chore: go mod tidy / vendor / make deps

vendor/github.com/prometheus/common/expfmt/decode.go

@@ -70,19 +70,34 @@ func ResponseFormat(h http.Header) Format {
 	return FmtUnknown
 }
 
-// NewDecoder returns a new decoder based on the given input format.
-// If the input format does not imply otherwise, a text format decoder is returned.
+// NewDecoder returns a new decoder based on the given input format. Metric
+// names are validated based on the provided Format -- if the format requires
+// escaping, raditional Prometheues validity checking is used. Otherwise, names
+// are checked for UTF-8 validity. Supported formats include delimited protobuf
+// and Prometheus text format.  For historical reasons, this decoder fallbacks
+// to classic text decoding for any other format. This decoder does not fully
+// support OpenMetrics although it may often succeed due to the similarities
+// between the formats. This decoder may not support the latest features of
+// Prometheus text format and is not intended for high-performance applications.
+// See: https://github.com/prometheus/common/issues/812
 func NewDecoder(r io.Reader, format Format) Decoder {
+	scheme := model.LegacyValidation
+	if format.ToEscapingScheme() == model.NoEscaping {
+		scheme = model.UTF8Validation
+	}
 	switch format.FormatType() {
 	case TypeProtoDelim:
-		return &protoDecoder{r: bufio.NewReader(r)}
+		return &protoDecoder{r: bufio.NewReader(r), s: scheme}
+	case TypeProtoText, TypeProtoCompact:
+		return &errDecoder{err: fmt.Errorf("format %s not supported for decoding", format)}
 	}
-	return &textDecoder{r: r}
+	return &textDecoder{r: r, s: scheme}
 }
 
 // protoDecoder implements the Decoder interface for protocol buffers.
 type protoDecoder struct {
 	r protodelim.Reader
+	s model.ValidationScheme
 }
 
 // Decode implements the Decoder interface.
@@ -93,7 +108,7 @@ func (d *protoDecoder) Decode(v *dto.MetricFamily) error {
 	if err := opts.UnmarshalFrom(d.r, v); err != nil {
 		return err
 	}
-	if !model.IsValidMetricName(model.LabelValue(v.GetName())) {
+	if !d.s.IsValidMetricName(v.GetName()) {
 		return fmt.Errorf("invalid metric name %q", v.GetName())
 	}
 	for _, m := range v.GetMetric() {
@@ -107,7 +122,7 @@ func (d *protoDecoder) Decode(v *dto.MetricFamily) error {
 			if !model.LabelValue(l.GetValue()).IsValid() {
 				return fmt.Errorf("invalid label value %q", l.GetValue())
 			}
-			if !model.LabelName(l.GetName()).IsValid() {
+			if !d.s.IsValidLabelName(l.GetName()) {
 				return fmt.Errorf("invalid label name %q", l.GetName())
 			}
 		}
@@ -115,10 +130,20 @@ func (d *protoDecoder) Decode(v *dto.MetricFamily) error {
 	return nil
 }
 
+// errDecoder is an error-state decoder that always returns the same error.
+type errDecoder struct {
+	err error
+}
+
+func (d *errDecoder) Decode(*dto.MetricFamily) error {
+	return d.err
+}
+
 // textDecoder implements the Decoder interface for the text protocol.
 type textDecoder struct {
 	r    io.Reader
 	fams map[string]*dto.MetricFamily
+	s    model.ValidationScheme
 	err  error
 }
 
@@ -126,7 +151,7 @@ type textDecoder struct {
 func (d *textDecoder) Decode(v *dto.MetricFamily) error {
 	if d.err == nil {
 		// Read all metrics in one shot.
-		var p TextParser
+		p := NewTextParser(d.s)
 		d.fams, d.err = p.TextToMetricFamilies(d.r)
 		// If we don't get an error, store io.EOF for the end.
 		if d.err == nil {

vendor/github.com/prometheus/common/expfmt/encode.go

@@ -18,14 +18,12 @@ import (
 	"io"
 	"net/http"
 
+	"github.com/munnerz/goautoneg"
+	dto "github.com/prometheus/client_model/go"
 	"google.golang.org/protobuf/encoding/protodelim"
 	"google.golang.org/protobuf/encoding/prototext"
 
 	"github.com/prometheus/common/model"
-
-	"github.com/munnerz/goautoneg"
-
-	dto "github.com/prometheus/client_model/go"
 )
 
