Issue #23630, asyncio: host parameter of loop.create_server() can now be a

sequence of strings. Patch written by Yann Sionneau.

Lib/asyncio/base_events.py

@@ -18,6 +18,7 @@ import collections
 import concurrent.futures
 import heapq
 import inspect
+import itertools
 import logging
 import os
 import socket
@@ -786,6 +787,15 @@ class BaseEventLoop(events.AbstractEventLoop):
 
         return transport, protocol
 
+    @coroutine
+    def _create_server_getaddrinfo(self, host, port, family, flags):
+        infos = yield from self.getaddrinfo(host, port, family=family,
+                                            type=socket.SOCK_STREAM,
+                                            flags=flags)
+        if not infos:
+            raise OSError('getaddrinfo({!r}) returned empty list'.format(host))
+        return infos
+
     @coroutine
     def create_server(self, protocol_factory, host=None, port=None,
                       *,
@@ -795,7 +805,13 @@ class BaseEventLoop(events.AbstractEventLoop):
                       backlog=100,
                       ssl=None,
                       reuse_address=None):
-        """Create a TCP server bound to host and port.
+        """Create a TCP server.
+
+        The host parameter can be a string, in that case the TCP server is bound
+        to host and port.
+
+        The host parameter can also be a sequence of strings and in that case
+        the TCP server is bound to all hosts of the sequence.
 
         Return a Server object which can be used to stop the service.
 
@@ -813,13 +829,18 @@ class BaseEventLoop(events.AbstractEventLoop):
                 reuse_address = os.name == 'posix' and sys.platform != 'cygwin'
             sockets = []
             if host == '':
-                host = None
+                hosts = [None]
+            elif (isinstance(host, str) or
+                  not isinstance(host, collections.Iterable)):
+                hosts = [host]
+            else:
+                hosts = host
 
-            infos = yield from self.getaddrinfo(
-                host, port, family=family,
-                type=socket.SOCK_STREAM, proto=0, flags=flags)
-            if not infos:
-                raise OSError('getaddrinfo() returned empty list')
+            fs = [self._create_server_getaddrinfo(host, port, family=family,
+                                                  flags=flags)
+                  for host in hosts]
+            infos = yield from tasks.gather(*fs, loop=self)
+            infos = itertools.chain.from_iterable(infos)
 
             completed = False
             try:

Lib/asyncio/events.py

@@ -305,7 +305,8 @@ class AbstractEventLoop:
 
         If host is an empty string or None all interfaces are assumed
         and a list of multiple sockets will be returned (most likely
-        one for IPv4 and another one for IPv6).
+        one for IPv4 and another one for IPv6). The host parameter can also be a
+        sequence (e.g. list) of hosts to bind to.
 
         family can be set to either AF_INET or AF_INET6 to force the
         socket to use IPv4 or IPv6. If not set it will be determined