Reworked TAAR as a plugin for a webservice

* Reworked taar so that it exports an entrypoint for use by taar-api
* An application wrapper is required to facilitate instrumentation of
  state within TAAR when it is under test.
* bumped to version 0.1.1

setup.py

@@ -3,7 +3,7 @@ from setuptools import find_packages, setup
 setup(
     name='mozilla-taar3',
     use_scm_version=False,
-    version='0.0.28',
+    version='0.1.1',
     setup_requires=['setuptools_scm', 'pytest-runner'],
     tests_require=['pytest'],
     include_package_data = True,
@@ -33,5 +33,9 @@ setup(
         'Topic :: Internet :: WWW/HTTP',
         'Topic :: Scientific/Engineering :: Information Analysis'
     ],
+    entry_points="""
+    [taarapi_app]
+    app=taar.plugin:configure_plugin
+    """,
     zip_safe=False,
 )

taar/plugin.py

@@ -0,0 +1,114 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from decouple import config
+from flask import request
+import json
+
+# TAAR specific libraries
+from taar.context import default_context
+from taar.profile_fetcher import ProfileFetcher
+from taar import recommenders
+from taar import ProfileController
+
+# These are configurations that are specific to the TAAR library
+VALID_BRANCHES = set(['linear', 'ensemble', 'control'])
+DYNAMO_REGION = config('DYNAMO_REGION', default='us-west-2')
+DYNAMO_TABLE_NAME = config('DYNAMO_TABLE_NAME', default='taar_addon_data_20180206')
+TAAR_MAX_RESULTS = config('TAAR_MAX_RESULTS', default=10, cast=int)
+
+
+class ResourceProxy(object):
+    def __init__(self):
+        self._resource = None
+
+    def setResource(self, rsrc):
+        self._resource = rsrc
+
+    def getResource(self):
+        return self._resource
+
+
+PROXY_MANAGER = ResourceProxy()
+
+
+def configure_plugin(app):
+    """
+    This is a factory function that configures all the routes for
+    flask given a particular library.
+    """
+    @app.route('/api/recommendations/<uuid:uuid_client_id>/')
+    def recommendations(uuid_client_id):
+        """Return a list of recommendations provided a telemetry client_id."""
+        # Use the module global PROXY_MANAGER
+        global PROXY_MANAGER
+
+        # Coerce the uuid.UUID type into a string
+        client_id = str(uuid_client_id)
+
+        branch = request.args.get('branch', '')
+
+        if branch.endswith('-taar'):
+            branch = branch.replace("-taar", "")
+
+        if branch not in VALID_BRANCHES:
+            # Force branch to be a control branch if an invalid request
+            # comes in.
+            branch = 'control'
+
+        extra_data = {'branch': branch}
+
+        locale = request.args.get('locale', None)
+        if locale is not None:
+            extra_data['locale'] = locale
+
+        platform = request.args.get('platform', None)
+        if platform is not None:
+            extra_data['platform'] = platform
+
+        if PROXY_MANAGER.getResource() is None:
+            ctx = default_context()
+            dynamo_client = ProfileController(region_name=DYNAMO_REGION,
+                                              table_name=DYNAMO_TABLE_NAME)
+            profile_fetcher = ProfileFetcher(dynamo_client)
+
+            ctx['profile_fetcher'] = profile_fetcher
+
+            # Lock the context down after we've got basic bits installed
+            root_ctx = ctx.child()
+            r_factory = recommenders.RecommenderFactory(root_ctx)
+            root_ctx['recommender_factory'] = r_factory
+            instance = recommenders.RecommendationManager(root_ctx.child())
+            PROXY_MANAGER.setResource(instance)
+
+        instance = PROXY_MANAGER.getResource()
+        recommendations = instance.recommend(client_id=client_id,
+                                             limit=TAAR_MAX_RESULTS,
+                                             extra_data=extra_data)
+        # Strip out weights from TAAR results to maintain compatibility
+        # with TAAR 1.0
+        jdata = {"results": [x[0] for x in recommendations]}
+
+        response = app.response_class(
+                response=json.dumps(jdata),
+                status=200,
+                mimetype='application/json'
+                )
+        return response
+
+    class MyPlugin:
+        def set(self, config_options):
+            """
+            This setter is primarily so that we can instrument the
+            cached RecommendationManager implementation under test.
+
+            All plugins should implement this set method to enable
+            overwriting configuration options with a TAAR library.
+            """
+            global PROXY_MANAGER
+            if 'PROXY_RESOURCE' in config_options:
+                PROXY_MANAGER._resource = config_options['PROXY_RESOURCE']
+
+    return MyPlugin()
+