Add separate metrics for non-numeric fields

README.md

@@ -37,8 +37,11 @@ directly using [Go][golang] or [GoReleaser][goreleaser].
 ## Example metrics
 
 ```
-lvm_pv_info{pv_fmt="lvm2",pv_name="/dev/sda1",pv_uuid="yc1zVe-…"} 1
-lvm_pv_info{pv_fmt="lvm2",pv_name="/dev/sdb1",pv_uuid="WVIH97-…"} 1
+lvm_pv_info{pv_name="/dev/sda1",pv_uuid="yc1zVe-…"} 1
+lvm_pv_info{pv_name="/dev/sdb1",pv_uuid="WVIH97-…"} 1
+
+lvm_pv_fmt{pv_fmt="lvm2",pv_uuid="yc1zVe-…"} 1
+lvm_pv_fmt{pv_fmt="lvm2",pv_uuid="WVIH97-…"} 1
 
 lvm_pv_free_bytes{pv_uuid="WVIH97-…"} 9.14358272e+08
 lvm_pv_free_bytes{pv_uuid="yc1zVe-…"} 1.040187392e+09

collector.go

@@ -25,22 +25,22 @@ func newEmptyCollector() *collector {
 	}
 }
 
-func newCollector() *collector {
+func newCollector(enableLegacyInfoLabels bool) *collector {
 	c := newEmptyCollector()
 
 	for _, i := range allGroups {
-		c.gc = append(c.gc, newGroupCollector(i))
+		c.gc = append(c.gc, newGroupCollector(enableLegacyInfoLabels, i))
 	}
 
 	return c
 }
 
-func newCommandCollector(args []string) *collector {
+func newCommandCollector(enableLegacyInfoLabels bool, args []string) *collector {
 	cmd := lvmreport.NewCommand(args)
 
 	var sfg singleflight.Group
 
-	c := newCollector()
+	c := newCollector(enableLegacyInfoLabels)
 	c.load = func(ctx context.Context) (*lvmreport.ReportData, error) {
 		// Avoid concurrent invocations
 		data, err, _ := sfg.Do("", func() (interface{}, error) {

collector_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"strconv"
 	"testing"
 
 	"github.com/hansmi/prometheus-lvm-exporter/lvmreport"
@@ -72,13 +73,23 @@ func TestCollector(t *testing.T) {
 		{name: "issue30-lockargs"},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
-			c := newCollector()
-			c.load = func(ctx context.Context) (*lvmreport.ReportData, error) {
-				return lvmreport.FromFile(fmt.Sprintf("testdata/%s.json", tc.name))
+			for _, enableLegacyInfoLabels := range []bool{false, true} {
+				expectedName := tc.name
+
+				if enableLegacyInfoLabels {
+					expectedName += "-legacy"
+				}
+
+				t.Run(strconv.FormatBool(enableLegacyInfoLabels), func(t *testing.T) {
+					c := newCollector(enableLegacyInfoLabels)
+					c.load = func(ctx context.Context) (*lvmreport.ReportData, error) {
+						return lvmreport.FromFile(fmt.Sprintf("testdata/%s.json", tc.name))
+					}
+
+					g := goldie.New(t)
+					g.Assert(t, expectedName, gatherAndFormat(t, c))
+				})
 			}
-
-			g := goldie.New(t)
-			g.Assert(t, tc.name, gatherAndFormat(t, c))
 		})
 	}
 }

field.go

@@ -0,0 +1,71 @@
+package main
+
+import "strconv"
+
+type metricValueFunc func(string) (float64, error)
+
+func fromNumeric(value string) (float64, error) {
+	return strconv.ParseFloat(value, 64)
+}
+
+type fieldFlag uint
+
+const (
+	// Whether the field should be included as a label on an info metric.
+	asInfoLabel fieldFlag = 1 << iota
+)
+
+type field interface {
+	Name() string
+	MetricName() string
+	Help() string
+}
+
+// textField is an LVM report field whose value can not be made numeric, e.g.
+// a device name or path.
