Making TCP_KEEPIDLE socket option optional

Not all implementations of the python socket library support
TCP_KEEPIDLE, so only try to set it when supported. Fixes bug 879195.

Change-Id: I2f062a346a60c69f52d23f70332d7c9da4ecdf35

glance/common/wsgi.py

@@ -98,7 +98,11 @@ def get_socket(host, port, conf):
     sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
     # in my experience, sockets can hang around forever without keepalive
     sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
-    sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 600)
+
+    # This option isn't available in the OS X version of eventlet
+    if hasattr(socket, 'TCP_KEEPIDLE'):
+        sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 600)
+
     return sock