 // Encoder types encode metric families into an underlying wire protocol.
@@ -61,7 +59,7 @@ func (ec encoderCloser) Close() error {
 // appropriate accepted type is found, FmtText is returned (which is the
 // Prometheus text format). This function will never negotiate FmtOpenMetrics,
 // as the support is still experimental. To include the option to negotiate
-// FmtOpenMetrics, use NegotiateOpenMetrics.
+// FmtOpenMetrics, use NegotiateIncludingOpenMetrics.
 func Negotiate(h http.Header) Format {
 	escapingScheme := Format(fmt.Sprintf("; escaping=%s", Format(model.NameEscapingScheme.String())))
 	for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
@@ -153,7 +151,7 @@ func NewEncoder(w io.Writer, format Format, options ...EncoderOption) Encoder {
 	case TypeProtoDelim:
 		return encoderCloser{
 			encode: func(v *dto.MetricFamily) error {
-				_, err := protodelim.MarshalTo(w, v)
+				_, err := protodelim.MarshalTo(w, model.EscapeMetricFamily(v, escapingScheme))
 				return err
 			},
 			close: func() error { return nil },

vendor/github.com/prometheus/common/expfmt/expfmt.go

@@ -36,9 +36,11 @@ const (
 	ProtoType     = `application/vnd.google.protobuf`
 	ProtoProtocol = `io.prometheus.client.MetricFamily`
 	// Deprecated: Use expfmt.NewFormat(expfmt.TypeProtoCompact) instead.
-	ProtoFmt                 = ProtoType + "; proto=" + ProtoProtocol + ";"
-	OpenMetricsType          = `application/openmetrics-text`
+	ProtoFmt        = ProtoType + "; proto=" + ProtoProtocol + ";"
+	OpenMetricsType = `application/openmetrics-text`
+	//nolint:revive // Allow for underscores.
 	OpenMetricsVersion_0_0_1 = "0.0.1"
+	//nolint:revive // Allow for underscores.
 	OpenMetricsVersion_1_0_0 = "1.0.0"
 
 	// The Content-Type values for the different wire protocols. Do not do direct
@@ -54,8 +56,10 @@ const (
 	// Deprecated: Use expfmt.NewFormat(expfmt.TypeProtoCompact) instead.
 	FmtProtoCompact Format = ProtoFmt + ` encoding=compact-text`
 	// Deprecated: Use expfmt.NewFormat(expfmt.TypeOpenMetrics) instead.
+	//nolint:revive // Allow for underscores.
 	FmtOpenMetrics_1_0_0 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_1_0_0 + `; charset=utf-8`
 	// Deprecated: Use expfmt.NewFormat(expfmt.TypeOpenMetrics) instead.
+	//nolint:revive // Allow for underscores.
 	FmtOpenMetrics_0_0_1 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_0_0_1 + `; charset=utf-8`
 )
 
@@ -188,8 +192,8 @@ func (f Format) FormatType() FormatType {
 // Format contains a escaping=allow-utf-8 term, it will select NoEscaping. If a valid
 // "escaping" term exists, that will be used. Otherwise, the global default will
 // be returned.
-func (format Format) ToEscapingScheme() model.EscapingScheme {
-	for _, p := range strings.Split(string(format), ";") {
+func (f Format) ToEscapingScheme() model.EscapingScheme {
+	for _, p := range strings.Split(string(f), ";") {
 		toks := strings.Split(p, "=")
 		if len(toks) != 2 {
 			continue

vendor/github.com/prometheus/common/expfmt/fuzz.go

@@ -17,7 +17,11 @@
 
 package expfmt
 
-import "bytes"
+import (
+	"bytes"
+
+	"github.com/prometheus/common/model"
+)
 
 // Fuzz text metric parser with with github.com/dvyukov/go-fuzz:
 //
@@ -26,9 +30,8 @@ import "bytes"
 //
 // Further input samples should go in the folder fuzz/corpus.
 func Fuzz(in []byte) int {
-	parser := TextParser{}
+	parser := NewTextParser(model.UTF8Validation)
 	_, err := parser.TextToMetricFamilies(bytes.NewReader(in))
-
 	if err != nil {
 		return 0
 	}

vendor/github.com/prometheus/common/expfmt/openmetrics_create.go

@@ -22,11 +22,10 @@ import (
 	"strconv"
 	"strings"
 
+	dto "github.com/prometheus/client_model/go"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
 	"github.com/prometheus/common/model"
-
-	dto "github.com/prometheus/client_model/go"
 )
 
 type encoderOption struct {
@@ -249,7 +248,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily, options ...E
 
