Make mqtt.subscription_ttl unsupported

Starting with RabbitMQ 3.13 mqtt.max_session_expiry_interval_seconds
(set in seconds) will replace the previous setting
mqtt.subscription_ttl.

MQTT 5.0 introduces the Session Expiry Interval
feature which does not only apply to subscribers, but also to
publishers.

The new config name mqtt.max_session_expiry_interval_seconds makes it clear
that it also applies to publishers.

Prior to this commit, when mqtt.subscription_ttl was set, a warning got
logged and the value was ignored. This is dangerous if an operator does
not see the warning but relies for example on `mqtt.subscription =
infinity` to not expire non clean session.

It's safer to make the boot fail if that unsupported config name is
still set. A clear error message will be logged:
```
[error] <0.142.0> Error preparing configuration in phase apply_translations:
[error] <0.142.0>   - Translation for 'rabbitmq_mqtt.subscription_ttl' found invalid configuration:
        Since 3.13 mqtt.subscription_ttl (in milliseconds) is unsupported.
        Use mqtt.max_session_expiry_interval_seconds (in seconds) instead.
```

Alternatively, RabbitMQ could translate mqtt.subscription_ttl to
mqtt.max_session_expiry_interval_seconds.

However, forcing the new config option sounds the better way to go.

Once we write MQTT 5.0 docs, this change must go into the 3.13 release notes.

This commit also renames max_session_expiry_interval_secs to max_session_expiry_interval_seconds.
The latter is clearer to users.

deps/rabbit/docs/rabbitmq.conf.example

@@ -913,7 +913,7 @@
 ## 'infinity' means the session does not expire.
 ## An MQTT 5.0 client can choose a lower value.
 ##
-# mqtt.max_session_expiry_interval_secs = 1800
+# mqtt.max_session_expiry_interval_seconds = 1800
 
 ## Set the prefetch count (governing the maximum number of unacknowledged
 ## messages that will be delivered).

deps/rabbitmq_mqtt/BUILD.bazel

@@ -34,7 +34,7 @@ APP_ENV = """[
 	    {allow_anonymous, true},
 	    {vhost, <<"/">>},
 	    {exchange, <<"amq.topic">>},
-	    {max_session_expiry_interval_secs, 86400}, %% 1 day
+	    {max_session_expiry_interval_seconds, 86400}, %% 1 day
 	    {retained_message_store, rabbit_mqtt_retained_msg_store_dets},
 	    %% only used by DETS store
 	    {retained_message_store_dets_sync_interval, 2000},

deps/rabbitmq_mqtt/Makefile

@@ -11,7 +11,7 @@ define PROJECT_ENV
 	    {allow_anonymous, true},
 	    {vhost, <<"/">>},
 	    {exchange, <<"amq.topic">>},
-	    {max_session_expiry_interval_secs, 86400}, %% 1 day
+	    {max_session_expiry_interval_seconds, 86400}, %% 1 day
 	    {retained_message_store, rabbit_mqtt_retained_msg_store_dets},
 	    %% only used by DETS store
 	    {retained_message_store_dets_sync_interval, 2000},

deps/rabbitmq_mqtt/priv/schema/rabbitmq_mqtt.schema

@@ -71,24 +71,22 @@ end}.
 
 {translation, "rabbitmq_mqtt.subscription_ttl",
 fun(Conf) ->
-    cuttlefish:warn(
-            "Since 3.13 mqtt.subscription_ttl (in milliseconds) is deprecated and "
-            "has no effect anymore. Use mqtt.max_session_expiry_interval_secs (in "
-            "seconds) instead."),
-    cuttlefish:unset()
+    cuttlefish:invalid(
+        "Since 3.13 mqtt.subscription_ttl (in milliseconds) is unsupported. "
+        "Use mqtt.max_session_expiry_interval_seconds (in seconds) instead.")
 end}.
 
 %% Defines the maximum Session Expiry Interval in seconds allowed by the server.
 %% 'infinity' means the session does not expire.
 %% An MQTT 5.0 client can choose a lower value.
 
-{mapping, "mqtt.max_session_expiry_interval_secs", "rabbitmq_mqtt.max_session_expiry_interval_secs", [
+{mapping, "mqtt.max_session_expiry_interval_seconds", "rabbitmq_mqtt.max_session_expiry_interval_seconds", [
     {datatype, [integer, {atom, infinity}]}
 ]}.
 
-{translation, "rabbitmq_mqtt.max_session_expiry_interval_secs",
+{translation, "rabbitmq_mqtt.max_session_expiry_interval_seconds",
 fun(Conf) ->
-    case cuttlefish:conf_get("mqtt.max_session_expiry_interval_secs", Conf) of
+    case cuttlefish:conf_get("mqtt.max_session_expiry_interval_seconds", Conf) of
         N when is_integer(N) andalso N < 0 ->
             cuttlefish:invalid("negative integer not allowed");
         Valid ->

