Add support for settings wsgi MAX_HEADER_LINE

Changes default from 8192 to 16384 and adds a configuration option.

Change-Id: Ia6dc883c60e32e54124fc4d9e5853021c861c284
Closes-Bug: 1453591

designate/api/__init__.py

@@ -38,4 +38,9 @@ cfg.CONF.register_opts([
     cfg.BoolOpt('enable-api-v1', default=True),
     cfg.BoolOpt('enable-api-v2', default=False),
     cfg.BoolOpt('enable-api-admin', default=False),
+    cfg.IntOpt('max_header_line', default=16384,
+               help="Maximum line size of message headers to be accepted. "
+                    "max_header_line may need to be increased when using "
+                    "large tokens (typically those generated by the "
+                    "Keystone v3 API with big service catalogs)."),
 ], group='service:api')

designate/service.py

@@ -219,6 +219,9 @@ class WSGIService(object):
 
     def _wsgi_handle(self, application, socket):
         logger = logging.getLogger('eventlet.wsgi')
+        # Adjust wsgi MAX_HEADER_LINE to accept large tokens.
+        eventlet.wsgi.MAX_HEADER_LINE = self._service_config.max_header_line
+
         eventlet.wsgi.server(socket,
                              application,
                              custom_pool=self.tg.pool,

etc/designate/designate.conf.sample

@@ -75,6 +75,11 @@ debug = False
 # Port the bind the API server to
 #api_port = 9001
 
+# Maximum line size of message headers to be accepted. max_header_line may
+# need to be increased when using large tokens (typically those generated by
+# the Keystone v3 API with big service catalogs).
+#max_header_line = 16384
+
 # Authentication strategy to use - can be either "noauth" or "keystone"
 #auth_strategy = keystone