 	// Finally the samples, one line for each.
 	if metricType == dto.MetricType_COUNTER && strings.HasSuffix(name, "_total") {
-		compliantName = compliantName + "_total"
+		compliantName += "_total"
 	}
 	for _, metric := range in.Metric {
 		switch metricType {
@@ -477,7 +476,7 @@ func writeOpenMetricsNameAndLabelPairs(
 	if name != "" {
 		// If the name does not pass the legacy validity check, we must put the
 		// metric name inside the braces, quoted.
-		if !model.IsValidLegacyMetricName(name) {
+		if !model.LegacyValidation.IsValidMetricName(name) {
 			metricInsideBraces = true
 			err := w.WriteByte(separator)
 			written++
@@ -641,11 +640,11 @@ func writeExemplar(w enhancedWriter, e *dto.Exemplar) (int, error) {
 		if err != nil {
 			return written, err
 		}
-		err = (*e).Timestamp.CheckValid()
+		err = e.Timestamp.CheckValid()
 		if err != nil {
 			return written, err
 		}
-		ts := (*e).Timestamp.AsTime()
+		ts := e.Timestamp.AsTime()
 		// TODO(beorn7): Format this directly from components of ts to
 		// avoid overflow/underflow and precision issues of the float
 		// conversion.

vendor/github.com/prometheus/common/expfmt/text_create.go

@@ -22,9 +22,9 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/prometheus/common/model"
-
 	dto "github.com/prometheus/client_model/go"
+
+	"github.com/prometheus/common/model"
 )
 
 // enhancedWriter has all the enhanced write functions needed here. bufio.Writer
@@ -354,7 +354,7 @@ func writeNameAndLabelPairs(
 	if name != "" {
 		// If the name does not pass the legacy validity check, we must put the
 		// metric name inside the braces.
-		if !model.IsValidLegacyMetricName(name) {
+		if !model.LegacyValidation.IsValidMetricName(name) {
 			metricInsideBraces = true
 			err := w.WriteByte(separator)
 			written++
@@ -498,7 +498,7 @@ func writeInt(w enhancedWriter, i int64) (int, error) {
 // writeName writes a string as-is if it complies with the legacy naming
 // scheme, or escapes it in double quotes if not.
 func writeName(w enhancedWriter, name string) (int, error) {
-	if model.IsValidLegacyMetricName(name) {
+	if model.LegacyValidation.IsValidMetricName(name) {
 		return w.WriteString(name)
 	}
 	var written int

vendor/github.com/prometheus/common/expfmt/text_parse.go

@@ -78,6 +78,14 @@ type TextParser struct {
 	// These indicate if the metric name from the current line being parsed is inside
 	// braces and if that metric name was found respectively.
 	currentMetricIsInsideBraces, currentMetricInsideBracesIsPresent bool
+	// scheme sets the desired ValidationScheme for names. Defaults to the invalid
+	// UnsetValidation.
+	scheme model.ValidationScheme
+}
+
+// NewTextParser returns a new TextParser with the provided nameValidationScheme.
+func NewTextParser(nameValidationScheme model.ValidationScheme) TextParser {
+	return TextParser{scheme: nameValidationScheme}
 }
 
 // TextToMetricFamilies reads 'in' as the simple and flat text-based exchange
@@ -126,6 +134,7 @@ func (p *TextParser) TextToMetricFamilies(in io.Reader) (map[string]*dto.MetricF
 
