feat(rpc): add ipv6_only config

apps/emqx_conf/src/emqx_conf_schema.erl

@@ -957,6 +957,16 @@ fields("rpc") ->
                     desc => ?DESC(rpc_listen_address),
                     importance => ?IMPORTANCE_MEDIUM
                 }
+            )},
+        {"ipv6_only",
+            sc(
+                boolean(),
+                #{
+                    default => false,
+                    mapping => "gen_rpc.ipv6_only",
+                    desc => ?DESC(rpc_ipv6_only),
+                    importance => ?IMPORTANCE_LOW
+                }
             )}
     ];
 fields("log") ->

rel/i18n/emqx_conf_schema.hocon

@@ -195,11 +195,18 @@ rpc_insecure_fallback.label:
 """RPC insecure fallback"""
 
 rpc_listen_address.desc:
-"""Specify which IP address the RPC server should listen on.
+"""Indicates the IP address for the RPC server to listen on. For example, use <code>"0.0.0.0"</code> for IPv4 or <code>"::"</code> for IPv6."""
-For example <code>"0.0.0.0"</code> (default) for IPv4 and <code>"::"</code> for IPv6"""
 
 rpc_listen_address.label:
-"""RPC Listen Address"""
+"""RPC Listen IP Address"""
+
+rpc_ipv6_only.desc:
+"""This setting is effective only when <code>rpc.listen_address</code> is assigned an IPv6 address.
+If set to <code>true</code>, the RPC client will exclusively use IPv6 for connections.
+Otherwise, the client might opt for IPv4, even if the server is on IPv6."""
+
+rpc_ipv6_only.label:
+"""Use IPv6 Only"""
 
 cluster_mcast_buffer.desc:
 """Size of the user-level buffer."""