Update go.mod, Alpine to 3.20.0 and to Go 1.22

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alex@openfaas.com>

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

@@ -14,6 +14,7 @@
 package expfmt
 
 import (
+	"bufio"
 	"fmt"
 	"io"
 	"math"
@@ -21,8 +22,8 @@ import (
 	"net/http"
 
 	dto "github.com/prometheus/client_model/go"
+	"google.golang.org/protobuf/encoding/protodelim"
 
-	"github.com/matttproud/golang_protobuf_extensions/pbutil"
 	"github.com/prometheus/common/model"
 )
 
@@ -44,7 +45,7 @@ func ResponseFormat(h http.Header) Format {
 
 	mediatype, params, err := mime.ParseMediaType(ct)
 	if err != nil {
-		return FmtUnknown
+		return fmtUnknown
 	}
 
 	const textType = "text/plain"
@@ -52,42 +53,44 @@ func ResponseFormat(h http.Header) Format {
 	switch mediatype {
 	case ProtoType:
 		if p, ok := params["proto"]; ok && p != ProtoProtocol {
-			return FmtUnknown
+			return fmtUnknown
 		}
 		if e, ok := params["encoding"]; ok && e != "delimited" {
-			return FmtUnknown
+			return fmtUnknown
 		}
-		return FmtProtoDelim
+		return fmtProtoDelim
 
 	case textType:
 		if v, ok := params["version"]; ok && v != TextVersion {
-			return FmtUnknown
+			return fmtUnknown
 		}
-		return FmtText
+		return fmtText
 	}
 
-	return FmtUnknown
+	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.
 func NewDecoder(r io.Reader, format Format) Decoder {
-	switch format {
-	case FmtProtoDelim:
-		return &protoDecoder{r: r}
+	switch format.FormatType() {
+	case TypeProtoDelim:
+		return &protoDecoder{r: bufio.NewReader(r)}
 	}
 	return &textDecoder{r: r}
 }
 
 // protoDecoder implements the Decoder interface for protocol buffers.
 type protoDecoder struct {
-	r io.Reader
+	r protodelim.Reader
 }
 
 // Decode implements the Decoder interface.
 func (d *protoDecoder) Decode(v *dto.MetricFamily) error {
-	_, err := pbutil.ReadDelimited(d.r, v)
-	if err != nil {
+	opts := protodelim.UnmarshalOptions{
+		MaxSize: -1,
+	}
+	if err := opts.UnmarshalFrom(d.r, v); err != nil {
 		return err
 	}
 	if !model.IsValidMetricName(model.LabelValue(v.GetName())) {

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

@@ -18,10 +18,12 @@ import (
 	"io"
 	"net/http"
 
-	"github.com/matttproud/golang_protobuf_extensions/pbutil"
-	"github.com/prometheus/common/internal/bitbucket.org/ww/goautoneg"
+	"google.golang.org/protobuf/encoding/protodelim"
 	"google.golang.org/protobuf/encoding/prototext"
 
+	"github.com/prometheus/common/internal/bitbucket.org/ww/goautoneg"
+	"github.com/prometheus/common/model"
+
 	dto "github.com/prometheus/client_model/go"
 )
 
@@ -60,23 +62,32 @@ func (ec encoderCloser) Close() error {
 // as the support is still experimental. To include the option to negotiate
 // FmtOpenMetrics, use NegotiateOpenMetrics.
 func Negotiate(h http.Header) Format {
+	escapingScheme := Format(fmt.Sprintf("; escaping=%s", Format(model.NameEscapingScheme.String())))
 	for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
+		if escapeParam := ac.Params[model.EscapingKey]; escapeParam != "" {
+			switch Format(escapeParam) {
+			case model.AllowUTF8, model.EscapeUnderscores, model.EscapeDots, model.EscapeValues:
+				escapingScheme = Format(fmt.Sprintf("; escaping=%s", escapeParam))
+			default:
+				// If the escaping parameter is unknown, ignore it.
+			}
+		}
 		ver := ac.Params["version"]
 		if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
 			switch ac.Params["encoding"] {
 			case "delimited":
-				return FmtProtoDelim
+				return fmtProtoDelim + escapingScheme
 			case "text":
-				return FmtProtoText
+				return fmtProtoText + escapingScheme
 			case "compact-text":
-				return FmtProtoCompact
+				return fmtProtoCompact + escapingScheme
 			}
 		}
 		if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
-			return FmtText
+			return fmtText + escapingScheme
 		}
 	}
-	return FmtText
+	return fmtText + escapingScheme
 }
 
 // NegotiateIncludingOpenMetrics works like Negotiate but includes
@@ -84,29 +95,40 @@ func Negotiate(h http.Header) Format {
 // temporary and will disappear once FmtOpenMetrics is fully supported and as
 // such may be negotiated by the normal Negotiate function.
 func NegotiateIncludingOpenMetrics(h http.Header) Format {
+	escapingScheme := Format(fmt.Sprintf("; escaping=%s", Format(model.NameEscapingScheme.String())))
 	for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
+		if escapeParam := ac.Params[model.EscapingKey]; escapeParam != "" {
+			switch Format(escapeParam) {
+			case model.AllowUTF8, model.EscapeUnderscores, model.EscapeDots, model.EscapeValues:
+				escapingScheme = Format(fmt.Sprintf("; escaping=%s", escapeParam))
+			default:
+				// If the escaping parameter is unknown, ignore it.
+			}
+		}
 		ver := ac.Params["version"]
 		if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
 			switch ac.Params["encoding"] {
 			case "delimited":
-				return FmtProtoDelim
+				return fmtProtoDelim + escapingScheme
 			case "text":
-				return FmtProtoText
+				return fmtProtoText + escapingScheme
 			case "compact-text":
-				return FmtProtoCompact
+				return fmtProtoCompact + escapingScheme
 			}
 		}
 		if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
-			return FmtText
+			return fmtText + escapingScheme
 		}
 		if ac.Type+"/"+ac.SubType == OpenMetricsType && (ver == OpenMetricsVersion_0_0_1 || ver == OpenMetricsVersion_1_0_0 || ver == "") {
-			if ver == OpenMetricsVersion_1_0_0 {
-				return FmtOpenMetrics_1_0_0
+			switch ver {
+			case OpenMetricsVersion_1_0_0:
+				return fmtOpenMetrics_1_0_0 + escapingScheme
+			default:
+				return fmtOpenMetrics_0_0_1 + escapingScheme
 			}
-			return FmtOpenMetrics_0_0_1
 		}
 	}
-	return FmtText
+	return fmtText + escapingScheme
 }
 
 // NewEncoder returns a new encoder based on content type negotiation. All
@@ -115,44 +137,54 @@ func NegotiateIncludingOpenMetrics(h http.Header) Format {
 // for FmtOpenMetrics, but a future (breaking) release will add the Close method
 // to the Encoder interface directly. The current version of the Encoder
 // interface is kept for backwards compatibility.
-func NewEncoder(w io.Writer, format Format) Encoder {
-	switch format {
-	case FmtProtoDelim:
+// In cases where the Format does not allow for UTF-8 names, the global
+// NameEscapingScheme will be applied.
+//
+// NewEncoder can be called with additional options to customize the OpenMetrics text output.
+// For example:
+// NewEncoder(w, FmtOpenMetrics_1_0_0, WithCreatedLines())
+//
+// Extra options are ignored for all other formats.
+func NewEncoder(w io.Writer, format Format, options ...EncoderOption) Encoder {
+	escapingScheme := format.ToEscapingScheme()
+
+	switch format.FormatType() {
+	case TypeProtoDelim:
 		return encoderCloser{
 			encode: func(v *dto.MetricFamily) error {
-				_, err := pbutil.WriteDelimited(w, v)
+				_, err := protodelim.MarshalTo(w, v)
 				return err
 			},
 			close: func() error { return nil },
 		}
-	case FmtProtoCompact:
+	case TypeProtoCompact:
 		return encoderCloser{
 			encode: func(v *dto.MetricFamily) error {
-				_, err := fmt.Fprintln(w, v.String())
+				_, err := fmt.Fprintln(w, model.EscapeMetricFamily(v, escapingScheme).String())
 				return err
 			},
 			close: func() error { return nil },
 		}
-	case FmtProtoText:
+	case TypeProtoText:
 		return encoderCloser{
 			encode: func(v *dto.MetricFamily) error {
-				_, err := fmt.Fprintln(w, prototext.Format(v))
+				_, err := fmt.Fprintln(w, prototext.Format(model.EscapeMetricFamily(v, escapingScheme)))
 				return err
 			},
 			close: func() error { return nil },
 		}
-	case FmtText:
+	case TypeTextPlain:
 		return encoderCloser{
 			encode: func(v *dto.MetricFamily) error {
-				_, err := MetricFamilyToText(w, v)
+				_, err := MetricFamilyToText(w, model.EscapeMetricFamily(v, escapingScheme))
 				return err
 			},
 			close: func() error { return nil },
 		}
-	case FmtOpenMetrics_0_0_1, FmtOpenMetrics_1_0_0:
+	case TypeOpenMetrics:
 		return encoderCloser{
 			encode: func(v *dto.MetricFamily) error {
-				_, err := MetricFamilyToOpenMetrics(w, v)
+				_, err := MetricFamilyToOpenMetrics(w, model.EscapeMetricFamily(v, escapingScheme), options...)
 				return err
 			},
 			close: func() error {