 func (p *TextParser) reset(in io.Reader) {
 	p.metricFamiliesByName = map[string]*dto.MetricFamily{}
+	p.currentLabelPairs = nil
 	if p.buf == nil {
 		p.buf = bufio.NewReader(in)
 	} else {
@@ -216,6 +225,9 @@ func (p *TextParser) startComment() stateFn {
 		return nil
 	}
 	p.setOrCreateCurrentMF()
+	if p.err != nil {
+		return nil
+	}
 	if p.skipBlankTab(); p.err != nil {
 		return nil // Unexpected end of input.
 	}
@@ -244,6 +256,9 @@ func (p *TextParser) readingMetricName() stateFn {
 		return nil
 	}
 	p.setOrCreateCurrentMF()
+	if p.err != nil {
+		return nil
+	}
 	// Now is the time to fix the type if it hasn't happened yet.
 	if p.currentMF.Type == nil {
 		p.currentMF.Type = dto.MetricType_UNTYPED.Enum()
@@ -311,6 +326,9 @@ func (p *TextParser) startLabelName() stateFn {
 			switch p.currentByte {
 			case ',':
 				p.setOrCreateCurrentMF()
+				if p.err != nil {
+					return nil
+				}
 				if p.currentMF.Type == nil {
 					p.currentMF.Type = dto.MetricType_UNTYPED.Enum()
 				}
@@ -319,6 +337,10 @@ func (p *TextParser) startLabelName() stateFn {
 				return p.startLabelName
 			case '}':
 				p.setOrCreateCurrentMF()
+				if p.err != nil {
+					p.currentLabelPairs = nil
+					return nil
+				}
 				if p.currentMF.Type == nil {
 					p.currentMF.Type = dto.MetricType_UNTYPED.Enum()
 				}
@@ -341,6 +363,12 @@ func (p *TextParser) startLabelName() stateFn {
 	p.currentLabelPair = &dto.LabelPair{Name: proto.String(p.currentToken.String())}
 	if p.currentLabelPair.GetName() == string(model.MetricNameLabel) {
 		p.parseError(fmt.Sprintf("label name %q is reserved", model.MetricNameLabel))
+		p.currentLabelPairs = nil
+		return nil
+	}
+	if !p.scheme.IsValidLabelName(p.currentLabelPair.GetName()) {
+		p.parseError(fmt.Sprintf("invalid label name %q", p.currentLabelPair.GetName()))
+		p.currentLabelPairs = nil
 		return nil
 	}
 	// Special summary/histogram treatment. Don't add 'quantile' and 'le'
@@ -353,13 +381,12 @@ func (p *TextParser) startLabelName() stateFn {
 	labels := make(map[string]struct{})
 	for _, l := range p.currentLabelPairs {
 		lName := l.GetName()
-		if _, exists := labels[lName]; !exists {
-			labels[lName] = struct{}{}
-		} else {
+		if _, exists := labels[lName]; exists {
 			p.parseError(fmt.Sprintf("duplicate label names for metric %q", p.currentMF.GetName()))
 			p.currentLabelPairs = nil
 			return nil
 		}
+		labels[lName] = struct{}{}
 	}
 	return p.startLabelValue
 }
@@ -440,7 +467,8 @@ func (p *TextParser) readingValue() stateFn {
 	// When we are here, we have read all the labels, so for the
 	// special case of a summary/histogram, we can finally find out
 	// if the metric already exists.
-	if p.currentMF.GetType() == dto.MetricType_SUMMARY {
+	switch p.currentMF.GetType() {
+	case dto.MetricType_SUMMARY:
 		signature := model.LabelsToSignature(p.currentLabels)
 		if summary := p.summaries[signature]; summary != nil {
 			p.currentMetric = summary
@@ -448,7 +476,7 @@ func (p *TextParser) readingValue() stateFn {
 			p.summaries[signature] = p.currentMetric
 			p.currentMF.Metric = append(p.currentMF.Metric, p.currentMetric)
 		}
-	} else if p.currentMF.GetType() == dto.MetricType_HISTOGRAM {
+	case dto.MetricType_HISTOGRAM:
 		signature := model.LabelsToSignature(p.currentLabels)
 		if histogram := p.histograms[signature]; histogram != nil {
 			p.currentMetric = histogram
@@ -456,7 +484,7 @@ func (p *TextParser) readingValue() stateFn {
 			p.histograms[signature] = p.currentMetric
 			p.currentMF.Metric = append(p.currentMF.Metric, p.currentMetric)
 		}
-	} else {
+	default:
 		p.currentMF.Metric = append(p.currentMF.Metric, p.currentMetric)
 	}
 	if p.readTokenUntilWhitespace(); p.err != nil {
@@ -805,6 +833,10 @@ func (p *TextParser) setOrCreateCurrentMF() {
 	p.currentIsHistogramCount = false
 	p.currentIsHistogramSum = false
 	name := p.currentToken.String()
+	if !p.scheme.IsValidMetricName(name) {
+		p.parseError(fmt.Sprintf("invalid metric name %q", name))
+		return
+	}
 	if p.currentMF = p.metricFamiliesByName[name]; p.currentMF != nil {
 		return
 	}

vendor/github.com/prometheus/common/model/labels.go

@@ -32,6 +32,12 @@ const (
 	// MetricNameLabel is the label name indicating the metric name of a
 	// timeseries.
 	MetricNameLabel = "__name__"
+	// MetricTypeLabel is the label name indicating the metric type of
+	// timeseries as per the PROM-39 proposal.
+	MetricTypeLabel = "__type__"
+	// MetricUnitLabel is the label name indicating the metric unit of
+	// timeseries as per the PROM-39 proposal.
+	MetricUnitLabel = "__unit__"
 
