feat(host_metrics source): collect inode metrics

Author: mushrowan

Cargo.toml

@@ -443,7 +443,7 @@ byteorder = "1.5.0"
 windows-service = "0.8.0"
 
 [target.'cfg(unix)'.dependencies]
-nix = { version = "0.26.2", default-features = false, features = ["socket", "signal"] }
+nix = { version = "0.26.2", default-features = false, features = ["socket", "signal", "fs"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 netlink-packet-utils = "0.5.2"

changelog.d/7538_filesystem_inode_metrics.feature.md

@@ -0,0 +1,3 @@
+added inode metrics to the `host_metrics` source filesystem collector on unix systems: `filesystem_inodes_total`, `filesystem_inodes_free`, and `filesystem_inodes_used`.
+
+authors: mushrowan

src/sources/host_metrics/filesystem.rs

@@ -2,6 +2,8 @@ use futures::StreamExt;
 use heim::units::information::byte;
 #[cfg(not(windows))]
 use heim::units::ratio::ratio;
+#[cfg(unix)]
+use nix::sys::statvfs::statvfs;
 use vector_lib::{configurable::configurable_component, metric_tags};
 
 use super::{FilterList, HostMetrics, default_all_devices, example_devices, filter_result};
@@ -128,8 +130,28 @@ impl HostMetrics {
                     output.gauge(
                         "filesystem_used_ratio",
                         usage.ratio().get::<ratio>() as f64,
-                        tags,
+                        tags.clone(),
                     );
+
+                    // Inode metrics (Unix only)
+                    #[cfg(unix)]
+                    if let Ok(stat) = statvfs(partition.mount_point()) {
+                        let inodes_total = stat.files() as f64;
+                        let inodes_free = stat.files_free() as f64;
+                        let inodes_used = inodes_total - inodes_free;
+                        let inodes_used_ratio = if inodes_total > 0.0 {
+                            inodes_used / inodes_total
+                        } else {
+                            0.0
+                        };
+
+                        output.gauge("filesystem_inodes_total", inodes_total, tags.clone());
+                        output.gauge("filesystem_inodes_free", inodes_free, tags.clone());
+                        output.gauge("filesystem_inodes_used", inodes_used, tags.clone());
+                        output.gauge("filesystem_inodes_used_ratio", inodes_used_ratio, tags);
+                    }
+                    #[cfg(windows)]
+                    drop(tags);
                 }
             }
             Err(error) => {
@@ -161,17 +183,40 @@ mod tests {
             .await;
         let metrics = buffer.metrics;
         assert!(!metrics.is_empty());
-        assert!(metrics.len().is_multiple_of(4));
         assert!(all_gauges(&metrics));
 
-        // There are exactly three filesystem_* names
-        for name in &[
+        // Base metrics (these are always present)
+        let base_metrics = [
             "filesystem_free_bytes",
             "filesystem_total_bytes",
             "filesystem_used_bytes",
             "filesystem_used_ratio",
-        ] {
-            assert_eq!(count_name(&metrics, name), metrics.len() / 4, "name={name}");
+        ];
+
+        // Each filesystem should have all 4 base metrics
+        let num_filesystems = count_name(&metrics, "filesystem_free_bytes");
+        assert!(num_filesystems > 0);
+        for name in &base_metrics {
+            assert_eq!(count_name(&metrics, name), num_filesystems, "name={name}");
+        }
+
+        // Inode metrics are present for filesystems that support statvfs
+        // (some virtual filesystems like /proc, /sys might not)
+        let inode_metrics = [
+            "filesystem_inodes_total",
+            "filesystem_inodes_free",
+            "filesystem_inodes_used",
+            "filesystem_inodes_used_ratio",
+        ];
+        let num_inode_total = count_name(&metrics, "filesystem_inodes_total");
+        assert!(
+            num_inode_total > 0,
+            "Expected at least one filesystem to report inode metrics"
+        );
+
+        // For filesystems that report inodes, all 4 inode metrics should be present
+        for name in &inode_metrics {
+            assert_eq!(count_name(&metrics, name), num_inode_total, "name={name}");
         }
 
         // They should all have "filesystem" and "mountpoint" tags