fix(machine_boot): ensure `emqx_bridge` starts after its companion apps

We need to reverse the dependency of `emqx_bridge` and `emqx_bridge_*`, because the former
loads and starts bridges during its application startup.  If the individual bridge
application being loaded has not started with its dependencies, the supervision tree will
not be ready for that.

apps/emqx_bridge_cassandra/src/emqx_bridge_cassandra.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         ecql
     ]},
     {env, []},

apps/emqx_bridge_clickhouse/src/emqx_bridge_clickhouse.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         clickhouse
     ]},
     {env, []},

apps/emqx_bridge_dynamo/src/emqx_bridge_dynamo.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         erlcloud
     ]},
     {env, []},

apps/emqx_bridge_gcp_pubsub/src/emqx_bridge_gcp_pubsub.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge_http,
         ehttpc
     ]},
     {env, []},

apps/emqx_bridge_gcp_pubsub/test/emqx_bridge_gcp_pubsub_consumer_SUITE.erl

@@ -598,6 +598,7 @@ start_cluster(Cluster) ->
         end,
         Cluster
     ),
+    NumNodes = length(Nodes),
     on_exit(fun() ->
         emqx_utils:pmap(
             fun(N) ->
@@ -607,6 +608,11 @@ start_cluster(Cluster) ->
             Nodes
         )
     end),
+    {ok, _} = snabbkaffe:block_until(
+        %% -1 because only those that join the first node will emit the event.
+        ?match_n_events(NumNodes - 1, #{?snk_kind := emqx_machine_boot_apps_started}),
+        30_000
+    ),
     Nodes.
 
 wait_for_cluster_rpc(Node) ->

apps/emqx_bridge_hstreamdb/src/emqx_bridge_hstreamdb.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         hstreamdb_erl
     ]},
     {env, []},

apps/emqx_bridge_http/src/emqx_bridge_http.app.src

@@ -2,7 +2,7 @@
     {description, "EMQX HTTP Bridge and Connector Application"},
     {vsn, "0.1.1"},
     {registered, []},
-    {applications, [kernel, stdlib, emqx_connector, emqx_resource, emqx_bridge, ehttpc]},
+    {applications, [kernel, stdlib, emqx_connector, emqx_resource, ehttpc]},
     {env, []},
     {modules, []},
     {links, []}

apps/emqx_bridge_influxdb/src/emqx_bridge_influxdb.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         influxdb
     ]},
     {env, []},

apps/emqx_bridge_iotdb/src/emqx_bridge_iotdb.app.src

@@ -11,7 +11,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge_http,
         %% for module emqx_connector_http
         emqx_connector
     ]},

apps/emqx_bridge_kafka/src/emqx_bridge_kafka.app.src

@@ -7,7 +7,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         telemetry,
         wolff,
         brod,

apps/emqx_bridge_kafka/test/emqx_bridge_kafka_impl_consumer_SUITE.erl

@@ -1071,13 +1071,14 @@ cluster(Config) ->
     Cluster = emqx_common_test_helpers:emqx_cluster(
         [core, core],
         [
-            {apps, [emqx_conf, emqx_bridge, emqx_rule_engine, emqx_bridge_kafka]},
+            {apps, [emqx_conf, emqx_rule_engine, emqx_bridge_kafka, emqx_bridge]},
             {listener_ports, []},
             {peer_mod, PeerModule},
             {priv_data_dir, PrivDataDir},
             {load_schema, true},
             {start_autocluster, true},
             {schema_mod, emqx_enterprise_schema},
+            {load_apps, [emqx_machine]},
             {env_handler, fun
                 (emqx) ->
                     application:set_env(emqx, boot_modules, [broker, router]),
@@ -1901,6 +1902,7 @@ t_cluster_node_down(Config) ->
     ?check_trace(
         begin
             {_N2, Opts2} = lists:nth(2, Cluster),
+            NumNodes = length(Cluster),
             Nodes =
                 [N1, N2 | _] =
                 lists:map(
@@ -1925,6 +1927,11 @@ t_cluster_node_down(Config) ->
                 15_000
             ),
             wait_for_cluster_rpc(N2),
+            {ok, _} = snabbkaffe:block_until(
+                %% -1 because only those that join the first node will emit the event.
+                ?match_n_events(NumNodes - 1, #{?snk_kind := emqx_machine_boot_apps_started}),
+                30_000
+            ),
             erpc:call(N2, fun() -> {ok, _} = create_bridge(Config) end),
             {ok, _} = snabbkaffe:receive_events(SRef0),
             lists:foreach(
@@ -1980,7 +1987,7 @@ t_cluster_node_down(Config) ->
             ?assertEqual(NPartitions, map_size(Assignments)),
             NumPublished = ets:info(TId, size),
             %% All published messages are eventually received.
-            Published = receive_published(#{n => NumPublished, timeout => 3_000}),
+            Published = receive_published(#{n => NumPublished, timeout => 10_000}),
             ct:pal("published:\n  ~p", [Published]),
             ok
         end

apps/emqx_bridge_matrix/src/emqx_bridge_matrix.app.src

@@ -5,8 +5,7 @@
     {applications, [
         kernel,
         stdlib,
-        emqx_resource,
-        emqx_bridge
+        emqx_resource
     ]},
     {env, []},
     {modules, []},