 	// SchemeLabel is the name of the label that holds the scheme on which to
 	// scrape a target.
@@ -100,34 +106,21 @@ type LabelName string
 // IsValid returns true iff the name matches the pattern of LabelNameRE when
 // NameValidationScheme is set to LegacyValidation, or valid UTF-8 if
 // NameValidationScheme is set to UTF8Validation.
+//
+// Deprecated: This method should not be used and may be removed in the future.
+// Use [ValidationScheme.IsValidLabelName] instead.
 func (ln LabelName) IsValid() bool {
-	if len(ln) == 0 {
-		return false
-	}
-	switch NameValidationScheme {
-	case LegacyValidation:
-		return ln.IsValidLegacy()
-	case UTF8Validation:
-		return utf8.ValidString(string(ln))
-	default:
-		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
-	}
+	return NameValidationScheme.IsValidLabelName(string(ln))
 }
 
 // IsValidLegacy returns true iff name matches the pattern of LabelNameRE for
 // legacy names. It does not use LabelNameRE for the check but a much faster
 // hardcoded implementation.
+//
+// Deprecated: This method should not be used and may be removed in the future.
+// Use [LegacyValidation.IsValidLabelName] instead.
 func (ln LabelName) IsValidLegacy() bool {
-	if len(ln) == 0 {
-		return false
-	}
-	for i, b := range ln {
-		// TODO: Apply De Morgan's law. Make sure there are tests for this.
-		if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) { //nolint:staticcheck
-			return false
-		}
-	}
-	return true
+	return LegacyValidation.IsValidLabelName(string(ln))
 }
 
 // UnmarshalYAML implements the yaml.Unmarshaler interface.

vendor/github.com/prometheus/common/model/labelset.go

@@ -114,10 +114,10 @@ func (ls LabelSet) Clone() LabelSet {
 }
 
 // Merge is a helper function to non-destructively merge two label sets.
-func (l LabelSet) Merge(other LabelSet) LabelSet {
-	result := make(LabelSet, len(l))
+func (ls LabelSet) Merge(other LabelSet) LabelSet {
+	result := make(LabelSet, len(ls))
 
-	for k, v := range l {
+	for k, v := range ls {
 		result[k] = v
 	}
 
@@ -140,7 +140,7 @@ func (ls LabelSet) FastFingerprint() Fingerprint {
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface.
-func (l *LabelSet) UnmarshalJSON(b []byte) error {
+func (ls *LabelSet) UnmarshalJSON(b []byte) error {
 	var m map[LabelName]LabelValue
 	if err := json.Unmarshal(b, &m); err != nil {
 		return err
@@ -153,6 +153,6 @@ func (l *LabelSet) UnmarshalJSON(b []byte) error {
 			return fmt.Errorf("%q is not a valid label name", ln)
 		}
 	}
-	*l = LabelSet(m)
+	*ls = LabelSet(m)
 	return nil
 }

vendor/github.com/prometheus/common/model/metric.go

@@ -14,6 +14,7 @@
 package model
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"regexp"
@@ -23,6 +24,7 @@ import (
 	"unicode/utf8"
 
 	dto "github.com/prometheus/client_model/go"
+	"go.yaml.in/yaml/v2"
 	"google.golang.org/protobuf/proto"
 )
 
@@ -62,16 +64,151 @@ var (
 type ValidationScheme int
 
 const (
+	// UnsetValidation represents an undefined ValidationScheme.
+	// Should not be used in practice.
+	UnsetValidation ValidationScheme = iota
+
 	// LegacyValidation is a setting that requires that all metric and label names
 	// conform to the original Prometheus character requirements described by
 	// MetricNameRE and LabelNameRE.
-	LegacyValidation ValidationScheme = iota
+	LegacyValidation
 
 	// UTF8Validation only requires that metric and label names be valid UTF-8
 	// strings.
 	UTF8Validation
 )
 
