From f527765193377ddc33e417a876a750453aceac83 Mon Sep 17 00:00:00 2001
From: Daniel Kimsey <dekimsey@protonmail.com>
Date: Sat, 23 Mar 2024 15:28:14 -0500
Subject: [PATCH] zfs: Only attempt to pull mibs from supported Releases

In particular 14.0 changed the way arcstats were listed, but we
previously attempted to grab them all. By adding a bit of a major
release detection we reduce the error noise.

Signed-off-by: Daniel Kimsey <dekimsey@protonmail.com>
---
 collector/uname_bsd.go   | 13 +++++++
 collector/zfs_freebsd.go | 74 ++++++++++++++++++++++++----------------
 2 files changed, 58 insertions(+), 29 deletions(-)

diff --git a/collector/uname_bsd.go b/collector/uname_bsd.go
index fa565a1ccf..7b541209a3 100644
--- a/collector/uname_bsd.go
+++ b/collector/uname_bsd.go
@@ -18,6 +18,7 @@
 package collector
 
 import (
+	"strconv"
 	"strings"
 
 	"golang.org/x/sys/unix"
@@ -61,3 +62,15 @@ func parseHostNameAndDomainName(utsname unix.Utsname) (hostname string, domainna
 	}
 	return hostname, domainname
 }
+
+// getOSReleaseMajorMinor returns the Major.Minor version of the Operating System based on the uname's Release as a floating point number
+// this is intended to assist in detecting OS compatibilty/support
+func getOSReleaseMajorMinor() (float64, error) {
+	u, err := getUname()
+	if err != nil {
+		return 0, err
+	}
+	majorMinor := versionRegex.FindString(u.Release)
+	f, err := strconv.ParseFloat(majorMinor, 64)
+	return f, err
+}
diff --git a/collector/zfs_freebsd.go b/collector/zfs_freebsd.go
index d888c3a724..64d4ccaa2b 100644
--- a/collector/zfs_freebsd.go
+++ b/collector/zfs_freebsd.go
@@ -17,8 +17,9 @@
 package collector
 
 import (
-	"github.com/prometheus/client_golang/prometheus"
 	"log/slog"
+
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 type zfsCollector struct {
@@ -31,7 +32,8 @@ const (
 )
 
 func NewZFSCollector(logger *slog.Logger) (Collector, error) {
-	return &zfsCollector{
+	c := &zfsCollector{
+		// Common ZFS sysctl metrics
 		sysctls: []bsdSysctl{
 			{
 				name:        "abdstats_linear_count_total",
@@ -208,59 +210,73 @@ func NewZFSCollector(logger *slog.Logger) (Collector, error) {
 				dataType:    bsdSysctlTypeUint64,
 				valueType:   prometheus.GaugeValue,
 			},
-			// when FreeBSD 14.0+, `meta/pm/pd` install of `p`.
 			{
-				name:        "arcstats_p_bytes",
-				description: "ZFS ARC MRU target size",
-				mib:         "kstat.zfs.misc.arcstats.p",
+				name:        "arcstats_size_bytes",
+				description: "ZFS ARC size",
+				mib:         "kstat.zfs.misc.arcstats.size",
 				dataType:    bsdSysctlTypeUint64,
 				valueType:   prometheus.GaugeValue,
 			},
 			{
+				name:        "zfetchstats_hits_total",
+				description: "ZFS cache fetch hits",
+				mib:         "kstat.zfs.misc.zfetchstats.hits",
+				dataType:    bsdSysctlTypeUint64,
+				valueType:   prometheus.CounterValue,
+			},
+			{
+				name:        "zfetchstats_misses_total",
+				description: "ZFS cache fetch misses",
+				mib:         "kstat.zfs.misc.zfetchstats.misses",
+				dataType:    bsdSysctlTypeUint64,
+				valueType:   prometheus.CounterValue,
+			},
+		},
+		logger: logger,
+	}
+
+	v, err := getOSReleaseMajorMinor()
+	if err != nil {
+		c.logger.Warn("unable to determine OS release, zfs arcstats metrics may be missing or unsupported", "error", err)
+		return c, nil
+	}
+	// when FreeBSD 14.0+, use `meta/pm/pd` instead of `p`.
+	if v >= 14.0 {
+		c.sysctls = append(c.sysctls,
+			bsdSysctl{
 				name:        "arcstats_meta_bytes",
 				description: "ZFS ARC metadata target frac ",
 				mib:         "kstat.zfs.misc.arcstats.meta",
 				dataType:    bsdSysctlTypeUint64,
 				valueType:   prometheus.GaugeValue,
 			},
-			{
+			bsdSysctl{
 				name:        "arcstats_pd_bytes",
 				description: "ZFS ARC data MRU target frac",
 				mib:         "kstat.zfs.misc.arcstats.pd",
 				dataType:    bsdSysctlTypeUint64,
 				valueType:   prometheus.GaugeValue,
 			},
-			{
+			bsdSysctl{
 				name:        "arcstats_pm_bytes",
 				description: "ZFS ARC meta MRU target frac",
 				mib:         "kstat.zfs.misc.arcstats.pm",
 				dataType:    bsdSysctlTypeUint64,
 				valueType:   prometheus.GaugeValue,
 			},
-			{
-				name:        "arcstats_size_bytes",
-				description: "ZFS ARC size",
-				mib:         "kstat.zfs.misc.arcstats.size",
+		)
+	} else {
+		c.sysctls = append(c.sysctls,
+			bsdSysctl{
+				name:        "arcstats_p_bytes",
+				description: "ZFS ARC MRU target size",
+				mib:         "kstat.zfs.misc.arcstats.p",
 				dataType:    bsdSysctlTypeUint64,
 				valueType:   prometheus.GaugeValue,
 			},
-			{
-				name:        "zfetchstats_hits_total",
-				description: "ZFS cache fetch hits",
-				mib:         "kstat.zfs.misc.zfetchstats.hits",
-				dataType:    bsdSysctlTypeUint64,
-				valueType:   prometheus.CounterValue,
-			},
-			{
-				name:        "zfetchstats_misses_total",
-				description: "ZFS cache fetch misses",
-				mib:         "kstat.zfs.misc.zfetchstats.misses",
-				dataType:    bsdSysctlTypeUint64,
-				valueType:   prometheus.CounterValue,
-			},
-		},
-		logger: logger,
-	}, nil
+		)
+	}
+	return c, nil
 }
 
 func (c *zfsCollector) Update(ch chan<- prometheus.Metric) error {