SSL support for gaiohttp worker

Initialize and pass `SSLContext` to `asyncio.loop.create_server` to enable ssl support.

gunicorn/workers/_gaiohttp.py

@@ -7,6 +7,12 @@ import asyncio
 import functools
 import logging
 import os
+
+try:
+    import ssl
+except ImportError:
+    ssl = None
+
 import gunicorn.workers.base as base
 
 from aiohttp.wsgi import WSGIServerHttpProtocol
@@ -16,7 +22,11 @@ class AiohttpWorker(base.Worker):
 
     def __init__(self, *args, **kw):  # pragma: no cover
         super().__init__(*args, **kw)
-
+        cfg = self.cfg
+        if cfg.is_ssl:
+            self.ssl_context = self._create_ssl_context(cfg)
+        else:
+            self.ssl_context = None
         self.servers = []
         self.connections = {}
 
@@ -74,7 +84,7 @@ class AiohttpWorker(base.Worker):
         for sock in self.sockets:
             factory = self.get_factory(sock.sock, sock.cfg_addr)
             self.servers.append(
-                (yield from self.loop.create_server(factory, sock=sock.sock)))
+                (yield from self._create_server(factory, sock)))
 
         # If our parent changed then we shut down.
         pid = os.getpid()
@@ -112,6 +122,26 @@ class AiohttpWorker(base.Worker):
 
         yield from self.close()
 
+    @asyncio.coroutine
+    def _create_server(self, factory, sock):
+        return self.loop.create_server(factory, sock=sock.sock,
+                                       ssl=self.ssl_context)
+
+    @staticmethod
+    def _create_ssl_context(cfg):
+        """ Creates SSLContext instance for usage in asyncio.create_server.
+
+        See ssl.SSLSocket.__init__ for more details.
+        """
+        ctx = ssl.SSLContext(cfg.ssl_version)
+        ctx.load_cert_chain(cfg.certfile, cfg.keyfile)
+        ctx.verify_mode = cfg.cert_reqs
+        if cfg.ca_certs:
+            ctx.load_verify_locations(cfg.ca_certs)
+        if cfg.ciphers:
+            ctx.set_ciphers(cfg.ciphers)
+        return ctx
+
 
 class _wrp: