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,
+ * an array of shard info, like shard-id and so on
+ */
 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 +6952,10 @@ void clusterCommandShards(client *c) {
             addNodeDetailsToShardReply(c, n);
             clusterFreeNodesSlotsInfo(n);
         }
+        addReplyBulkCString(c, "shard");
+        addReplyMapLen(c, 1);
+        addReplyBulkCString(c, "id");
+        addReplyBulkCBuffer(c, dictGetKey(de), CLUSTER_NAMELEN);
     }
     dictReleaseIterator(di);
 }

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

@@ -285,3 +285,33 @@ 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 'shard' key exists
+            assert {[dict exists $shard_dict shard]}
+            set shard_info [dict get $shard_dict shard]
+            set shard_info_dict [dict create {*}$shard_info]
+
+            # 2. Verify 'id' key exists in the nested shard info
+            assert {[dict exists $shard_info_dict id]}
+            set shard_id [dict get $shard_info_dict id]
+
+            # 3. Verify shard_id is a 40-char string
+            assert {[string length $shard_id] == 40}
+
+            # 4. 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
+        }
+    }
+}