feat(emqx_bridge_kafka): add tcp keepalive option

Closes: EMQX-8725

apps/emqx_bridge_kafka/src/emqx_bridge_kafka.erl

@@ -74,7 +74,8 @@ values(common_config) ->
         socket_opts => #{
             sndbuf => <<"1024KB">>,
             recbuf => <<"1024KB">>,
-            nodelay => true
+            nodelay => true,
+            tcp_keepalive => <<"none">>
         }
     };
 values(producer) ->
@@ -236,7 +237,13 @@ fields(socket_opts) ->
                     importance => ?IMPORTANCE_HIDDEN,
                     desc => ?DESC(socket_nodelay)
                 }
-            )}
+            )},
+        {tcp_keepalive,
+            mk(string(), #{
+                default => <<"none">>,
+                desc => ?DESC(socket_tcp_keepalive),
+                validator => fun emqx_schema:validate_tcp_keepalive/1
+            })}
     ];
 fields(producer_opts) ->
     [

apps/emqx_bridge_kafka/src/emqx_bridge_kafka_impl.erl

@@ -8,9 +8,12 @@
 -export([
     hosts/1,
     make_client_id/2,
-    sasl/1
+    sasl/1,
+    socket_opts/1
 ]).
 
+-include_lib("emqx/include/logger.hrl").
+
 %% Parse comma separated host:port list into a [{Host,Port}] list
 hosts(Hosts) when is_binary(Hosts) ->
     hosts(binary_to_list(Hosts));
@@ -33,6 +36,51 @@ sasl(#{
 }) ->
     {callback, brod_gssapi, {gssapi, KeyTabFile, Principal}}.
 
+%% Extra socket options, such as sndbuf size etc.
+socket_opts(Opts) when is_map(Opts) ->
+    socket_opts(maps:to_list(Opts));
+socket_opts(Opts) when is_list(Opts) ->
+    socket_opts_loop(Opts, []).
+
+socket_opts_loop([], Acc) ->
+    lists:reverse(Acc);
+socket_opts_loop([{tcp_keepalive, KeepAlive} | Rest], Acc) ->
+    Acc1 = tcp_keepalive(KeepAlive) ++ Acc,
+    socket_opts_loop(Rest, Acc1);
+socket_opts_loop([{T, Bytes} | Rest], Acc) when
+    T =:= sndbuf orelse T =:= recbuf orelse T =:= buffer
+->
+    Acc1 = [{T, Bytes} | adjust_socket_buffer(Bytes, Acc)],
+    socket_opts_loop(Rest, Acc1);
+socket_opts_loop([Other | Rest], Acc) ->
+    socket_opts_loop(Rest, [Other | Acc]).
+
+%% https://www.erlang.org/doc/man/inet.html
+%% For TCP it is recommended to have val(buffer) >= val(recbuf)
+%% to avoid performance issues because of unnecessary copying.
+adjust_socket_buffer(Bytes, Opts) ->
+    case lists:keytake(buffer, 1, Opts) of
+        false ->
+            [{buffer, Bytes} | Opts];
+        {value, {buffer, Bytes1}, Acc1} ->
+            [{buffer, max(Bytes1, Bytes)} | Acc1]
+    end.
+
+tcp_keepalive(None) when None =:= "none"; None =:= <<"none">> ->
+    [];
+tcp_keepalive(KeepAlive) ->
+    {Idle, Interval, Probes} = emqx_schema:parse_tcp_keepalive(KeepAlive),
+    case emqx_utils:tcp_keepalive_opts(os:type(), Idle, Interval, Probes) of
+        {ok, Opts} ->
+            Opts;
+        {error, {unsupported_os, OS}} ->
+            ?SLOG(warning, #{
+                msg => "Unsupported operation: set TCP keepalive",
+                os => OS
+            }),
+            []
+    end.
+
 to_bin(A) when is_atom(A) ->
     atom_to_binary(A);
 to_bin(L) when is_list(L) ->

apps/emqx_bridge_kafka/src/emqx_bridge_kafka_impl_consumer.erl

@@ -131,6 +131,7 @@ on_start(ResourceId, Config) ->
             offset_commit_interval_seconds := _,
             offset_reset_policy := _
         },
+        socket_opts := SocketOpts0,
         ssl := SSL,
         topic_mapping := _
     } = Config,
@@ -144,8 +145,10 @@ on_start(ResourceId, Config) ->
             Auth -> [{sasl, emqx_bridge_kafka_impl:sasl(Auth)}]
         end,
     ClientOpts = add_ssl_opts(ClientOpts0, SSL),
+    SocketOpts = emqx_bridge_kafka_impl:socket_opts(SocketOpts0),
+    ClientOpts1 = [{extra_sock_opts, SocketOpts} | ClientOpts],
     ok = emqx_resource:allocate_resource(ResourceId, ?kafka_client_id, ClientID),
-    case brod:start_client(BootstrapHosts, ClientID, ClientOpts) of
+    case brod:start_client(BootstrapHosts, ClientID, ClientOpts1) of
         ok ->
             ?tp(
                 kafka_consumer_client_started,

apps/emqx_bridge_kafka/src/emqx_bridge_kafka_impl_producer.erl

@@ -61,7 +61,7 @@ on_start(InstId, Config) ->
         connect_timeout => ConnTimeout,
         client_id => ClientId,
         request_timeout => MetaReqTimeout,
-        extra_sock_opts => socket_opts(SocketOpts),
+        extra_sock_opts => emqx_bridge_kafka_impl:socket_opts(SocketOpts),
         sasl => emqx_bridge_kafka_impl:sasl(Auth),
         ssl => ssl(SSL)
     },
@@ -309,33 +309,6 @@ do_get_status(Client, KafkaTopic) ->
             disconnected
     end.
 