+var _ interface {
+	yaml.Marshaler
+	yaml.Unmarshaler
+	json.Marshaler
+	json.Unmarshaler
+	fmt.Stringer
+} = new(ValidationScheme)
+
+// String returns the string representation of s.
+func (s ValidationScheme) String() string {
+	switch s {
+	case UnsetValidation:
+		return "unset"
+	case LegacyValidation:
+		return "legacy"
+	case UTF8Validation:
+		return "utf8"
+	default:
+		panic(fmt.Errorf("unhandled ValidationScheme: %d", s))
+	}
+}
+
+// MarshalYAML implements the yaml.Marshaler interface.
+func (s ValidationScheme) MarshalYAML() (any, error) {
+	switch s {
+	case UnsetValidation:
+		return "", nil
+	case LegacyValidation, UTF8Validation:
+		return s.String(), nil
+	default:
+		panic(fmt.Errorf("unhandled ValidationScheme: %d", s))
+	}
+}
+
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
+func (s *ValidationScheme) UnmarshalYAML(unmarshal func(any) error) error {
+	var scheme string
+	if err := unmarshal(&scheme); err != nil {
+		return err
+	}
+	return s.Set(scheme)
+}
+
+// MarshalJSON implements the json.Marshaler interface.
+func (s ValidationScheme) MarshalJSON() ([]byte, error) {
+	switch s {
+	case UnsetValidation:
+		return json.Marshal("")
+	case UTF8Validation, LegacyValidation:
+		return json.Marshal(s.String())
+	default:
+		return nil, fmt.Errorf("unhandled ValidationScheme: %d", s)
+	}
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+func (s *ValidationScheme) UnmarshalJSON(bytes []byte) error {
+	var repr string
+	if err := json.Unmarshal(bytes, &repr); err != nil {
+		return err
+	}
+	return s.Set(repr)
+}
+
+// Set implements the pflag.Value interface.
+func (s *ValidationScheme) Set(text string) error {
+	switch text {
+	case "":
+		// Don't change the value.
+	case LegacyValidation.String():
+		*s = LegacyValidation
+	case UTF8Validation.String():
+		*s = UTF8Validation
+	default:
+		return fmt.Errorf("unrecognized ValidationScheme: %q", text)
+	}
+	return nil
+}
+
+// IsValidMetricName returns whether metricName is valid according to s.
+func (s ValidationScheme) IsValidMetricName(metricName string) bool {
+	switch s {
+	case LegacyValidation:
+		if len(metricName) == 0 {
+			return false
+		}
+		for i, b := range metricName {
+			if !isValidLegacyRune(b, i) {
+				return false
+			}
+		}
+		return true
+	case UTF8Validation:
+		if len(metricName) == 0 {
+			return false
+		}
+		return utf8.ValidString(metricName)
+	default:
+		panic(fmt.Sprintf("Invalid name validation scheme requested: %s", s.String()))
+	}
+}
+
+// IsValidLabelName returns whether labelName is valid according to s.
+func (s ValidationScheme) IsValidLabelName(labelName string) bool {
+	switch s {
+	case LegacyValidation:
+		if len(labelName) == 0 {
+			return false
+		}
+		for i, b := range labelName {
+			// TODO: Apply De Morgan's law. Make sure there are tests for this.
+			if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) { //nolint:staticcheck
+				return false
+			}
+		}
+		return true
+	case UTF8Validation:
+		if len(labelName) == 0 {
+			return false
+		}
+		return utf8.ValidString(labelName)
+	default:
+		panic(fmt.Sprintf("Invalid name validation scheme requested: %s", s))
+	}
+}
+
+// Type implements the pflag.Value interface.
+func (ValidationScheme) Type() string {
+	return "validationScheme"
+}
+
 type EscapingScheme int
 
 const (
@@ -101,7 +238,7 @@ const (
 	// Accept header, the default NameEscapingScheme will be used.
 	EscapingKey = "escaping"
 
-	// Possible values for Escaping Key:
+	// Possible values for Escaping Key.
 	AllowUTF8         = "allow-utf-8" // No escaping required.
 	EscapeUnderscores = "underscores"
 	EscapeDots        = "dots"
@@ -175,34 +312,22 @@ func (m Metric) FastFingerprint() Fingerprint {
 // IsValidMetricName returns true iff name matches the pattern of MetricNameRE
 // for legacy names, and iff it's valid UTF-8 if the UTF8Validation scheme is
 // selected.
+//
+// Deprecated: This function should not be used and might be removed in the future.
+// Use [ValidationScheme.IsValidMetricName] instead.
 func IsValidMetricName(n LabelValue) bool {
-	switch NameValidationScheme {
-	case LegacyValidation:
-		return IsValidLegacyMetricName(string(n))
-	case UTF8Validation:
-		if len(n) == 0 {
-			return false
-		}
-		return utf8.ValidString(string(n))
-	default:
-		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
-	}
+	return NameValidationScheme.IsValidMetricName(string(n))
 }
 
