feat(inputs.lustre2): Add eviction_count field (#15044)

plugins/inputs/lustre2/README.md

@@ -24,20 +24,25 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   ## An array of /proc globs to search for Lustre stats
   ## If not specified, the default will work on Lustre 2.12.x
   ##
+  # mgs_procfiles = [
+  #   "/sys/fs/lustre/mgs/*/eviction_count",
+  # ]
   # ost_procfiles = [
   #   "/proc/fs/lustre/obdfilter/*/stats",
   #   "/proc/fs/lustre/osd-ldiskfs/*/stats",
   #   "/proc/fs/lustre/obdfilter/*/job_stats",
   #   "/proc/fs/lustre/obdfilter/*/exports/*/stats",
   #   "/proc/fs/lustre/osd-ldiskfs/*/brw_stats",
   #   "/proc/fs/lustre/osd-zfs/*/brw_stats",
+  #   "/sys/fs/lustre/odbfilter/*/eviction_count",
   # ]
   # mds_procfiles = [
   #   "/proc/fs/lustre/mdt/*/md_stats",
   #   "/proc/fs/lustre/mdt/*/job_stats",
   #   "/proc/fs/lustre/mdt/*/exports/*/stats",
   #   "/proc/fs/lustre/osd-ldiskfs/*/brw_stats",
   #   "/proc/fs/lustre/osd-zfs/*/brw_stats",
+  #   "/sys/fs/lustre/mdt/*/eviction_count",
   # ]
 ```
 
@@ -174,6 +179,14 @@ From `/proc/fs/lustre/mdt/*/job_stats`:
     - jobstats_sync
     - jobstats_unlink
 
+From `/proc/fs/lustre/*/*/eviction_count`:
+
+- lustre2
+  - tags:
+    - name
+  - fields:
+    - evictions
+
 ## Troubleshooting
 
 Check for the default or custom procfiles in the proc filesystem, and reference

plugins/inputs/lustre2/lustre2.go

@@ -30,6 +30,7 @@ type tags struct {
 // Lustre proc files can change between versions, so we want to future-proof
 // by letting people choose what to look at.
 type Lustre2 struct {
+	MgsProcfiles []string `toml:"mgs_procfiles"`
 	OstProcfiles []string `toml:"ost_procfiles"`
 	MdsProcfiles []string `toml:"mds_procfiles"`
 
@@ -600,6 +601,43 @@ func (l *Lustre2) getLustreProcBrwStats(fileglob string, wantedFields []*mapping
 	return nil
 }
 
+func (l *Lustre2) getLustreEvictionCount(fileglob string) error {
+	files, err := filepath.Glob(filepath.Join(l.rootdir, fileglob))
+	if err != nil {
+		return fmt.Errorf("failed to find files matching glob %s: %w", fileglob, err)
+	}
+
+	for _, file := range files {
+		// Turn /sys/fs/lustre/*/<mgt/mdt/ost_name>/eviction_count into just the object store target name
+		// This assumes that the target name is always second to last, which is true in Lustre 2.1->2.12
+		path := strings.Split(file, "/")
+		if len(path) < 2 {
+			continue
+		}
+		name := path[len(path)-2]
+
+		contents, err := os.ReadFile(file)
+		if err != nil {
+			return fmt.Errorf("failed to read file %s: %w", file, err)
+		}
+
+		value, err := strconv.ParseUint(strings.TrimSpace(string(contents)), 10, 64)
+		if err != nil {
+			return fmt.Errorf("failed to parse file %s: %w", file, err)
+		}
+
+		tag := tags{name, "", "", "", ""}
+		fields, ok := l.allFields[tag]
+		if !ok {
+			fields = make(map[string]interface{})
+			l.allFields[tag] = fields
+		}
+
+		fields["evictions"] = value
+	}
+	return nil
+}
+
 // Gather reads stats from all lustre targets
 func (l *Lustre2) Gather(acc telegraf.Accumulator) error {
 	l.allFields = make(map[tags]map[string]interface{})
@@ -609,6 +647,13 @@ func (l *Lustre2) Gather(acc telegraf.Accumulator) error {
 		return err
 	}
 
+	if len(l.MgsProcfiles) == 0 {
+		l.MgsProcfiles = []string{
+			// eviction count
+			"/sys/fs/lustre/mgs/*/eviction_count",
+		}
+	}
+
 	if len(l.OstProcfiles) == 0 {
 		l.OstProcfiles = []string{
 			// read/write bytes are in obdfilter/<ost_name>/stats
@@ -621,6 +666,8 @@ func (l *Lustre2) Gather(acc telegraf.Accumulator) error {
 			"/proc/fs/lustre/osd-ldiskfs/*/brw_stats",
 			// bulk read/write statistics for zfs
 			"/proc/fs/lustre/osd-zfs/*/brw_stats",
+			// eviction count
+			"/sys/fs/lustre/obdfilter/*/eviction_count",
