Add option to handle SSL termination proxies

ooi needs to return URLs of objects matching the URL scheme used
for serving the application even if ooi is behind a SSL termination
proxy.

A new configuration variable "ooi_secure_proxy_ssl_header" that
defines the HTTP header that can be used to update the wsgi.url_scheme
environment variable. Typical value for this variable is
'HTTP_X_FORWARDED_PROTO'.

Change-Id: I7ce7583f64778f667a7ea310d493390d9e19f1e2
Closes-Bug: #1676844

ooi/tests/unit/test_wsgi.py

@@ -16,6 +16,7 @@ import webob
 import webob.dec
 import webob.exc
 
+from ooi import config
 from ooi.tests import base
 from ooi import wsgi
 
@@ -160,6 +161,12 @@ class TestMiddleware(base.TestCase):
         result = req.get_response(self.app)
         self.assertEqual(404, result.status_code)
 
+    def test_ssl_middleware(self):
+        config.cfg.CONF.set_override('ooi_secure_proxy_ssl_header', 'bar')
+        request = wsgi.Request.blank("/foos", method="GET",
+                                     environ={'bar': 'baz'})
+        self.assertEqual('baz', request.environ['wsgi.url_scheme'])
+
 
 class TestOCCIMiddleware(base.TestCase):
     def setUp(self):

ooi/wsgi/__init__.py

@@ -48,6 +48,12 @@ occi_opts = [
                       help='Number of workers for OCCI (ooi) API service. '
                            'The default will be equal to the number of CPUs '
                            'available.'),
+    config.cfg.StrOpt('ooi_secure_proxy_ssl_header',
+                      default=None,
+                      help='The HTTP header used to determine the scheme '
+                           'for the original request, even if it was '
+                           'removed by an SSL terminating proxy. Typical '
+                           'value is "HTTP_X_FORWARDED_PROTO".'),
     # NEUTRON
     config.cfg.StrOpt('neutron_ooi_endpoint',
                       default=None,
@@ -60,6 +66,13 @@ CONF.register_opts(occi_opts)
 
 
 class Request(webob.Request):
+    def __init__(self, environ, *args, **kwargs):
+        if CONF.ooi_secure_proxy_ssl_header:
+            scheme = environ.get(CONF.ooi_secure_proxy_ssl_header)
+            if scheme:
+                environ['wsgi.url_scheme'] = scheme
+        super(Request, self).__init__(environ, *args, **kwargs)
+
     def should_have_body(self):
         return self.method in ("POST", "PUT")