fix(rpc): add issue 2815 regression and docker validation (#2828)

rustfs/src/storage/rpc/mod.rs

@@ -36,6 +36,7 @@ pub(crate) fn encode_msgpack_map<T: Serialize>(value: &T) -> Result<Vec<u8>, rmp
 mod tests {
     use super::*;
     use rmp_serde::Deserializer;
+    use rustfs_madmin::{BackendDisks, BackendInfo, Disk, ITEM_ONLINE, StorageInfo};
     use serde::Deserialize;
     use std::collections::HashMap;
     use std::io::Cursor;
@@ -90,4 +91,66 @@ mod tests {
         let decoded: Nested = Deserialize::deserialize(&mut Deserializer::new(Cursor::new(&buf))).unwrap();
         assert_eq!(val, decoded);
     }
+
+    #[test]
+    fn storage_info_map_encoding_round_trip_matches_issue_2815_contract() {
+        let mut online_disks = BackendDisks::new();
+        online_disks.0.insert("node1".into(), 4);
+        let mut offline_disks = BackendDisks::new();
+        offline_disks.0.insert("node2".into(), 0);
+
+        let value = StorageInfo {
+            disks: vec![Disk {
+                endpoint: "node1:9000".into(),
+                state: ITEM_ONLINE.into(),
+                local: true,
+                pool_index: 0,
+                set_index: 0,
+                disk_index: 0,
+                ..Default::default()
+            }],
+            backend: BackendInfo {
+                online_disks,
+                offline_disks,
+                total_sets: vec![1],
+                drives_per_set: vec![4],
+                ..Default::default()
+            },
+        };
+
+        let buf = encode_msgpack_map(&value).unwrap();
+        let marker = buf[0];
+        assert!(
+            (0x80..=0x8f).contains(&marker) || marker == 0xde || marker == 0xdf,
+            "StorageInfo map-encoded payload must start with a map marker, got 0x{marker:02x}"
+        );
+        let decoded: StorageInfo = Deserialize::deserialize(&mut Deserializer::new(Cursor::new(&buf))).unwrap();
+
+        assert_eq!(decoded.disks.len(), 1);
+        assert_eq!(decoded.disks[0].endpoint, "node1:9000");
+        assert_eq!(decoded.backend.online_disks.0.get("node1"), Some(&4));
+        assert_eq!(decoded.backend.offline_disks.0.get("node2"), Some(&0));
+    }
+
+    #[test]
+    fn storage_info_tuple_encoding_uses_array_marker_that_issue_2815_fixed() {
+        let mut online_disks = BackendDisks::new();
+        online_disks.0.insert("node1".into(), 4);
+
+        let value = StorageInfo {
+            backend: BackendInfo {
+                online_disks,
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+
+        let mut buf = Vec::new();
+        value.serialize(&mut Serializer::new(&mut buf)).unwrap();
+        let marker = buf[0];
+        assert!(
+            (0x90..=0x9f).contains(&marker) || marker == 0xdc || marker == 0xdd,
+            "legacy tuple-mode StorageInfo must start with an array marker, got 0x{marker:02x}"
+        );
+    }
 }