feat: LISTEN_ADDRESS accepts multiple addresses

src/func_python/cloudevent.py

@@ -2,16 +2,17 @@
 import logging
 import os
 import signal
-import socket
+
 import hypercorn.config
 import hypercorn.asyncio
 
 from cloudevents.http import from_http, CloudEvent
 from cloudevents.conversion import to_structured, to_binary
 from cloudevents.exceptions import MissingRequiredFields, InvalidRequiredFields
 
+import func_python.sock
+
 DEFAULT_LOG_LEVEL = logging.INFO
-DEFAULT_LISTEN_ADDRESS = "[::]:8080"
 
 logging.basicConfig(level=DEFAULT_LOG_LEVEL)
 
@@ -75,13 +76,7 @@ def serve(self):
         """serve serving this ASGIhandler, delegating implementation of
            methods as necessary to the wrapped Function instance"""
         cfg = hypercorn.config.Config()
-
-        la = os.getenv('LISTEN_ADDRESS', DEFAULT_LISTEN_ADDRESS)
-        [host, port] = la.rsplit(":", 1)
-        # fixup for IPv4-only machines
-        if not socket.has_ipv6 and host == '[::]':
-            la = "0.0.0.0:" + port
-        cfg.bind = [la]
+        cfg.bind = func_python.sock.bind()
 
         logging.info(f"function starting on {cfg.bind}")
         return asyncio.run(self._serve(cfg))

src/func_python/http.py

@@ -3,12 +3,13 @@
 import logging
 import os
 import signal
-import socket
+
 import hypercorn.config
 import hypercorn.asyncio
 
+import func_python.sock
+
 DEFAULT_LOG_LEVEL = logging.INFO
-DEFAULT_LISTEN_ADDRESS = "[::]:8080"
 
 logging.basicConfig(level=DEFAULT_LOG_LEVEL)
 
@@ -70,13 +71,7 @@ def serve(self):
         """serve serving this ASGIhandler, delegating implementation of
            methods as necessary to the wrapped Function instance"""
         cfg = hypercorn.config.Config()
-
-        la = os.getenv('LISTEN_ADDRESS', DEFAULT_LISTEN_ADDRESS)
-        [host, port] = la.rsplit(":", 1)
-        # fixup for IPv4-only machines
-        if not socket.has_ipv6 and host == '[::]':
-            la = "0.0.0.0:" + port
-        cfg.bind = [la]
+        cfg.bind = func_python.sock.bind()
 
         logging.debug(f"function starting on {cfg.bind}")
         return asyncio.run(self._serve(cfg))

src/func_python/sock.py

@@ -0,0 +1,73 @@
+import ipaddress
+import logging
+import os
+import socket
+
+
+DEFAULT_LISTEN_ADDRESS = '[::]:8080,0.0.0.0:8080'
+
+def bind() -> list[str]:
+    """
+    This function reads the 'LISTEN_ADDRESS' environment variable and binds sockets according to it's content.
+    This function gives us some more control over how sockets are created.
+    We creat them ourselves here, and forward them in the "fd://{fd}" format to the hypercorn server.
+    :return: Sequence of "bind" strings in format expected by the hypercorn server config.
+    """
+
+    listen_addresses = os.getenv('LISTEN_ADDRESS', DEFAULT_LISTEN_ADDRESS).split(",")
+
+    fixup_ipv4_unspecified(listen_addresses)
+
+    ipv4_only = not socket.has_dualstack_ipv6()
+    result: list[str] = []
+
+    for address in listen_addresses:
+        if address.startswith("unix://") or address.startswith("fd://"):
+            logging.error(f'unsupported schema: <{address}>')
+            continue
+        sock: socket.socket
+
+        [host, port] = address.rsplit(":", 1)
+        if '[' in host:
+            if ipv4_only:
+                logging.warning(f'not binding <{address}> since IPv6 is not available')
+                continue
+            host = host.strip('[]')
+            sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
+            try:
+                sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 1)
+            except socket.error as e:
+                logging.warning(f"cannot set IPV6_V6ONLY: {e}")
+        else:
+            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+
+        try:
+            sock.bind((host, int(port)))
+            result.append(f'fd://{sock.detach()}')
+        except socket.error as e:
+            logging.error(f"cannot bind socket <{address}>: {e}")
+
+    if len(result) <= 0:
+        raise Exception('failed to bind any sockets')
+
+    return result
+
+def fixup_ipv4_unspecified(listen_addresses: list[str]) -> None:
+    """
+    This function checks if the listen addresses contains unspecified IPv6 address but not unspecified IPv4 address.
+    If that's the case the function will insert appropriate unspecified IPv4 address into the list.
+    """
+    ipv6_unspecified_port = None
+    ipv4_unspecified = False
+    for la in listen_addresses:
+        if la.startswith("unix://") or la.startswith("fd://"):
+            continue
+        [host,port] = la.rsplit(":", 1)
+        ip = ipaddress.ip_address(host.strip('[]'))
+        if ip.is_unspecified:
+            if isinstance(ip, ipaddress.IPv6Address):
+                ipv6_unspecified_port = port
+            if isinstance(ip, ipaddress.IPv4Address):
+                ipv4_unspecified = True
+    if ipv6_unspecified_port is not None and not ipv4_unspecified:
+        listen_addresses.append('0.0.0.0:' + ipv6_unspecified_port)