From bdcc069aac5c0b31666a4e7d63854d44620d6cae Mon Sep 17 00:00:00 2001
From: "Zaiming (Stone) Shi" <zmstone@gmail.com>
Date: Mon, 5 Jun 2023 14:58:33 +0200
Subject: [PATCH 1/2] chore: start deprecating mcast cluster discovery

---
 apps/emqx_conf/src/emqx_conf_schema.erl | 4 ++--
 rel/i18n/emqx_conf_schema.hocon         | 4 +++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/apps/emqx_conf/src/emqx_conf_schema.erl b/apps/emqx_conf/src/emqx_conf_schema.erl
index b4ba2bf47..f339f78a3 100644
--- a/apps/emqx_conf/src/emqx_conf_schema.erl
+++ b/apps/emqx_conf/src/emqx_conf_schema.erl
@@ -143,7 +143,7 @@ fields("cluster") ->
             )},
         {"discovery_strategy",
             sc(
-                hoconsc:enum([manual, static, mcast, dns, etcd, k8s]),
+                hoconsc:enum([manual, static, dns, etcd, k8s, mcast]),
                 #{
                     default => manual,
                     desc => ?DESC(cluster_discovery_strategy),
@@ -198,7 +198,7 @@ fields("cluster") ->
         {"mcast",
             sc(
                 ?R_REF(cluster_mcast),
-                #{}
+                #{importance => ?IMPORTANCE_HIDDEN}
             )},
         {"dns",
             sc(
diff --git a/rel/i18n/emqx_conf_schema.hocon b/rel/i18n/emqx_conf_schema.hocon
index 079132454..416b3ca76 100644
--- a/rel/i18n/emqx_conf_schema.hocon
+++ b/rel/i18n/emqx_conf_schema.hocon
@@ -755,7 +755,9 @@ cluster_discovery_strategy.desc:
 - static: Configure static nodes list by setting <code>seeds</code> in config file.<br/>
 - dns: Use DNS A record to discover peer nodes.<br/>
 - etcd: Use etcd to discover peer nodes.<br/>
-- k8s: Use Kubernetes API to discover peer pods."""
+- k8s: Use Kubernetes API to discover peer pods.
+- mcast: Deprecated since 5.1, will be removed in 5.2.
+  This supports discovery via UDP multicast."""
 
 cluster_discovery_strategy.label:
 """Cluster Discovery Strategy"""

From 1dd2109b1fcbc8d787e6132cd9cb3eb166b3a418 Mon Sep 17 00:00:00 2001
From: "Zaiming (Stone) Shi" <zmstone@gmail.com>
Date: Mon, 5 Jun 2023 15:03:21 +0200
Subject: [PATCH 2/2] docs: add changelog for 10943

---
 changes/ce/fix-10943.en.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 changes/ce/fix-10943.en.md

diff --git a/changes/ce/fix-10943.en.md b/changes/ce/fix-10943.en.md
new file mode 100644
index 000000000..081f94c24
--- /dev/null
+++ b/changes/ce/fix-10943.en.md
@@ -0,0 +1,5 @@
+Deprecated UDP mcast mechanism for cluster discovery.
+
+This feature has been planed for deprecation since 5.0 mainly due to the lack of
+actual production use.
+This feature code is not yet removed in 5.1, but the document interface is demoted.