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

@@ -14,30 +14,164 @@
 // Package expfmt contains tools for reading and writing Prometheus metrics.
 package expfmt
 
+import (
+	"fmt"
+	"strings"
+
+	"github.com/prometheus/common/model"
+)
+
 // Format specifies the HTTP content type of the different wire protocols.
 type Format string
 
-// Constants to assemble the Content-Type values for the different wire protocols.
+// Constants to assemble the Content-Type values for the different wire
+// protocols. The Content-Type strings here are all for the legacy exposition
+// formats, where valid characters for metric names and label names are limited.
+// Support for arbitrary UTF-8 characters in those names is already partially
+// implemented in this module (see model.ValidationScheme), but to actually use
+// it on the wire, new content-type strings will have to be agreed upon and
+// added here.
 const (
 	TextVersion              = "0.0.4"
 	ProtoType                = `application/vnd.google.protobuf`
 	ProtoProtocol            = `io.prometheus.client.MetricFamily`
-	ProtoFmt                 = ProtoType + "; proto=" + ProtoProtocol + ";"
+	protoFmt                 = ProtoType + "; proto=" + ProtoProtocol + ";"
 	OpenMetricsType          = `application/openmetrics-text`
 	OpenMetricsVersion_0_0_1 = "0.0.1"
 	OpenMetricsVersion_1_0_0 = "1.0.0"
 
-	// The Content-Type values for the different wire protocols.
-	FmtUnknown           Format = `<unknown>`
-	FmtText              Format = `text/plain; version=` + TextVersion + `; charset=utf-8`
-	FmtProtoDelim        Format = ProtoFmt + ` encoding=delimited`
-	FmtProtoText         Format = ProtoFmt + ` encoding=text`
-	FmtProtoCompact      Format = ProtoFmt + ` encoding=compact-text`
-	FmtOpenMetrics_1_0_0 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_1_0_0 + `; charset=utf-8`
-	FmtOpenMetrics_0_0_1 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_0_0_1 + `; charset=utf-8`
+	// The Content-Type values for the different wire protocols. Note that these
+	// values are now unexported. If code was relying on comparisons to these
+	// constants, instead use FormatType().
+	fmtUnknown           Format = `<unknown>`
+	fmtText              Format = `text/plain; version=` + TextVersion + `; charset=utf-8`
+	fmtProtoDelim        Format = protoFmt + ` encoding=delimited`
+	fmtProtoText         Format = protoFmt + ` encoding=text`
+	fmtProtoCompact      Format = protoFmt + ` encoding=compact-text`
+	fmtOpenMetrics_1_0_0 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_1_0_0 + `; charset=utf-8`
+	fmtOpenMetrics_0_0_1 Format = OpenMetricsType + `; version=` + OpenMetricsVersion_0_0_1 + `; charset=utf-8`
 )
 
 const (
 	hdrContentType = "Content-Type"
 	hdrAccept      = "Accept"
 )
+
+// FormatType is a Go enum representing the overall category for the given
+// Format. As the number of Format permutations increases, doing basic string
+// comparisons are not feasible, so this enum captures the most useful
+// high-level attribute of the Format string.
+type FormatType int
+
+const (
+	TypeUnknown FormatType = iota
+	TypeProtoCompact
+	TypeProtoDelim
+	TypeProtoText
+	TypeTextPlain
+	TypeOpenMetrics
+)
+
+// NewFormat generates a new Format from the type provided. Mostly used for
+// tests, most Formats should be generated as part of content negotiation in
+// encode.go. If a type has more than one version, the latest version will be
+// returned.
+func NewFormat(t FormatType) Format {
+	switch t {
+	case TypeProtoCompact:
+		return fmtProtoCompact
+	case TypeProtoDelim:
+		return fmtProtoDelim
+	case TypeProtoText:
+		return fmtProtoText
+	case TypeTextPlain:
+		return fmtText
+	case TypeOpenMetrics:
+		return fmtOpenMetrics_1_0_0
+	default:
+		return fmtUnknown
+	}
+}
+
+// NewOpenMetricsFormat generates a new OpenMetrics format matching the
+// specified version number.
+func NewOpenMetricsFormat(version string) (Format, error) {
+	if version == OpenMetricsVersion_0_0_1 {
+		return fmtOpenMetrics_0_0_1, nil
+	}
+	if version == OpenMetricsVersion_1_0_0 {
+		return fmtOpenMetrics_1_0_0, nil
+	}
+	return fmtUnknown, fmt.Errorf("unknown open metrics version string")
+}
+
+// FormatType deduces an overall FormatType for the given format.
+func (f Format) FormatType() FormatType {
+	toks := strings.Split(string(f), ";")
+	params := make(map[string]string)
+	for i, t := range toks {
+		if i == 0 {
+			continue
+		}
+		args := strings.Split(t, "=")
+		if len(args) != 2 {
+			continue
+		}
+		params[strings.TrimSpace(args[0])] = strings.TrimSpace(args[1])
+	}
+
+	switch strings.TrimSpace(toks[0]) {
+	case ProtoType:
+		if params["proto"] != ProtoProtocol {
+			return TypeUnknown
+		}
+		switch params["encoding"] {
+		case "delimited":
+			return TypeProtoDelim
+		case "text":
+			return TypeProtoText
+		case "compact-text":
+			return TypeProtoCompact
+		default:
+			return TypeUnknown
+		}
+	case OpenMetricsType:
+		if params["charset"] != "utf-8" {
+			return TypeUnknown
+		}
+		return TypeOpenMetrics
+	case "text/plain":
+		v, ok := params["version"]
+		if !ok {
+			return TypeTextPlain
+		}
+		if v == TextVersion {
+			return TypeTextPlain
+		}
+		return TypeUnknown
+	default:
+		return TypeUnknown
+	}
+}
+
+// ToEscapingScheme returns an EscapingScheme depending on the Format. Iff the
+// 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), ";") {
+		toks := strings.Split(p, "=")
+		if len(toks) != 2 {
+			continue
+		}
+		key, value := strings.TrimSpace(toks[0]), strings.TrimSpace(toks[1])
+		if key == model.EscapingKey {
+			scheme, err := model.ToEscapingScheme(value)
+			if err != nil {
+				return model.NameEscapingScheme
+			}
+			return scheme
+		}
+	}
+	return model.NameEscapingScheme
+}

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

@@ -22,11 +22,47 @@ import (
 	"strconv"
 	"strings"
 
+	"google.golang.org/protobuf/types/known/timestamppb"
+
 	"github.com/prometheus/common/model"
 
 	dto "github.com/prometheus/client_model/go"
 )
 
+type encoderOption struct {
+	withCreatedLines bool
+	withUnit         bool
+}
+
+type EncoderOption func(*encoderOption)
+
+// WithCreatedLines is an EncoderOption that configures the OpenMetrics encoder
+// to include _created lines (See
+// https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#counter-1).
+// Created timestamps can improve the accuracy of series reset detection, but
+// come with a bandwidth cost.
+//
+// At the time of writing, created timestamp ingestion is still experimental in
+// Prometheus and need to be enabled with the feature-flag
+// `--feature-flag=created-timestamp-zero-ingestion`, and breaking changes are
+// still possible. Therefore, it is recommended to use this feature with caution.
+func WithCreatedLines() EncoderOption {
+	return func(t *encoderOption) {
+		t.withCreatedLines = true
+	}
+}
+
+// WithUnit is an EncoderOption enabling a set unit to be written to the output
+// and to be added to the metric name, if it's not there already, as a suffix.
+// Without opting in this way, the unit will not be added to the metric name and,
+// on top of that, the unit will not be passed onto the output, even if it
+// were declared in the *dto.MetricFamily struct, i.e. even if in.Unit !=nil.
+func WithUnit() EncoderOption {
+	return func(t *encoderOption) {
+		t.withUnit = true
+	}
+}
+
 // MetricFamilyToOpenMetrics converts a MetricFamily proto message into the
 // OpenMetrics text format and writes the resulting lines to 'out'. It returns
 // the number of bytes written and any error encountered. The output will have
@@ -35,6 +71,18 @@ import (
 // sanity checks. If the input contains duplicate metrics or invalid metric or
 // label names, the conversion will result in invalid text format output.
 //
+// If metric names conform to the legacy validation pattern, they will be placed
+// outside the brackets in the traditional way, like `foo{}`. If the metric name
+// fails the legacy validation check, it will be placed quoted inside the
+// brackets: `{"foo"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
+// Similar to metric names, if label names conform to the legacy validation
+// pattern, they will be unquoted as normal, like `foo{bar="baz"}`. If the label
+// name fails the legacy validation check, it will be quoted:
+// `foo{"bar"="baz"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
 // This function fulfills the type 'expfmt.encoder'.
 //
 // Note that OpenMetrics requires a final `# EOF` line. Since this function acts
@@ -47,20 +95,34 @@ import (
 // Prometheus to OpenMetrics or vice versa:
 //
 //   - Counters are expected to have the `_total` suffix in their metric name. In
-//     the output, the suffix will be truncated from the `# TYPE` and `# HELP`
-//     line. A counter with a missing `_total` suffix is not an error. However,
+//     the output, the suffix will be truncated from the `# TYPE`, `# HELP` and `# UNIT`
+//     lines. A counter with a missing `_total` suffix is not an error. However,
 //     its type will be set to `unknown` in that case to avoid invalid OpenMetrics
 //     output.
 //
-//   - No support for the following (optional) features: `# UNIT` line, `_created`
-//     line, info type, stateset type, gaugehistogram type.
+//   - According to the OM specs, the `# UNIT` line is optional, but if populated,
+//     the unit has to be present in the metric name as its suffix:
+//     (see https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#unit).
+//     However, in order to accommodate any potential scenario where such a change in the
+//     metric name is not desirable, the users are here given the choice of either explicitly
+//     opt in, in case they wish for the unit to be included in the output AND in the metric name
+//     as a suffix (see the description of the WithUnit function above),
+//     or not to opt in, in case they don't want for any of that to happen.
+//
+//   - No support for the following (optional) features: info type,
+//     stateset type, gaugehistogram type.
 //
 //   - The size of exemplar labels is not checked (i.e. it's possible to create
 //     exemplars that are larger than allowed by the OpenMetrics specification).
 //
 //   - The value of Counters is not checked. (OpenMetrics doesn't allow counters
 //     with a `NaN` value.)
-func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int, err error) {
+func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily, options ...EncoderOption) (written int, err error) {
+	toOM := encoderOption{}
+	for _, option := range options {
+		option(&toOM)
+	}
+
 	name := in.GetName()
 	if name == "" {
 		return 0, fmt.Errorf("MetricFamily has no name: %s", in)
@@ -83,12 +145,15 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 	}
 
 	var (
-		n          int
-		metricType = in.GetType()
-		shortName  = name
+		n             int
+		metricType    = in.GetType()
+		compliantName = name
 	)
-	if metricType == dto.MetricType_COUNTER && strings.HasSuffix(shortName, "_total") {
-		shortName = name[:len(name)-6]
+	if metricType == dto.MetricType_COUNTER && strings.HasSuffix(compliantName, "_total") {
+		compliantName = name[:len(name)-6]
+	}
+	if toOM.withUnit && in.Unit != nil && !strings.HasSuffix(compliantName, fmt.Sprintf("_%s", *in.Unit)) {
+		compliantName = compliantName + fmt.Sprintf("_%s", *in.Unit)
 	}
 
 	// Comments, first HELP, then TYPE.
@@ -98,7 +163,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 		if err != nil {
 			return
 		}
-		n, err = w.WriteString(shortName)
+		n, err = writeName(w, compliantName)
 		written += n
 		if err != nil {
 			return
@@ -124,7 +189,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 	if err != nil {
 		return
 	}
-	n, err = w.WriteString(shortName)
+	n, err = writeName(w, compliantName)
 	written += n
 	if err != nil {
 		return
@@ -151,55 +216,89 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 	if err != nil {
 		return
 	}
+	if toOM.withUnit && in.Unit != nil {
+		n, err = w.WriteString("# UNIT ")
+		written += n
+		if err != nil {
+			return
+		}
+		n, err = writeName(w, compliantName)
+		written += n
+		if err != nil {
+			return
+		}
+
+		err = w.WriteByte(' ')
+		written++
+		if err != nil {
+			return
+		}
+		n, err = writeEscapedString(w, *in.Unit, true)
+		written += n
+		if err != nil {
+			return
+		}
+		err = w.WriteByte('\n')
+		written++
+		if err != nil {
+			return
+		}
+	}
+
+	var createdTsBytesWritten int
 
 	// Finally the samples, one line for each.
+	if metricType == dto.MetricType_COUNTER && strings.HasSuffix(name, "_total") {
+		compliantName = compliantName + "_total"
+	}
 	for _, metric := range in.Metric {
 		switch metricType {
 		case dto.MetricType_COUNTER:
 			if metric.Counter == nil {
 				return written, fmt.Errorf(
-					"expected counter in metric %s %s", name, metric,
+					"expected counter in metric %s %s", compliantName, metric,
 				)
 			}
-			// Note that we have ensured above that either the name
-			// ends on `_total` or that the rendered type is
-			// `unknown`. Therefore, no `_total` must be added here.
 			n, err = writeOpenMetricsSample(
-				w, name, "", metric, "", 0,
+				w, compliantName, "", metric, "", 0,
 				metric.Counter.GetValue(), 0, false,
 				metric.Counter.Exemplar,
 			)
+			if toOM.withCreatedLines && metric.Counter.CreatedTimestamp != nil {
+				createdTsBytesWritten, err = writeOpenMetricsCreated(w, compliantName, "_total", metric, "", 0, metric.Counter.GetCreatedTimestamp())
+				n += createdTsBytesWritten
+			}
 		case dto.MetricType_GAUGE:
 			if metric.Gauge == nil {
 				return written, fmt.Errorf(
-					"expected gauge in metric %s %s", name, metric,
+					"expected gauge in metric %s %s", compliantName, metric,
 				)
 			}
 			n, err = writeOpenMetricsSample(
-				w, name, "", metric, "", 0,
+				w, compliantName, "", metric, "", 0,
 				metric.Gauge.GetValue(), 0, false,
 				nil,
 			)
 		case dto.MetricType_UNTYPED:
 			if metric.Untyped == nil {
 				return written, fmt.Errorf(
-					"expected untyped in metric %s %s", name, metric,
+					"expected untyped in metric %s %s", compliantName, metric,
 				)
 			}
 			n, err = writeOpenMetricsSample(
-				w, name, "", metric, "", 0,
+				w, compliantName, "", metric, "", 0,
 				metric.Untyped.GetValue(), 0, false,
 				nil,
 			)
 		case dto.MetricType_SUMMARY:
 			if metric.Summary == nil {
 				return written, fmt.Errorf(
-					"expected summary in metric %s %s", name, metric,
+					"expected summary in metric %s %s", compliantName, metric,
 				)
 			}
 			for _, q := range metric.Summary.Quantile {
 				n, err = writeOpenMetricsSample(
-					w, name, "", metric,
+					w, compliantName, "", metric,
 					model.QuantileLabel, q.GetQuantile(),
 					q.GetValue(), 0, false,
 					nil,
@@ -210,7 +309,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 				}
