file to database migration working (except for license).
f c564508 Add support for migrating license file.
f 982f767 Add support for regex in social map fields.

awx/conf/serializers.py

@@ -0,0 +1,79 @@
+# Django REST Framework
+from rest_framework import serializers
+
+# Tower
+from awx.api.fields import VerbatimField
+from awx.api.serializers import BaseSerializer
+from awx.conf.models import Setting
+from awx.conf import settings_registry
+
+
+class SettingSerializer(BaseSerializer):
+    """Read-only serializer for activity stream."""
+
+    value = VerbatimField(allow_null=True)
+
+    class Meta:
+        model = Setting
+        fields = ('id', 'key', 'value')
+        readonly_fields = ('id', 'key', 'value')
+
+    def __init__(self, instance=None, data=serializers.empty, **kwargs):
+        if instance is None and data is not serializers.empty and 'key' in data:
+            try:
+                instance = Setting.objects.get(key=data['key'])
+            except Setting.DoesNotExist:
+                pass
+        super(SettingSerializer, self).__init__(instance, data, **kwargs)
+
+
+class SettingCategorySerializer(serializers.Serializer):
+    """Serialize setting category """
+
+    url = serializers.CharField(
+        read_only=True,
+    )
+    slug = serializers.CharField(
+        read_only=True,
+    )
+    name = serializers.CharField(
+        read_only=True,
+    )
+
+
+class SettingFieldMixin(object):
+    """Mixin to use a registered setting field class for API display/validation."""
+
+    def to_representation(self, obj):
+        return obj
+
+    def to_internal_value(self, value):
+        obj = super(SettingFieldMixin, self).to_internal_value(value)
+        return super(SettingFieldMixin, self).to_representation(obj)
+
+
+class SettingSingletonSerializer(serializers.Serializer):
+    """Present a group of settings (by category) as a single object."""
+
+    def __init__(self, instance=None, data=serializers.empty, **kwargs):
+        # Instance (if given) should be an object with attributes for all of the
+        # settings in the category; never an actual Setting model instance.
+        assert instance is None or not hasattr(instance, 'pk')
+        super(SettingSingletonSerializer, self).__init__(instance, data, **kwargs)
+
+    def get_fields(self):
+        fields = super(SettingSingletonSerializer, self).get_fields()
+        try:
+            category_slug = self.context['view'].kwargs.get('category_slug', 'all')
+        except (KeyError, AttributeError):
+            category_slug = ''
+        for key in settings_registry.get_registered_settings(category_slug=category_slug):
+            if self.instance and not hasattr(self.instance, key):
+                continue
+            extra_kwargs = {}
+            # Make LICENSE read-only here; update via /api/v1/config/ only.
+            if key == 'LICENSE':
+                extra_kwargs['read_only'] = True
+            field = settings_registry.get_setting_field(key, mixin_class=SettingFieldMixin, for_user=bool(category_slug == 'user'), **extra_kwargs)
+            fields[key] = field
+        return fields