-%% Extra socket options, such as sndbuf size etc.
-socket_opts(Opts) when is_map(Opts) ->
-    socket_opts(maps:to_list(Opts));
-socket_opts(Opts) when is_list(Opts) ->
-    socket_opts_loop(Opts, []).
-
-socket_opts_loop([], Acc) ->
-    lists:reverse(Acc);
-socket_opts_loop([{T, Bytes} | Rest], Acc) when
-    T =:= sndbuf orelse T =:= recbuf orelse T =:= buffer
-->
-    Acc1 = [{T, Bytes} | adjust_socket_buffer(Bytes, Acc)],
-    socket_opts_loop(Rest, Acc1);
-socket_opts_loop([Other | Rest], Acc) ->
-    socket_opts_loop(Rest, [Other | Acc]).
-
-%% https://www.erlang.org/doc/man/inet.html
-%% For TCP it is recommended to have val(buffer) >= val(recbuf)
-%% to avoid performance issues because of unnecessary copying.
-adjust_socket_buffer(Bytes, Opts) ->
-    case lists:keytake(buffer, 1, Opts) of
-        false ->
-            [{buffer, Bytes} | Opts];
-        {value, {buffer, Bytes1}, Acc1} ->
-            [{buffer, max(Bytes1, Bytes)} | Acc1]
-    end.
-
 ssl(#{enable := true} = SSL) ->
     emqx_tls_lib:to_client_opts(SSL);
 ssl(_) ->

apps/emqx_bridge_kafka/test/emqx_bridge_kafka_tests.erl

@@ -168,6 +168,24 @@ message_key_dispatch_validations_test() ->
     ),
     ok.
 
+tcp_keepalive_validation_test_() ->
+    ProducerConf = parse(kafka_producer_new_hocon()),
+    ConsumerConf = parse(kafka_consumer_hocon()),
+    test_keepalive_validation([<<"kafka">>, <<"myproducer">>], ProducerConf) ++
+        test_keepalive_validation([<<"kafka_consumer">>, <<"my_consumer">>], ConsumerConf).
+
+test_keepalive_validation(Name, Conf) ->
+    Path = [<<"bridges">>] ++ Name ++ [<<"socket_opts">>, <<"tcp_keepalive">>],
+    Conf1 = emqx_utils_maps:deep_force_put(Path, Conf, <<"5,6,7">>),
+    Conf2 = emqx_utils_maps:deep_force_put(Path, Conf, <<"none">>),
+    ValidConfs = [Conf, Conf1, Conf2],
+    InvalidConf = emqx_utils_maps:deep_force_put(Path, Conf, <<"invalid">>),
+    InvalidConf1 = emqx_utils_maps:deep_force_put(Path, Conf, <<"5,6">>),
+    InvalidConf2 = emqx_utils_maps:deep_force_put(Path, Conf, <<"5,6,1000">>),
+    InvalidConfs = [InvalidConf, InvalidConf1, InvalidConf2],
+    [?_assertMatch(#{<<"bridges">> := _}, check(C)) || C <- ValidConfs] ++
+        [?_assertThrow(_, check(C)) || C <- InvalidConfs].
+
 %%===========================================================================
 %% Helper functions
 %%===========================================================================

changes/ee/feat-11003.en.md

@@ -0,0 +1 @@
+Add an option to configure TCP keepalive in Kafka bridge.

rel/i18n/emqx_bridge_kafka.hocon

@@ -38,6 +38,24 @@ socket_send_buffer.desc:
 socket_send_buffer.label:
 """Socket Send Buffer Size"""
 
+socket_receive_buffer.desc:
+"""Fine tune the socket receive buffer. The default value is tuned for high throughput."""
+
+socket_receive_buffer.label:
+"""Socket Receive Buffer Size"""
+
+socket_tcp_keepalive.desc:
+"""Enable TCP keepalive for Kafka bridge connections.
+The value is three comma separated numbers in the format of 'Idle,Interval,Probes'
+ - Idle: The number of seconds a connection needs to be idle before the server begins to send out keep-alive probes (Linux default 7200).
+ - Interval: The number of seconds between TCP keep-alive probes (Linux default 75).
+ - Probes: The maximum number of TCP keep-alive probes to send before giving up and killing the connection if no response is obtained from the other end (Linux default 9).
+For example "240,30,5" means: TCP keepalive probes are sent after the connection is idle for 240 seconds, and the probes are sent every 30 seconds until a response is received, if it misses 5 consecutive responses, the connection should be closed.
+Default: 'none'"""
+
+socket_tcp_keepalive.label:
+"""TCP keepalive options"""
+
 desc_name.desc:
 """Bridge name, used as a human-readable description of the bridge."""
 
@@ -56,12 +74,6 @@ consumer_max_batch_bytes.desc:
 consumer_max_batch_bytes.label:
 """Fetch Bytes"""
 
-socket_receive_buffer.desc:
-"""Fine tune the socket receive buffer. The default value is tuned for high throughput."""
-
-socket_receive_buffer.label:
-"""Socket Receive Buffer Size"""
-
 consumer_topic_mapping.desc:
 """Defines the mapping between Kafka topics and MQTT topics. Must contain at least one item."""