 			}
 			n, err = writeOpenMetricsSample(
-				w, name, "_sum", metric, "", 0,
+				w, compliantName, "_sum", metric, "", 0,
 				metric.Summary.GetSampleSum(), 0, false,
 				nil,
 			)
@@ -219,20 +318,24 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 				return
 			}
 			n, err = writeOpenMetricsSample(
-				w, name, "_count", metric, "", 0,
+				w, compliantName, "_count", metric, "", 0,
 				0, metric.Summary.GetSampleCount(), true,
 				nil,
 			)
+			if toOM.withCreatedLines && metric.Summary.CreatedTimestamp != nil {
+				createdTsBytesWritten, err = writeOpenMetricsCreated(w, compliantName, "", metric, "", 0, metric.Summary.GetCreatedTimestamp())
+				n += createdTsBytesWritten
+			}
 		case dto.MetricType_HISTOGRAM:
 			if metric.Histogram == nil {
 				return written, fmt.Errorf(
-					"expected histogram in metric %s %s", name, metric,
+					"expected histogram in metric %s %s", compliantName, metric,
 				)
 			}
 			infSeen := false
 			for _, b := range metric.Histogram.Bucket {
 				n, err = writeOpenMetricsSample(
-					w, name, "_bucket", metric,
+					w, compliantName, "_bucket", metric,
 					model.BucketLabel, b.GetUpperBound(),
 					0, b.GetCumulativeCount(), true,
 					b.Exemplar,
@@ -247,7 +350,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 			}
 			if !infSeen {
 				n, err = writeOpenMetricsSample(
-					w, name, "_bucket", metric,
+					w, compliantName, "_bucket", metric,
 					model.BucketLabel, math.Inf(+1),
 					0, metric.Histogram.GetSampleCount(), true,
 					nil,
@@ -258,7 +361,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 				}
 			}
 			n, err = writeOpenMetricsSample(
-				w, name, "_sum", metric, "", 0,
+				w, compliantName, "_sum", metric, "", 0,
 				metric.Histogram.GetSampleSum(), 0, false,
 				nil,
 			)
@@ -267,13 +370,17 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 				return
 			}
 			n, err = writeOpenMetricsSample(
-				w, name, "_count", metric, "", 0,
+				w, compliantName, "_count", metric, "", 0,
 				0, metric.Histogram.GetSampleCount(), true,
 				nil,
 			)
+			if toOM.withCreatedLines && metric.Histogram.CreatedTimestamp != nil {
+				createdTsBytesWritten, err = writeOpenMetricsCreated(w, compliantName, "", metric, "", 0, metric.Histogram.GetCreatedTimestamp())
+				n += createdTsBytesWritten
+			}
 		default:
 			return written, fmt.Errorf(
-				"unexpected type in metric %s %s", name, metric,
+				"unexpected type in metric %s %s", compliantName, metric,
 			)
 		}
 		written += n
@@ -303,21 +410,9 @@ func writeOpenMetricsSample(
 	floatValue float64, intValue uint64, useIntValue bool,
 	exemplar *dto.Exemplar,
 ) (int, error) {
-	var written int
-	n, err := w.WriteString(name)
-	written += n
-	if err != nil {
-		return written, err
-	}
-	if suffix != "" {
-		n, err = w.WriteString(suffix)
-		written += n
-		if err != nil {
-			return written, err
-		}
-	}
-	n, err = writeOpenMetricsLabelPairs(
-		w, metric.Label, additionalLabelName, additionalLabelValue,
+	written := 0
+	n, err := writeOpenMetricsNameAndLabelPairs(
+		w, name+suffix, metric.Label, additionalLabelName, additionalLabelValue,
 	)
 	written += n
 	if err != nil {
@@ -350,7 +445,7 @@ func writeOpenMetricsSample(
 			return written, err
 		}
 	}
-	if exemplar != nil {
+	if exemplar != nil && len(exemplar.Label) > 0 {
 		n, err = writeExemplar(w, exemplar)
 		written += n
 		if err != nil {
@@ -365,27 +460,58 @@ func writeOpenMetricsSample(
 	return written, nil
 }
 