 // IsValidLegacyMetricName is similar to IsValidMetricName but always uses the
 // legacy validation scheme regardless of the value of NameValidationScheme.
 // This function, however, does not use MetricNameRE for the check but a much
 // faster hardcoded implementation.
+//
+// Deprecated: This function should not be used and might be removed in the future.
+// Use [LegacyValidation.IsValidMetricName] instead.
 func IsValidLegacyMetricName(n string) bool {
-	if len(n) == 0 {
-		return false
-	}
-	for i, b := range n {
-		if !isValidLegacyRune(b, i) {
-			return false
-		}
-	}
-	return true
+	return LegacyValidation.IsValidMetricName(n)
 }
 
 // EscapeMetricFamily escapes the given metric names and labels with the given
@@ -310,13 +435,14 @@ func EscapeName(name string, scheme EscapingScheme) string {
 	case DotsEscaping:
 		// Do not early return for legacy valid names, we still escape underscores.
 		for i, b := range name {
-			if b == '_' {
+			switch {
+			case b == '_':
 				escaped.WriteString("__")
-			} else if b == '.' {
+			case b == '.':
 				escaped.WriteString("_dot_")
-			} else if isValidLegacyRune(b, i) {
+			case isValidLegacyRune(b, i):
 				escaped.WriteRune(b)
-			} else {
+			default:
 				escaped.WriteString("__")
 			}
 		}
@@ -327,13 +453,14 @@ func EscapeName(name string, scheme EscapingScheme) string {
 		}
 		escaped.WriteString("U__")
 		for i, b := range name {
-			if b == '_' {
+			switch {
+			case b == '_':
 				escaped.WriteString("__")
-			} else if isValidLegacyRune(b, i) {
+			case isValidLegacyRune(b, i):
 				escaped.WriteRune(b)
-			} else if !utf8.ValidRune(b) {
+			case !utf8.ValidRune(b):
 				escaped.WriteString("_FFFD_")
-			} else {
+			default:
 				escaped.WriteRune('_')
 				escaped.WriteString(strconv.FormatInt(int64(b), 16))
 				escaped.WriteRune('_')
@@ -345,7 +472,7 @@ func EscapeName(name string, scheme EscapingScheme) string {
 	}
 }
 
-// lower function taken from strconv.atoi
+// lower function taken from strconv.atoi.
 func lower(c byte) byte {
 	return c | ('x' - 'X')
 }
@@ -409,11 +536,12 @@ func UnescapeName(name string, scheme EscapingScheme) string {
 				}
 				r := lower(escapedName[i])
 				utf8Val *= 16
-				if r >= '0' && r <= '9' {
+				switch {
+				case r >= '0' && r <= '9':
 					utf8Val += uint(r) - '0'
-				} else if r >= 'a' && r <= 'f' {
+				case r >= 'a' && r <= 'f':
 					utf8Val += uint(r) - 'a' + 10
-				} else {
+				default:
 					return name
 				}
 				i++

vendor/github.com/prometheus/common/model/time.go

@@ -126,14 +126,14 @@ func (t *Time) UnmarshalJSON(b []byte) error {
 	p := strings.Split(string(b), ".")
 	switch len(p) {
 	case 1:
-		v, err := strconv.ParseInt(string(p[0]), 10, 64)
+		v, err := strconv.ParseInt(p[0], 10, 64)
 		if err != nil {
 			return err
 		}
 		*t = Time(v * second)
 
 	case 2:
-		v, err := strconv.ParseInt(string(p[0]), 10, 64)
+		v, err := strconv.ParseInt(p[0], 10, 64)
 		if err != nil {
 			return err
 		}
@@ -143,7 +143,7 @@ func (t *Time) UnmarshalJSON(b []byte) error {
 		if prec < 0 {
 			p[1] = p[1][:dotPrecision]
 		} else if prec > 0 {
-			p[1] = p[1] + strings.Repeat("0", prec)
+			p[1] += strings.Repeat("0", prec)
 		}
 
 		va, err := strconv.ParseInt(p[1], 10, 32)
@@ -170,15 +170,15 @@ func (t *Time) UnmarshalJSON(b []byte) error {
 // This type should not propagate beyond the scope of input/output processing.
 type Duration time.Duration
 
