Add the option to use path-style S3 URLs.

docs/index.rst

@@ -184,6 +184,11 @@ uploading assets to S3.
                             bucket name in the base url.
 `S3_BUCKET_NAME`            The desired name for your Amazon S3 bucket. Note:
                             the name will be visible in all your assets' URLs.
+`S3_URL_STYLE`              Set to `'host'` to use virtual-host-style URLs,
+                            e.g. ``bucketname.s3.amazonaws.com``. Set to
+                            `'path'` to use path-style URLs, e.g.
+                            ``s3.amazonaws.com/bucketname``.
+                            **Default:** `'host'`
 `S3_USE_HTTPS`              Specifies whether or not to serve your assets
                             stored in S3 over HTTPS.
                             **Default:** `True`

flask_s3.py

@@ -33,8 +33,20 @@ def url_for(endpoint, **values):
         scheme = 'http'
         if app.config['S3_USE_HTTPS']:
             scheme = 'https'
-        bucket_path = '%s.%s' % (app.config['S3_BUCKET_NAME'],
-                                 app.config['S3_BUCKET_DOMAIN'])
+
+        if app.config['S3_URL_STYLE'] == 'host':
+            url_format = '%(bucket_name)s.%(bucket_domain)s'
+        elif app.config['S3_URL_STYLE'] == 'path':
+            url_format = '%(bucket_domain)s/%(bucket_name)s'
+        else:
+            raise ValueError('Invalid S3 URL style: "%s"'
+                             % app.config['S3_URL_STYLE'])
+
+        bucket_path = url_format % {
+            'bucket_name': app.config['S3_BUCKET_NAME'],
+            'bucket_domain': app.config['S3_BUCKET_DOMAIN'],
+        }
+
         if app.config['S3_CDN_DOMAIN']:
             bucket_path = '%s' % app.config['S3_CDN_DOMAIN']
         urls = app.url_map.bind(bucket_path, url_scheme=scheme)
@@ -220,7 +232,8 @@ def init_app(self, app):
                     ('S3_BUCKET_DOMAIN', 's3.amazonaws.com'),
                     ('S3_CDN_DOMAIN', ''),
                     ('S3_USE_CACHE_CONTROL', False),
-                    ('S3_HEADERS', {})]
+                    ('S3_HEADERS', {}),
+                    ('S3_URL_STYLE', 'host')]
 
         for k, v in defaults:
             app.config.setdefault(k, v)

tests/test_flask_static.py

@@ -30,7 +30,8 @@ def test_config(self):
         FlaskS3(self.app)
         defaults = ('S3_USE_HTTPS', 'USE_S3', 'USE_S3_DEBUG',
                     'S3_BUCKET_DOMAIN', 'S3_CDN_DOMAIN',
-                    'S3_USE_CACHE_CONTROL', 'S3_HEADERS')
+                    'S3_USE_CACHE_CONTROL', 'S3_HEADERS',
+                    'S3_URL_STYLE')
         for default in defaults:
             self.assertIn(default, self.app.config)
 
@@ -121,6 +122,18 @@ def test_url_for_cdn_domain(self):
         exp = 'https://foo.cloudfront.net/static/bah.js'
         self.assertEquals(self.client_get(ufs).data, exp)
 
+    def test_url_for_url_style_path(self):
+        """Tests that the URL returned uses the path style."""
+        self.app.config['S3_URL_STYLE'] = 'path'
+        ufs = "{{url_for('static', filename='bah.js')}}"
+        exp = 'https://s3.amazonaws.com/foo/static/bah.js'
+        self.assertEquals(self.client_get(ufs).data, exp)
+
+    def test_url_for_url_style_invalid(self):
+        """Tests that an exception is raised for invalid URL styles."""
+        self.app.config['S3_URL_STYLE'] = 'balderdash'
+        ufs = "{{url_for('static', filename='bah.js')}}"
+        self.assertRaises(ValueError, self.client_get, ufs)
 
 
 class S3Tests(unittest.TestCase):