CB-261: Authenticate requests to the Spotify Web API

critiquebrainz/frontend/external/exceptions.py

@@ -0,0 +1,7 @@
+class ExternalAPIException(Exception):
+    """Base exception for this package"""
+    pass
+
+class SpotifyWebAPIException(ExternalAPIException):
+    """Exception related to errors dealing with Spotify API."""
+    pass

critiquebrainz/frontend/external/spotify.py

@@ -6,12 +6,57 @@
 import requests
 import urllib.parse
 from brainzutils import cache
+from base64 import b64encode
+from flask import current_app as app
+from critiquebrainz.frontend.external.exceptions import SpotifyWebAPIException
 
 DEFAULT_CACHE_EXPIRATION = 12 * 60 * 60  # seconds (12 hours)
+ACCESS_TOKEN_EXPIRATION = 60 * 60 # seconds (1 hour)
 
 BASE_URL = "https://api.spotify.com/v1"
 
 
+def _fetch_access_token():
+    """Get an access token from the oauth credentials."""
+
+    key = cache.gen_key("spotify_access_token")
+    namespace = "spotify_access_token"
+    access_token = cache.get(key, namespace)
+
+    client_id = app.config.get("SPOTIFY_CLIENT_ID")
+    client_secret = app.config.get("SPOTIFY_CLIENT_SECRET")
+    auth_value = b64encode(bytes(f"{client_id}:{client_secret}", "utf-8")).decode("utf-8")
+
+    if not access_token:
+        access_token = requests.post(
+            "https://accounts.spotify.com/api/token",
+            data={"grant_type": "client_credentials"},
+            headers={"Authorization": f"Basic {auth_value}"},
+        ).json()
+        access_token = access_token.get('access_token')
+        if not access_token:
+            raise SpotifyWebAPIException("Could not fetch access token for Spotify API")
+        cache.set(key=key, namespace=namespace, val=access_token, time=ACCESS_TOKEN_EXPIRATION)
+    return access_token
+
+
+def _get_spotify(query):
+    """Make a GET request to Spotify Web API.
+
+    Args:
+        query (str): Query to the Web API.
+
+    Returns:
+        Dictionary containing the information.
+    """
+    access_token = _fetch_access_token()
+    url = BASE_URL + query
+    headers = {"Authorization": f"Bearer {access_token}"}
+
+    result = requests.get(f"{url}", headers=headers)
+    return result.json()
+
+
 def search(query, type, limit=20, offset=0):
     """Get Spotify catalog information about artists, albums, or tracks that
     match a keyword string.
@@ -22,9 +67,9 @@ def search(query, type, limit=20, offset=0):
     namespace = "spotify_search"
     result = cache.get(key, namespace)
     if not result:
-        result = requests.get("%s/search?q=%s&type=%s&limit=%s&offset=%s" %
-                              (BASE_URL, urllib.parse.quote(query.encode('utf8')),
-                               type, str(limit), str(offset))).json()
+        result = _get_spotify("/search?q=%s&type=%s&limit=%s&offset=%s" %
+                             (urllib.parse.quote(query.encode('utf8')),
+                             type, str(limit), str(offset)))
         cache.set(key=key, namespace=namespace, val=result,
                   time=DEFAULT_CACHE_EXPIRATION)
     return result
@@ -40,7 +85,7 @@ def get_album(spotify_id):
     namespace = "spotify_album"
     album = cache.get(spotify_id, namespace)
     if not album:
-        album = requests.get("%s/albums/%s" % (BASE_URL, spotify_id)).json()
+        album = _get_spotify("/albums/%s" % (spotify_id))
         cache.set(key=spotify_id, namespace=namespace, val=album,
                   time=DEFAULT_CACHE_EXPIRATION)
     return album
@@ -63,7 +108,7 @@ def get_multiple_albums(spotify_ids):
             spotify_ids.remove(album_id)
 
     if len(spotify_ids) > 0:
-        resp = requests.get("%s/albums?ids=%s" % (BASE_URL, ','.join(spotify_ids))).json()['albums']
+        resp = _get_spotify("/albums?ids=%s" % (','.join(spotify_ids)))["albums"]
 
         received_albums = {}
         for album in resp:

critiquebrainz/frontend/external/spotify_test.py

@@ -1,10 +1,11 @@
 from critiquebrainz.frontend.testing import FrontendTestCase
 from critiquebrainz.frontend.external import spotify
 
