refactor: address the review comments

src/main.rs

@@ -369,7 +369,6 @@ fn start_discover(args: &args::Run, to_supervisor: ipc::Sender<IpcMessage>) {
     tarantool::set_cfg(&cfg);
 
     traft::Storage::init_schema();
-    traft::Storage::persist_cluster_id(&args.cluster_id).unwrap();
     discovery::init_global(&args.peers);
     init_handlers();
 
@@ -524,6 +523,8 @@ fn start_join(args: &args::Run, leader_address: String) {
     })
     .unwrap();
 
+    traft::Storage::persist_cluster_id(&args.cluster_id).unwrap();
+
     postjoin(args)
 }
 

src/traft/node.rs

@@ -49,8 +49,11 @@ pub enum Error {
     #[error("{0}")]
     Raft(#[from] RaftError),
     /// cluster_id of the joining peer mismatches the cluster_id of the cluster
-    #[error("cluster_id mismatches the cluster_id of the cluster")]
-    ClusterIdMismatch,
+    #[error("cannot join instance to the cluster: cluster_id mismatch: cluster_id of the instance = {instance_cluster_id:?}, cluster_id of the cluster = {cluster_cluster_id:?}")]
+    ClusterIdMismatch {
+        instance_cluster_id: String,
+        cluster_cluster_id: String,
+    },
 }
 
 #[derive(Clone, Debug, tlua::Push, tlua::PushInto)]
@@ -714,7 +717,10 @@ fn raft_join(req: JoinRequest) -> Result<JoinResponse, Box<dyn StdError>> {
     let cluster_id = Storage::cluster_id()?.ok_or("cluster_id is not set yet")?;
 
     if req.cluster_id != cluster_id {
-        return Err(Box::new(Error::ClusterIdMismatch));
+        return Err(Box::new(Error::ClusterIdMismatch {
+            instance_cluster_id: req.cluster_id,
+            cluster_cluster_id: cluster_id,
+        }));
     }
 
     let instance_id = req.instance_id.clone();

test/int/test_joining.py

+from functools import partial
 import os
 import errno
 import signal
@@ -64,27 +65,11 @@ def test_concurrency(cluster2: Cluster):
 
     # Subsequent requests get batched
     executor = ThreadPoolExecutor()
-    f1 = executor.submit(
-        raft_join,
-        peer=i1,
-        cluster_id=cluster2.id,
-        instance_id="fake-1",
-        timeout_seconds=5,
-    )
-    f2 = executor.submit(
-        raft_join,
-        peer=i1,
-        cluster_id=cluster2.id,
-        instance_id="fake-2",
-        timeout_seconds=5,
-    )
-    f3 = executor.submit(
-        raft_join,
-        peer=i1,
-        cluster_id=cluster2.id,
-        instance_id="fake-3",
-        timeout_seconds=0.1,
-    )
+    submit_join = partial(executor.submit, raft_join, peer=i1, cluster_id=cluster2.id)
+
+    f1 = submit_join(instance_id="fake-1", timeout_seconds=5)
+    f2 = submit_join(instance_id="fake-2", timeout_seconds=5)
+    f3 = submit_join(instance_id="fake-3", timeout_seconds=0.1)
 
     # Make sure all requests reach the server before resuming i2.
     with pytest.raises(OSError) as e1:
@@ -232,7 +217,10 @@ def test_cluster_id_mismatch(instance: Instance):
     assert wrong_cluster_id != instance.cluster_id
 
     with pytest.raises(
-        TarantoolError, match="cluster_id mismatches the cluster_id of the cluster"
+        TarantoolError,
+        match="cluster_id mismatch:"
+        ' cluster_id of the instance = "wrong-cluster-id",'
+        ' cluster_id of the cluster = "cluster-[^"]+"',
     ):
         raft_join(
             peer=instance,