Add shard id field to CLUSTER SHARDS response

src/cluster_legacy.c

@@ -6906,9 +6906,11 @@ void addNodeDetailsToShardReply(client *c, clusterNode *node) {
     setDeferredMapLen(c, node_replylen, reply_count);
 }
 
-/* Add to the output buffer of the given client, an array of slot (start, end)
- * pair owned by the shard, also the primary and set of replica(s) along with
- * information about each node. */
+/* Add to the output buffer of the given client,
+ * an array of slot (start, end) pair owned by the shard,
+ * an array of the primary and set of replica(s) along with information about each node,
+ * and shard id.
+ */
 void clusterCommandShards(client *c) {
     addReplyArrayLen(c, dictSize(server.cluster->shards));
     /* This call will add slot_info_pairs to all nodes */
@@ -6917,7 +6919,7 @@ void clusterCommandShards(client *c) {
     for (dictEntry *de = dictNext(di); de != NULL; de = dictNext(di)) {
         list *nodes = dictGetVal(de);
         serverAssert(listLength(nodes) > 0);
-        addReplyMapLen(c, 2);
+        addReplyMapLen(c, 3);
         addReplyBulkCString(c, "slots");
 
         /* Find a node which has the slot information served by this shard. */
@@ -6950,6 +6952,8 @@ void clusterCommandShards(client *c) {
             addNodeDetailsToShardReply(c, n);
             clusterFreeNodesSlotsInfo(n);
         }
+        addReplyBulkCString(c, "id");
+        addReplyBulkCBuffer(c, dictGetKey(de), CLUSTER_NAMELEN);
     }
     dictReleaseIterator(di);
 }

src/commands.def

@@ -1006,7 +1006,9 @@ struct COMMAND_ARG CLUSTER_SETSLOT_Args[] = {
 
 #ifndef SKIP_CMD_HISTORY_TABLE
 /* CLUSTER SHARDS history */
-#define CLUSTER_SHARDS_History NULL
+commandHistory CLUSTER_SHARDS_History[] = {
+{"9.0.0","Added shard id field to CLUSTER SHARDS response"},
+};
 #endif
 
 #ifndef SKIP_CMD_TIPS_TABLE
@@ -1165,7 +1167,7 @@ struct COMMAND_STRUCT CLUSTER_Subcommands[] = {
 {MAKE_CMD("saveconfig","Forces a node to save the cluster configuration to disk.","O(1)","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SAVECONFIG_History,0,CLUSTER_SAVECONFIG_Tips,0,clusterCommand,2,CMD_NO_ASYNC_LOADING|CMD_ADMIN|CMD_STALE,0,CLUSTER_SAVECONFIG_Keyspecs,0,NULL,0)},
 {MAKE_CMD("set-config-epoch","Sets the configuration epoch for a new node.","O(1)","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SET_CONFIG_EPOCH_History,0,CLUSTER_SET_CONFIG_EPOCH_Tips,0,clusterCommand,3,CMD_NO_ASYNC_LOADING|CMD_ADMIN|CMD_STALE,0,CLUSTER_SET_CONFIG_EPOCH_Keyspecs,0,NULL,1),.args=CLUSTER_SET_CONFIG_EPOCH_Args},
 {MAKE_CMD("setslot","Binds a hash slot to a node.","O(1)","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SETSLOT_History,1,CLUSTER_SETSLOT_Tips,0,clusterCommand,-4,CMD_NO_ASYNC_LOADING|CMD_ADMIN|CMD_STALE|CMD_MAY_REPLICATE,0,CLUSTER_SETSLOT_Keyspecs,0,NULL,3),.args=CLUSTER_SETSLOT_Args},
-{MAKE_CMD("shards","Returns the mapping of cluster slots to shards.","O(N) where N is the total number of cluster nodes","7.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SHARDS_History,0,CLUSTER_SHARDS_Tips,1,clusterCommand,2,CMD_LOADING|CMD_STALE,0,CLUSTER_SHARDS_Keyspecs,0,NULL,0)},
+{MAKE_CMD("shards","Returns the mapping of cluster slots to shards.","O(N) where N is the total number of cluster nodes","7.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SHARDS_History,1,CLUSTER_SHARDS_Tips,1,clusterCommand,2,CMD_LOADING|CMD_STALE,0,CLUSTER_SHARDS_Keyspecs,0,NULL,0)},
 {MAKE_CMD("slaves","Lists the replica nodes of a primary node.","O(N) where N is the number of replicas.","3.0.0",CMD_DOC_DEPRECATED,"`CLUSTER REPLICAS`","5.0.0","cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SLAVES_History,0,CLUSTER_SLAVES_Tips,1,clusterCommand,3,CMD_ADMIN|CMD_STALE,0,CLUSTER_SLAVES_Keyspecs,0,NULL,1),.args=CLUSTER_SLAVES_Args},
 {MAKE_CMD("slot-stats","Return an array of slot usage statistics for slots assigned to the current node.","O(N) where N is the total number of slots based on arguments. O(N*log(N)) with ORDERBY subcommand.","8.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SLOT_STATS_History,0,CLUSTER_SLOT_STATS_Tips,2,clusterSlotStatsCommand,-4,CMD_STALE|CMD_LOADING,0,CLUSTER_SLOT_STATS_Keyspecs,0,NULL,1),.args=CLUSTER_SLOT_STATS_Args},
 {MAKE_CMD("slots","Returns the mapping of cluster slots to nodes.","O(N) where N is the total number of Cluster nodes","3.0.0",CMD_DOC_NONE,NULL,NULL,"cluster",COMMAND_GROUP_CLUSTER,CLUSTER_SLOTS_History,2,CLUSTER_SLOTS_Tips,1,clusterCommand,2,CMD_LOADING|CMD_STALE,0,CLUSTER_SLOTS_Keyspecs,0,NULL,0)},

src/commands/cluster-shards.json

@@ -7,6 +7,12 @@
         "arity": 2,
         "container": "CLUSTER",
         "function": "clusterCommand",
+        "history": [
+            [
+                "9.0.0",
+                "Added shard id field to CLUSTER SHARDS response"
+            ]
+        ],
         "command_flags": [
             "LOADING",
             "STALE"
@@ -81,6 +87,10 @@
                                 }
                             }
                         }
+                    },
+                    "id": {
+                        "description": "A unique shard identifier.",
+                        "type": "string"
                     }
                 }
             }

tests/cluster/tests/28-cluster-shards.tcl

@@ -285,3 +285,28 @@ test "CLUSTER MYSHARDID reports same shard id after cluster restart" {
         assert_equal [dict get $node_ids $i] [R $i cluster myshardid]
     }
 }
+
+test "CLUSTER SHARDS id response validation" {
+    # For each node in the cluster
+    for {set i 0} {$i < $::cluster_master_nodes + $::cluster_replica_nodes} {incr i} {
+        # Get the CLUSTER SHARDS output from this node
+        set shards [R $i CLUSTER SHARDS]
+        set seen_shard_ids {}
+
+        # For each shard in the output
+        foreach shard $shards {
+            set shard_dict [dict create {*}$shard]
+
+            # 1. Verify 'id' key exists
+            assert {[dict exists $shard_dict id]}
+            set shard_id [dict get $shard_dict id]
+
+            # 2. Verify shard_id is a 40-char string
+            assert {[string length $shard_id] == 40}
+
+            # 3. Verify that for a given node's output, all shard IDs are unique
+            assert {[dict exists $seen_shard_ids $shard_id] == 0}
+            dict set seen_shard_ids $shard_id 1
+        }
+    }
+}