refactor(obs): migrate metrics runtime/schema and tighten migration guards (#2584)

crates/obs/src/metrics/schema/node_disk.rs

@@ -0,0 +1,51 @@
+// 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.
+
+#![allow(dead_code)]
+
+use crate::{MetricDescriptor, MetricName, MetricSubsystem, new_gauge_md};
+use std::sync::LazyLock;
+
+const SERVER_LABEL: &str = "server";
+const DRIVE_LABEL: &str = "drive";
+
+/// Total disk capacity in bytes
+pub static NODE_DISK_TOTAL_BYTES_MD: LazyLock<MetricDescriptor> = LazyLock::new(|| {
+    new_gauge_md(
+        MetricName::Custom("disk_total_bytes".to_string()),
+        "Total disk capacity in bytes",
+        &[SERVER_LABEL, DRIVE_LABEL],
+        MetricSubsystem::new("/node"),
+    )
+});
+
+/// Used disk space in bytes
+pub static NODE_DISK_USED_BYTES_MD: LazyLock<MetricDescriptor> = LazyLock::new(|| {
+    new_gauge_md(
+        MetricName::Custom("disk_used_bytes".to_string()),
+        "Used disk space in bytes",
+        &[SERVER_LABEL, DRIVE_LABEL],
+        MetricSubsystem::new("/node"),
+    )
+});
+
+/// Free disk space in bytes
+pub static NODE_DISK_FREE_BYTES_MD: LazyLock<MetricDescriptor> = LazyLock::new(|| {
+    new_gauge_md(
+        MetricName::Custom("disk_free_bytes".to_string()),
+        "Free disk space in bytes",
+        &[SERVER_LABEL, DRIVE_LABEL],
+        MetricSubsystem::new("/node"),
+    )
+});