-// Set implements pflag/flag.Value
+// Set implements pflag/flag.Value.
 func (d *Duration) Set(s string) error {
 	var err error
 	*d, err = ParseDuration(s)
 	return err
 }
 
-// Type implements pflag.Value
-func (d *Duration) Type() string {
+// Type implements pflag.Value.
+func (*Duration) Type() string {
 	return "duration"
 }
 

vendor/github.com/prometheus/common/model/value.go

@@ -191,7 +191,8 @@ func (ss SampleStream) String() string {
 }
 
 func (ss SampleStream) MarshalJSON() ([]byte, error) {
-	if len(ss.Histograms) > 0 && len(ss.Values) > 0 {
+	switch {
+	case len(ss.Histograms) > 0 && len(ss.Values) > 0:
 		v := struct {
 			Metric     Metric                `json:"metric"`
 			Values     []SamplePair          `json:"values"`
@@ -202,7 +203,7 @@ func (ss SampleStream) MarshalJSON() ([]byte, error) {
 			Histograms: ss.Histograms,
 		}
 		return json.Marshal(&v)
-	} else if len(ss.Histograms) > 0 {
+	case len(ss.Histograms) > 0:
 		v := struct {
 			Metric     Metric                `json:"metric"`
 			Histograms []SampleHistogramPair `json:"histograms"`
@@ -211,7 +212,7 @@ func (ss SampleStream) MarshalJSON() ([]byte, error) {
 			Histograms: ss.Histograms,
 		}
 		return json.Marshal(&v)
-	} else {
+	default:
 		v := struct {
 			Metric Metric       `json:"metric"`
 			Values []SamplePair `json:"values"`
@@ -258,7 +259,7 @@ func (s Scalar) String() string {
 // MarshalJSON implements json.Marshaler.
 func (s Scalar) MarshalJSON() ([]byte, error) {
 	v := strconv.FormatFloat(float64(s.Value), 'f', -1, 64)
-	return json.Marshal([...]interface{}{s.Timestamp, string(v)})
+	return json.Marshal([...]interface{}{s.Timestamp, v})
 }
 
 // UnmarshalJSON implements json.Unmarshaler.
@@ -349,9 +350,9 @@ func (m Matrix) Len() int           { return len(m) }
 func (m Matrix) Less(i, j int) bool { return m[i].Metric.Before(m[j].Metric) }
 func (m Matrix) Swap(i, j int)      { m[i], m[j] = m[j], m[i] }
 
-func (mat Matrix) String() string {
-	matCp := make(Matrix, len(mat))
-	copy(matCp, mat)
+func (m Matrix) String() string {
+	matCp := make(Matrix, len(m))
+	copy(matCp, m)
 	sort.Sort(matCp)
 
 	strs := make([]string, len(matCp))

vendor/github.com/prometheus/common/model/value_histogram.go

@@ -86,22 +86,22 @@ func (s *HistogramBucket) Equal(o *HistogramBucket) bool {
 	return s == o || (s.Boundaries == o.Boundaries && s.Lower == o.Lower && s.Upper == o.Upper && s.Count == o.Count)
 }
 
-func (b HistogramBucket) String() string {
+func (s HistogramBucket) String() string {
 	var sb strings.Builder
-	lowerInclusive := b.Boundaries == 1 || b.Boundaries == 3
-	upperInclusive := b.Boundaries == 0 || b.Boundaries == 3
+	lowerInclusive := s.Boundaries == 1 || s.Boundaries == 3
+	upperInclusive := s.Boundaries == 0 || s.Boundaries == 3
 	if lowerInclusive {
 		sb.WriteRune('[')
 	} else {
 		sb.WriteRune('(')
 	}
-	fmt.Fprintf(&sb, "%g,%g", b.Lower, b.Upper)
+	fmt.Fprintf(&sb, "%g,%g", s.Lower, s.Upper)
 	if upperInclusive {
 		sb.WriteRune(']')
 	} else {
 		sb.WriteRune(')')
 	}
-	fmt.Fprintf(&sb, ":%v", b.Count)
+	fmt.Fprintf(&sb, ":%v", s.Count)
 	return sb.String()
 }
 

vendor/github.com/prometheus/common/model/value_type.go

@@ -66,8 +66,8 @@ func (et *ValueType) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
-func (e ValueType) String() string {
-	switch e {
+func (et ValueType) String() string {
+	switch et {
 	case ValNone:
 		return "<ValNone>"
 	case ValScalar: