Make default homeserver config use bind_addresses

Signed-off-by: Johannes Löthberg <johannes@kyriasis.com>

synapse/config/server.py

@@ -155,9 +155,10 @@ class ServerConfig(Config):
             # The port to listen for HTTPS requests on.
             port: %(bind_port)s
 
-            # Local interface to listen on.
-            # The empty string will cause synapse to listen on all interfaces.
-            bind_address: ''
+            # Local addresses to listen on.
+            # This will listen on all IPv4 addresses by default.
+            bind_addresses:
+              - '0.0.0.0'
 
             # This is a 'http' listener, allows us to specify 'resources'.
             type: http
@@ -188,7 +189,7 @@ class ServerConfig(Config):
           # For when matrix traffic passes through loadbalancer that unwraps TLS.
           - port: %(unsecure_port)s
             tls: false
-            bind_address: ''
+            bind_addresses: ['0.0.0.0']
             type: http
 
             x_forwarded: false