deps/rabbitmq_mqtt/src/rabbit_mqtt_processor.erl

@@ -148,7 +148,7 @@ process_connect(
     MaxPacketSize = maps:get('Maximum-Packet-Size', ConnectProps, ?MAX_PACKET_SIZE),
     TopicAliasMax = persistent_term:get(?PERSISTENT_TERM_TOPIC_ALIAS_MAXIMUM),
     TopicAliasMaxOutbound = min(maps:get('Topic-Alias-Maximum', ConnectProps, 0), TopicAliasMax),
-    {ok, MaxSessionExpiry} = application:get_env(?APP_NAME, max_session_expiry_interval_secs),
+    {ok, MaxSessionExpiry} = application:get_env(?APP_NAME, max_session_expiry_interval_seconds),
     SessionExpiry =
     case {ProtoVer, CleanStart} of
         {5, _} ->
@@ -157,7 +157,7 @@ process_connect(
                 ?UINT_MAX ->
                     %% "If the Session Expiry Interval is 0xFFFFFFFF (UINT_MAX),
                     %% the Session does not expire."
-                    min(infinity, MaxSessionExpiry);
+                    MaxSessionExpiry;
                 Seconds ->
                     min(Seconds, MaxSessionExpiry)
             end;
@@ -569,7 +569,7 @@ process_request(?DISCONNECT,
             State0;
         _ ->
             %% "The session expiry interval can be modified at disconnect."
-            {ok, MaxSEI} = application:get_env(?APP_NAME, max_session_expiry_interval_secs),
+            {ok, MaxSEI} = application:get_env(?APP_NAME, max_session_expiry_interval_seconds),
             NewSEI = min(RequestedSEI, MaxSEI),
             lists:foreach(fun(QName) ->
                                   update_session_expiry_interval(QName, NewSEI)

deps/rabbitmq_mqtt/test/config_schema_SUITE_data/rabbitmq_mqtt.snippets

@@ -5,7 +5,7 @@
    mqtt.allow_anonymous  = true
    mqtt.vhost            = /
    mqtt.exchange         = amq.topic
-   mqtt.max_session_expiry_interval_secs = 1800
+   mqtt.max_session_expiry_interval_seconds = 86400
    mqtt.prefetch         = 10
    mqtt.sparkplug      = true
    mqtt.listeners.ssl    = none
@@ -25,7 +25,7 @@
         {allow_anonymous,true},
         {vhost,<<"/">>},
         {exchange,<<"amq.topic">>},
-        {max_session_expiry_interval_secs,1800},
+        {max_session_expiry_interval_seconds,86400},
         {prefetch,10},
         {sparkplug,true},
         {ssl_listeners,[]},
@@ -106,7 +106,7 @@
    mqtt.allow_anonymous  = true
    mqtt.vhost            = /
    mqtt.exchange         = amq.topic
-   mqtt.max_session_expiry_interval_secs = infinity
+   mqtt.max_session_expiry_interval_seconds = infinity
    mqtt.prefetch         = 10
    mqtt.proxy_protocol = true",
   [{rabbit,[{tcp_listeners,[5672]}]},
@@ -116,7 +116,7 @@
         {allow_anonymous,true},
         {vhost,<<"/">>},
         {exchange,<<"amq.topic">>},
-        {max_session_expiry_interval_secs,infinity},
+        {max_session_expiry_interval_seconds,infinity},
         {prefetch,10},
         {proxy_protocol,true}]}],
   [rabbitmq_mqtt]},
@@ -126,7 +126,7 @@
    mqtt.allow_anonymous  = true
    mqtt.vhost            = /
    mqtt.exchange         = amq.topic
-   mqtt.max_session_expiry_interval_secs = 1800
+   mqtt.max_session_expiry_interval_seconds = 1800
    mqtt.prefetch         = 10
 ## use DETS (disk-based) store for retained messages
    mqtt.retained_message_store = rabbit_mqtt_retained_msg_store_dets
@@ -141,7 +141,7 @@
         {allow_anonymous,true},
         {vhost,<<"/">>},
         {exchange,<<"amq.topic">>},
-        {max_session_expiry_interval_secs,1800},
+        {max_session_expiry_interval_seconds,1800},
         {prefetch,10},
         {retained_message_store,rabbit_mqtt_retained_msg_store_dets},
         {retained_message_store_dets_sync_interval,2000},

deps/rabbitmq_mqtt/test/shared_SUITE.erl

@@ -824,7 +824,7 @@ delete_create_queue(Config) ->
 
 session_expiry(Config) ->
     App = rabbitmq_mqtt,
-    Par = max_session_expiry_interval_secs,
+    Par = max_session_expiry_interval_seconds,
     Seconds = 1,
     {ok, DefaultVal} = rpc(Config, application, get_env, [App, Par]),
     ok = rpc(Config, application, set_env, [App, Par, Seconds]),

deps/rabbitmq_mqtt/test/v5_SUITE.erl

@@ -198,7 +198,7 @@ init_per_testcase(T, Config)
   when T =:= session_expiry_disconnect_infinity_to_zero;
        T =:= session_expiry_disconnect_to_infinity;
        T =:= session_expiry_reconnect_infinity_to_zero ->
-    Par = max_session_expiry_interval_secs,
+    Par = max_session_expiry_interval_seconds,
     {ok, Default} = rpc(Config, application, get_env, [?APP, Par]),
     ok = rpc(Config, application, set_env, [?APP, Par, infinity]),
     Config1 = rabbit_ct_helpers:set_config(Config, {Par, Default}),
@@ -215,7 +215,7 @@ end_per_testcase(T, Config)
   when T =:= session_expiry_disconnect_infinity_to_zero;
        T =:= session_expiry_disconnect_to_infinity;
        T =:= session_expiry_reconnect_infinity_to_zero ->
-    Par = max_session_expiry_interval_secs,
+    Par = max_session_expiry_interval_seconds,
     Default = ?config(Par, Config),
     ok = rpc(Config, application, set_env, [?APP, Par, Default]),
     end_per_testcase0(T, Config);