test(ds): Attempt to stabilize metrics_worker tests in CI

apps/emqx_durable_storage/src/emqx_ds_replication_layer_egress.erl

@@ -221,7 +221,6 @@ do_flush(
             emqx_ds_builtin_metrics:inc_egress_batches(Metrics),
             emqx_ds_builtin_metrics:inc_egress_messages(Metrics, S#s.n),
             emqx_ds_builtin_metrics:inc_egress_bytes(Metrics, S#s.n_bytes),
-            lists:foreach(fun(From) -> gen_server:reply(From, ok) end, Replies),
             ?tp(
                 emqx_ds_replication_layer_egress_flush,
                 #{db => DB, shard => Shard, batch => Messages}

apps/emqx_durable_storage/test/emqx_ds_test_helpers.erl

@@ -64,10 +64,11 @@ consume(DB, TopicFilter) ->
 
 consume(DB, TopicFilter, StartTime) ->
     lists:flatmap(
-      fun({_Stream, Msgs}) ->
-              Msgs
-      end,
-      consume_per_stream(DB, TopicFilter, StartTime)).
+        fun({_Stream, Msgs}) ->
+            Msgs
+        end,
+        consume_per_stream(DB, TopicFilter, StartTime)
+    ).
 
 consume_per_stream(DB, TopicFilter, StartTime) ->
     Streams = emqx_ds:get_streams(DB, TopicFilter, StartTime),

apps/emqx_utils/test/emqx_metrics_worker_SUITE.erl

@@ -31,18 +31,17 @@ suite() ->
 -define(NAME, ?MODULE).
 
 init_per_suite(Config) ->
-    {ok, _} = emqx_metrics_worker:start_link(?NAME),
     Config.
 
 end_per_suite(_Config) ->
-    ok = emqx_metrics_worker:stop(?NAME).
+    ok.
 
 init_per_testcase(_, Config) ->
-    ok = emqx_metrics_worker:stop(?NAME),
     {ok, _} = emqx_metrics_worker:start_link(?NAME),
     Config.
 
 end_per_testcase(_, _Config) ->
+    ok = emqx_metrics_worker:stop(?NAME),
     ok.
 
 t_get_metrics(_) ->

changes/ce/feat-12781.en.md

@@ -0,0 +1,29 @@
+Added metrics related to EMQX durable storage to Prometheus.
+
+New metrics:
+
+- `emqx_ds_egress_batches`
+
+- `emqx_ds_egress_batches_retry`
+
+- `emqx_ds_egress_batches_failed`
+
+- `emqx_ds_egress_messages`
+
+- `emqx_ds_egress_bytes`
+
+- `emqx_ds_egress_flush_time`
+
+- `emqx_ds_store_batch_time`
+
+- `emqx_ds_builtin_next_time`
+
+- `emqx_ds_storage_bitfield_lts_counter_seek`
+
+- `emqx_ds_storage_bitfield_lts_counter_next`
+
+- `emqx_ds_storage_bitfield_lts_counter_collision`
+
+Note: these metrics are only visible when session persistence is enabled.
+
+Number of persisted messages has been also added to the dashboard.