From 98868c36151cff660328ec4bfd9bb757036bfa17 Mon Sep 17 00:00:00 2001
From: Thales Macedo Garitezi <16166434+thalesmg@users.noreply.github.com>
Date: Thu, 7 Nov 2024 13:38:20 -0300
Subject: [PATCH] fix(publish api): return 200 for delayed messages

Fixes https://emqx.atlassian.net/browse/EMQX-12780

Fixes https://github.com/emqx/emqx/issues/13215
---
 .../src/emqx_mgmt_api_publish.erl             |  2 ++
 .../test/emqx_mgmt_api_publish_SUITE.erl      | 21 +++++++++++++++++++
 changes/ce/fix-14182.en.md                    |  1 +
 3 files changed, 24 insertions(+)
 create mode 100644 changes/ce/fix-14182.en.md

diff --git a/apps/emqx_management/src/emqx_mgmt_api_publish.erl b/apps/emqx_management/src/emqx_mgmt_api_publish.erl
index 9b5de578fc6..dd8fda9d414 100644
--- a/apps/emqx_management/src/emqx_mgmt_api_publish.erl
+++ b/apps/emqx_management/src/emqx_mgmt_api_publish.erl
@@ -272,6 +272,8 @@ is_ok_deliver({_NodeOrShare, _MatchedTopic, {error, _}}) -> false.
 %% No preceding payload format indicator to compare against.
 %% Content-Type check should be done at HTTP layer but not here.
 %% 153                Payload format invalid                  400
+publish_result_to_http_reply(#message{topic = <<"$delayed/", _/binary>>} = Message, []) ->
+    {?ALL_IS_WELL, make_publish_response(Message)};
 publish_result_to_http_reply(_Message, []) ->
     %% matched no subscriber
     {?PARTIALLY_OK, make_publish_error_response(?RC_NO_MATCHING_SUBSCRIBERS)};
diff --git a/apps/emqx_management/test/emqx_mgmt_api_publish_SUITE.erl b/apps/emqx_management/test/emqx_mgmt_api_publish_SUITE.erl
index 0e4b8aece44..d833442b669 100644
--- a/apps/emqx_management/test/emqx_mgmt_api_publish_SUITE.erl
+++ b/apps/emqx_management/test/emqx_mgmt_api_publish_SUITE.erl
@@ -407,6 +407,27 @@ t_publish_offline_api(_) ->
     ResponseMap = decode_json(Response),
     ?assertEqual([<<"id">>], lists:sort(maps:keys(ResponseMap))).
 
+%% Checks that we return HTTP response status code 200 for delayed messages, even if there
+%% are no subscribers at the time of publishing.
+t_delayed_message_always_200({init, Config}) ->
+    Config;
+t_delayed_message_always_200({'end', _Config}) ->
+    ok;
+t_delayed_message_always_200(Config) when is_list(Config) ->
+    Request = #{
+        <<"topic">> => <<"$delayed/1/t">>,
+        <<"payload">> => <<"delayed">>
+    },
+    ?assertMatch(
+        {200, #{<<"id">> := _}},
+        emqx_mgmt_api_test_util:simple_request(
+            post,
+            emqx_mgmt_api_test_util:api_path(["publish"]),
+            Request
+        )
+    ),
+    ok.
+
 receive_assert(Topic, Qos, Payload) ->
     receive
         {publish, Message} ->
diff --git a/changes/ce/fix-14182.en.md b/changes/ce/fix-14182.en.md
new file mode 100644
index 00000000000..428556acec6
--- /dev/null
+++ b/changes/ce/fix-14182.en.md
@@ -0,0 +1 @@
+Previously, if a delayed message was published via the `POST /publish` HTTP API, a 202 reponse with the reason code 16 ("no matching subscribers") would be returned.  Now, a 200 response is sent along with the message identifier.