 		}
 	}
 
@@ -630,9 +677,20 @@ func (l *Lustre2) Gather(acc telegraf.Accumulator) error {
 			"/proc/fs/lustre/mdt/*/md_stats",
 			// Metadata target job stats
 			"/proc/fs/lustre/mdt/*/job_stats",
+			// eviction count
+			"/sys/fs/lustre/mdt/*/eviction_count",
 		}
 	}
 
+	for _, procfile := range l.MgsProcfiles {
+		if !strings.HasSuffix(procfile, "eviction_count") {
+			return fmt.Errorf("no handler found for mgs procfile pattern \"%s\"", procfile)
+		}
+		err := l.getLustreEvictionCount(procfile)
+		if err != nil {
+			return err
+		}
+	}
 	for _, procfile := range l.OstProcfiles {
 		if strings.HasSuffix(procfile, "brw_stats") {
 			err := l.getLustreProcBrwStats(procfile, wantedBrwstatsFields)
@@ -644,6 +702,11 @@ func (l *Lustre2) Gather(acc telegraf.Accumulator) error {
 			if err != nil {
 				return err
 			}
+		} else if strings.HasSuffix(procfile, "eviction_count") {
+			err := l.getLustreEvictionCount(procfile)
+			if err != nil {
+				return err
+			}
 		} else {
 			err := l.GetLustreProcStats(procfile, wantedOstFields)
 			if err != nil {
@@ -662,6 +725,11 @@ func (l *Lustre2) Gather(acc telegraf.Accumulator) error {
 			if err != nil {
 				return err
 			}
+		} else if strings.HasSuffix(procfile, "eviction_count") {
+			err := l.getLustreEvictionCount(procfile)
+			if err != nil {
+				return err
+			}
 		} else {
 			err := l.GetLustreProcStats(procfile, wantedMdsFields)
 			if err != nil {

plugins/inputs/lustre2/lustre2_test.go

@@ -3,7 +3,9 @@
 package lustre2
 
 import (
+	"fmt"
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/influxdata/toml"
@@ -570,3 +572,46 @@ func TestLustre2GeneratesBrwstatsMetrics(t *testing.T) {
 		}
 	}
 }
+
+func TestLustre2GeneratesEvictionMetrics(t *testing.T) {
+	rootdir, err := os.MkdirTemp("", "telegraf-lustre-evictions")
+	require.NoError(t, err)
+	defer os.RemoveAll(rootdir)
+
+	// setup files in mock sysfs
+	type fileEntry struct {
+		targetType string
+		targetName string
+		value      uint64
+	}
+	fileEntries := []fileEntry{
+		{"mdt", "fs-MDT0000", 101},
+		{"mgs", "MGS", 202},
+		{"obdfilter", "fs-OST0001", 303},
+	}
+	for _, f := range fileEntries {
+		d := filepath.Join(rootdir, "sys", "fs", "lustre", f.targetType, f.targetName)
+		err := os.MkdirAll(d, 0750)
+		require.NoError(t, err)
+		err = os.WriteFile(filepath.Join(d, "eviction_count"), []byte(fmt.Sprintf("%d\n", f.value)), 0640)
+		require.NoError(t, err)
+	}
+
+	// gather metrics
+	m := &Lustre2{rootdir: rootdir}
+	var acc testutil.Accumulator
+	err = m.Gather(&acc)
+	require.NoError(t, err)
+
+	// compare with expectations
+	for _, f := range fileEntries {
+		acc.AssertContainsTaggedFields(
+			t,
+			"lustre2",
+			map[string]interface{}{
+				"evictions": f.value,
+			},
+			map[string]string{"name": f.targetName},
+		)
+	}
+}

plugins/inputs/lustre2/sample.conf

@@ -4,18 +4,23 @@
   ## An array of /proc globs to search for Lustre stats
   ## If not specified, the default will work on Lustre 2.12.x
   ##
+  # mgs_procfiles = [
+  #   "/sys/fs/lustre/mgs/*/eviction_count",
+  # ]
   # ost_procfiles = [
   #   "/proc/fs/lustre/obdfilter/*/stats",
   #   "/proc/fs/lustre/osd-ldiskfs/*/stats",
   #   "/proc/fs/lustre/obdfilter/*/job_stats",
   #   "/proc/fs/lustre/obdfilter/*/exports/*/stats",
   #   "/proc/fs/lustre/osd-ldiskfs/*/brw_stats",
   #   "/proc/fs/lustre/osd-zfs/*/brw_stats",
+  #   "/sys/fs/lustre/odbfilter/*/eviction_count",
   # ]
   # mds_procfiles = [
   #   "/proc/fs/lustre/mdt/*/md_stats",
   #   "/proc/fs/lustre/mdt/*/job_stats",
   #   "/proc/fs/lustre/mdt/*/exports/*/stats",
   #   "/proc/fs/lustre/osd-ldiskfs/*/brw_stats",
   #   "/proc/fs/lustre/osd-zfs/*/brw_stats",
+  #   "/sys/fs/lustre/mdt/*/eviction_count",
   # ]