fix(obs): label node-local metrics by server (#5465)

Add stable server labels to node-local Prometheus metrics and OTLP resource attributes so dashboards can distinguish per-node CPU, memory, host network, and internode traffic series.

Co-authored-by: heihutu <heihutu@gmail.com>

crates/obs/src/node_identity.rs

@@ -0,0 +1,34 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub(crate) const RUSTFS_NODE_ATTRIBUTE: &str = "rustfs.node";
+pub(crate) const SERVER_LABEL: &str = "server";
+
+#[cfg(test)]
+static LOCAL_NODE_IDENTITY_TEST_LOCK: std::sync::LazyLock<tokio::sync::Mutex<()>> =
+    std::sync::LazyLock::new(|| tokio::sync::Mutex::new(()));
+
+pub(crate) fn local_node_identity(local_ip: &str) -> String {
+    rustfs_common::try_get_global_local_node_name().unwrap_or_else(|| local_ip.to_string())
+}
+
+pub(crate) fn current_local_node_identity() -> String {
+    let local_ip = rustfs_utils::get_local_ip_with_default();
+    local_node_identity(&local_ip)
+}
+
+#[cfg(test)]
+pub(crate) async fn local_node_identity_test_guard() -> tokio::sync::MutexGuard<'static, ()> {
+    LOCAL_NODE_IDENTITY_TEST_LOCK.lock().await
+}