+type textField struct {
+	fieldName string
+	desc      string
+
+	flags fieldFlag
+
+	metricName string
+}
+
+var _ field = (*textField)(nil)
+
+func (f *textField) Name() string {
+	return f.fieldName
+}
+
+func (f *textField) MetricName() string {
+	return f.metricName
+}
+
+func (f *textField) Help() string {
+	return f.desc
+}
+
+// numericField is an LVM report field whose value is numeric or can be
+// converted to a number.
+type numericField struct {
+	fieldName string
+	desc      string
+
+	metricName  string
+	metricValue metricValueFunc
+}
+
+var _ field = (*numericField)(nil)
+
+func (f *numericField) Name() string {
+	return f.fieldName
+}
+
+func (f *numericField) MetricName() string {
+	return f.metricName
+}
+
+func (f *numericField) Help() string {
+	return f.desc
+}

go.mod

@@ -1,6 +1,6 @@
 module github.com/hansmi/prometheus-lvm-exporter
 
-go 1.22
+go 1.22.0
 
 toolchain go1.22.7
 
@@ -33,6 +33,7 @@ require (
 	github.com/sergi/go-diff v1.2.0 // indirect
 	github.com/xhit/go-str2duration/v2 v2.1.0 // indirect
 	golang.org/x/crypto v0.28.0 // indirect
+	golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f // indirect
 	golang.org/x/net v0.29.0 // indirect
 	golang.org/x/oauth2 v0.23.0 // indirect
 	golang.org/x/sys v0.26.0 // indirect

go.sum

@@ -66,6 +66,8 @@ github.com/xhit/go-str2duration/v2 v2.1.0 h1:lxklc02Drh6ynqX+DdPyp5pCKLUQpRT8bp8
 github.com/xhit/go-str2duration/v2 v2.1.0/go.mod h1:ohY8p+0f07DiV6Em5LKB0s2YpLtXVyJfNt1+BlmyAsU=
 golang.org/x/crypto v0.28.0 h1:GBDwsMXVQi34v5CCYUm2jkJvu4cbtru2U4TN2PSyQnw=
 golang.org/x/crypto v0.28.0/go.mod h1:rmgy+3RHxRZMyY0jjAJShp2zgEdOqj2AO7U0pYmeQ7U=
+golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f h1:XdNn9LlyWAhLVp6P/i8QYBW+hlyhrhei9uErw2B5GJo=
+golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f/go.mod h1:D5SMRVC3C2/4+F/DB1wZsLRnSNimn2Sp/NPsCrsv8ak=
 golang.org/x/net v0.29.0 h1:5ORfpBpCs4HzDYoodCDBbwHzdR5UrLBZ3sOnUJmFoHo=
 golang.org/x/net v0.29.0/go.mod h1:gLkgy8jTGERgjzMic6DS9+SP0ajcu6Xu3Orq/SpETg0=
 golang.org/x/oauth2 v0.23.0 h1:PbgcYx2W7i4LvjJWEbf0ngHV6qJYr86PkAV3bXdLEbs=

group.go

@@ -1,8 +1,6 @@
 package main
 
 import (
-	"slices"
-
 	"github.com/hansmi/prometheus-lvm-exporter/lvmreport"
 )
 
@@ -11,26 +9,14 @@ type group struct {
 
 	infoMetricName string
 
-	keyFields    []*descriptor
-	infoFields   []*descriptor
-	metricFields []*descriptor
-}
-
-func (r *group) allDescriptors() []*descriptor {
-	d := slices.Clone(r.keyFields)
-	d = append(d, r.infoFields...)
-	d = append(d, r.metricFields...)
-	return d
-}
-
-func (r *group) fieldNames() []string {
-	var names []string
+	// Fields applied to all metrics from the group.
+	keyFields []*textField
 
-	for _, d := range r.allDescriptors() {
-		names = append(names, d.fieldName)
-	}
+	// Non-numeric fields, e.g. a device path.
+	textFields []*textField
 
-	return names
+	// Numeric fields, either directly or after conversion.
+	numericFields []*numericField
 }
 
 var allGroups = []*group{pvGroup, vgGroup, lvGroup}