+BASE_URL = "https://api.spotify.com/v1"
 
 class FakeSpotifyResponse():
-    def __init__(self, url):
-        self.url = url
+    def __init__(self, query):
+        self.url = BASE_URL + query
 
     def json(self):
         return dict(url=self.url)
@@ -14,7 +15,7 @@ class SpotifyTestCase(FrontendTestCase):
 
     def setUp(self):
         super(SpotifyTestCase, self).setUp()
-        spotify.requests.get = lambda url: FakeSpotifyResponse(url)
+        spotify._get_spotify = lambda query: FakeSpotifyResponse(query).json()
         spotify.cache.get = lambda key, namespace=None: None
 
     def test_search(self):

custom_config.py.example

@@ -45,6 +45,9 @@ MUSICBRAINZ_CLIENT_SECRET = ""
 #MBSPOTIFY_BASE_URI = "https://mbspotify.musicbrainz.org/"
 #MBSPOTIFY_ACCESS_KEY = ""
 
+# Spotify
+#SPOTIFY_CLIENT_ID = ""
+#SPOTIFY_CLIENT_SECRET = ""
 
 # OTHER STUFF
 

default_config.py

@@ -59,6 +59,10 @@
 MUSICBRAINZ_CLIENT_ID = ""
 MUSICBRAINZ_CLIENT_SECRET = ""
 
+# Spotify
+SPOTIFY_CLIENT_ID = ""
+SPOTIFY_CLIENT_SECRET = ""
+
 # mbspotify
 # https://github.com/metabrainz/mbspotify
 MBSPOTIFY_BASE_URI = "https://mbspotify.musicbrainz.org/"

docs/intro.rst

@@ -14,15 +14,15 @@ First, you need to create custom configuration file. Copy the skeleton configura
 
    $ cp custom_config.py.example custom_config.py
 
-Then, open ``critiquebrainz/config.py`` in your favourite text editor and update
+Then, open ``critiquebrainz/custom_config.py`` in your favourite text editor and update
 any variables, as needed.
 
 Configuring MusicBrainz login
 '''''''''''''''''''''''''''''
 
 Before you begin using authentication with MusicBrainz accounts,
 you need to set ``MUSICBRAINZ_CLIENT_ID`` and ``MUSICBRAINZ_CLIENT_SECRET`` values.
-To obtain these keys, you need to register your instance of CrituqeBrainz on MusicBrainz.
+To obtain these keys, you need to register your instance of CritiqueBrainz on MusicBrainz.
 
 **Note** ``<your domain>`` field in the urls listed below should probably be set
 to ``localhost``, if you plan to run your CritiqueBrainz instance locally
@@ -35,9 +35,23 @@ In ``Callback URL`` field type::
    http://<your domain>/login/musicbrainz/post
 
 Finally, save the obtained ``OAuth Client ID`` and ``OAuth Client Secret`` fields
-in your ``config.py`` fields ``MUSICBRAINZ_CLIENT_ID`` and ``MUSICBRAINZ_CLIENT_SECRET``
+in your ``custom_config.py`` fields ``MUSICBRAINZ_CLIENT_ID`` and ``MUSICBRAINZ_CLIENT_SECRET``
 respectively.
 
+Configuring Spotfiy API authentication
+''''''''''''''''''''''''''''''''''''''
+
+To use the Spotify Web API in an instance of CritiqueBrainz, you need to set the
+``SPOTIFY_CLIENT_ID`` and ``SPOTIFY_CLIENT_SECRET`` values. To obtain the keys,
+register your instance of CritiqueBrainz on Spotify.
+
+After registering and logging into your Spotify account, head to
+https://developer.spotify.com/my-applications/ and then register your application following
+instructions on https://developer.spotify.com/web-api/tutorial/#registering-your-application.
+
+Finally, save the obtained ``Client ID`` and ``Client Secret`` fields in your ``custom_config.py``
+fields ``SPOTIFY_CLIENT_ID`` and ``SPOTIFY_CLIENT_SECRET`` respectively.
+
 Startup
 ^^^^^^^
 Then you can build all the services::