apps/emqx_bridge_mongodb/src/emqx_bridge_mongodb.app.src

@@ -7,7 +7,6 @@
         stdlib,
         emqx_connector,
         emqx_resource,
-        emqx_bridge,
         emqx_mongodb
     ]},
     {env, []},

apps/emqx_bridge_mqtt/src/emqx_bridge_mqtt.app.src

@@ -1,14 +1,13 @@
 %% -*- mode: erlang -*-
 {application, emqx_bridge_mqtt, [
     {description, "EMQX MQTT Broker Bridge"},
-    {vsn, "0.1.2"},
+    {vsn, "0.1.3"},
     {registered, []},
     {applications, [
         kernel,
         stdlib,
         emqx,
         emqx_resource,
-        emqx_bridge,
         emqtt
     ]},
     {env, []},

apps/emqx_bridge_mysql/src/emqx_bridge_mysql.app.src

@@ -7,7 +7,6 @@
         stdlib,
         emqx_connector,
         emqx_resource,
-        emqx_bridge,
         emqx_mysql
     ]},
     {env, []},

apps/emqx_bridge_opents/src/emqx_bridge_opents.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         opentsdb
     ]},
     {env, []},

apps/emqx_bridge_oracle/src/emqx_bridge_oracle.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         emqx_oracle
     ]},
     {env, []},

apps/emqx_bridge_pgsql/src/emqx_bridge_pgsql.app.src

@@ -5,8 +5,7 @@
     {applications, [
         kernel,
         stdlib,
-        emqx_resource,
-        emqx_bridge
+        emqx_resource
     ]},
     {env, []},
     {modules, []},

apps/emqx_bridge_pulsar/src/emqx_bridge_pulsar.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         pulsar
     ]},
     {env, []},

apps/emqx_bridge_rabbitmq/src/emqx_bridge_rabbitmq.app.src

@@ -6,8 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
-        ecql,
         rabbit_common,
         amqp_client
     ]},

apps/emqx_bridge_redis/src/emqx_bridge_redis.app.src

@@ -7,7 +7,6 @@
         stdlib,
         emqx_connector,
         emqx_resource,
-        emqx_bridge,
         emqx_redis
     ]},
     {env, []},

apps/emqx_bridge_rocketmq/src/emqx_bridge_rocketmq.app.src

@@ -2,7 +2,7 @@
     {description, "EMQX Enterprise RocketMQ Bridge"},
     {vsn, "0.1.3"},
     {registered, []},
-    {applications, [kernel, stdlib, emqx_resource, emqx_bridge, rocketmq]},
+    {applications, [kernel, stdlib, emqx_resource, rocketmq]},
     {env, []},
     {modules, []},
     {links, []}

apps/emqx_bridge_sqlserver/src/emqx_bridge_sqlserver.app.src

@@ -2,7 +2,7 @@
     {description, "EMQX Enterprise SQL Server Bridge"},
     {vsn, "0.1.2"},
     {registered, []},
-    {applications, [kernel, stdlib, emqx_resource, emqx_bridge, odbc]},
+    {applications, [kernel, stdlib, emqx_resource, odbc]},
     {env, []},
     {modules, []},
     {links, []}

apps/emqx_bridge_tdengine/src/emqx_bridge_tdengine.app.src

@@ -6,7 +6,6 @@
         kernel,
         stdlib,
         emqx_resource,
-        emqx_bridge,
         tdengine
     ]},
     {env, []},

apps/emqx_bridge_timescale/src/emqx_bridge_timescale.app.src

@@ -2,7 +2,7 @@
     {description, "EMQX Enterprise TimescaleDB Bridge"},
     {vsn, "0.1.2"},
     {registered, []},
-    {applications, [kernel, stdlib, emqx_resource, emqx_bridge]},
+    {applications, [kernel, stdlib, emqx_resource]},
     {env, []},
     {modules, []},
     {links, []}

apps/emqx_machine/src/emqx_machine_boot.erl

@@ -160,7 +160,8 @@ is_app(Name) ->
     end.
 
 sorted_reboot_apps() ->
-    Apps = [{App, app_deps(App)} || App <- reboot_apps()],
+    Apps0 = [{App, app_deps(App)} || App <- reboot_apps()],
+    Apps = inject_bridge_deps(Apps0),
     sorted_reboot_apps(Apps).
 
 app_deps(App) ->
@@ -169,6 +170,25 @@ app_deps(App) ->
         {ok, List} -> lists:filter(fun(A) -> lists:member(A, reboot_apps()) end, List)
     end.
 
+%% `emqx_bridge' is special in that it needs all the bridges apps to
+%% be started before it, so that, when it loads the bridges from
+%% configuration, the bridge app and its dependencies need to be up.
+inject_bridge_deps(RebootAppDeps) ->
+    BridgeApps = [
+        App
+     || {App, _Deps} <- RebootAppDeps,
+        lists:prefix("emqx_bridge_", atom_to_list(App))
+    ],
+    lists:map(
+        fun
+            ({emqx_bridge, Deps0}) when is_list(Deps0) ->
+                {emqx_bridge, Deps0 ++ BridgeApps};
+            (App) ->
+                App
+        end,
+        RebootAppDeps
+    ).
+
 sorted_reboot_apps(Apps) ->
     G = digraph:new(),
     try