Support listening on a Unix socket

When using nginx to terminate TLS (like it's done in Bifrost), it's more
secure to use a Unix socket for communication, so that local users
cannot access plain text communication.

Copies Inspector change I37b762cca035b5855deb92635c29e8eb97a87c20.

Change-Id: If00e5a3537b8fbaae3fa01f71bd515399464da36

ironic/common/wsgi_service.py

@@ -10,6 +10,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import socket
+
+from ironic_lib import utils as il_utils
 from oslo_concurrency import processutils
 from oslo_service import service
 from oslo_service import wsgi
@@ -46,6 +49,14 @@ class WSGIService(service.ServiceBase):
                 _("api_workers value of %d is invalid, "
                   "must be greater than 0.") % self.workers)
 
+        if CONF.api.unix_socket:
+            il_utils.unlink_without_raise(CONF.api.unix_socket)
+            self.server = wsgi.Server(CONF, name, self.app,
+                                      socket_family=socket.AF_UNIX,
+                                      socket_file=CONF.api.unix_socket,
+                                      socket_mode=CONF.api.unix_socket_mode,
+                                      use_ssl=use_ssl)
+        else:
             self.server = wsgi.Server(CONF, name, self.app,
                                       host=CONF.api.host_ip,
                                       port=CONF.api.port,
@@ -64,6 +75,8 @@ class WSGIService(service.ServiceBase):
         :returns: None
         """
         self.server.stop()
+        if CONF.api.unix_socket:
+            il_utils.unlink_without_raise(CONF.unix_socket)
 
     def wait(self):
         """Wait for the service to stop serving this API.

ironic/conf/api.py

@@ -15,9 +15,20 @@
 #    under the License.
 
 from oslo_config import cfg
+from oslo_config import types as cfg_types
 
 from ironic.common.i18n import _
 
+
+class Octal(cfg_types.Integer):
+
+    def __call__(self, value):
+        if isinstance(value, int):
+            return value
+        else:
+            return int(str(value), 8)
+
+
 opts = [
     cfg.HostAddressOpt('host_ip',
                        default='0.0.0.0',
@@ -26,6 +37,11 @@ opts = [
     cfg.PortOpt('port',
                 default=6385,
                 help=_('The TCP port on which ironic-api listens.')),
+    cfg.StrOpt('unix_socket',
+               help=_('Unix socket to listen on. Disables host_ip and port.')),
+    cfg.Opt('unix_socket_mode', type=Octal(),
+            help=_('File mode (an octal number) of the unix socket to '
+                   'listen on. Ignored if unix_socket is not set.')),
     cfg.IntOpt('max_limit',
                default=1000,
                mutable=True,

releasenotes/notes/unix-socket-48e8f1caf4cb19f9.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Supports listening on a Unix socket instead of a normal TCP socket.
+    This is useful with an HTTP server such as nginx in proxy mode.