-// writeOpenMetricsLabelPairs works like writeOpenMetrics but formats the float
-// in OpenMetrics style.
-func writeOpenMetricsLabelPairs(
+// writeOpenMetricsNameAndLabelPairs works like writeOpenMetricsSample but
+// formats the float in OpenMetrics style.
+func writeOpenMetricsNameAndLabelPairs(
 	w enhancedWriter,
+	name string,
 	in []*dto.LabelPair,
 	additionalLabelName string, additionalLabelValue float64,
 ) (int, error) {
-	if len(in) == 0 && additionalLabelName == "" {
-		return 0, nil
-	}
 	var (
-		written   int
-		separator byte = '{'
+		written            int
+		separator          byte = '{'
+		metricInsideBraces      = false
 	)
+
+	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(model.LabelValue(name)) {
+			metricInsideBraces = true
+			err := w.WriteByte(separator)
+			written++
+			if err != nil {
+				return written, err
+			}
+			separator = ','
+		}
+
+		n, err := writeName(w, name)
+		written += n
+		if err != nil {
+			return written, err
+		}
+	}
+
+	if len(in) == 0 && additionalLabelName == "" {
+		if metricInsideBraces {
+			err := w.WriteByte('}')
+			written++
+			if err != nil {
+				return written, err
+			}
+		}
+		return written, nil
+	}
+
 	for _, lp := range in {
 		err := w.WriteByte(separator)
 		written++
 		if err != nil {
 			return written, err
 		}
-		n, err := w.WriteString(lp.GetName())
+		n, err := writeName(w, lp.GetName())
 		written += n
 		if err != nil {
 			return written, err
@@ -442,6 +568,49 @@ func writeOpenMetricsLabelPairs(
 	return written, nil
 }
 
+// writeOpenMetricsCreated writes the created timestamp for a single time series
+// following OpenMetrics text format to w, given the metric name, the metric proto
+// message itself, optionally a suffix to be removed, e.g. '_total' for counters,
+// an additional label name with a float64 value (use empty string as label name if
+// not required) and the timestamp that represents the created timestamp.
+// The function returns the number of bytes written and any error encountered.
+func writeOpenMetricsCreated(w enhancedWriter,
+	name, suffixToTrim string, metric *dto.Metric,
+	additionalLabelName string, additionalLabelValue float64,
+	createdTimestamp *timestamppb.Timestamp,
+) (int, error) {
+	written := 0
+	n, err := writeOpenMetricsNameAndLabelPairs(
+		w, strings.TrimSuffix(name, suffixToTrim)+"_created", metric.Label, additionalLabelName, additionalLabelValue,
+	)
+	written += n
+	if err != nil {
+		return written, err
+	}
+
+	err = w.WriteByte(' ')
+	written++
+	if err != nil {
+		return written, err
+	}
+
+	// TODO(beorn7): Format this directly from components of ts to
+	// avoid overflow/underflow and precision issues of the float
+	// conversion.
+	n, err = writeOpenMetricsFloat(w, float64(createdTimestamp.AsTime().UnixNano())/1e9)
+	written += n
+	if err != nil {
+		return written, err
+	}
+
+	err = w.WriteByte('\n')
+	written++
+	if err != nil {
+		return written, err
+	}
+	return written, nil
+}
+
 // writeExemplar writes the provided exemplar in OpenMetrics format to w. The
 // function returns the number of bytes written and any error encountered.
 func writeExemplar(w enhancedWriter, e *dto.Exemplar) (int, error) {
@@ -451,7 +620,7 @@ func writeExemplar(w enhancedWriter, e *dto.Exemplar) (int, error) {
 	if err != nil {
 		return written, err
 	}
-	n, err = writeOpenMetricsLabelPairs(w, e.Label, "", 0)
+	n, err = writeOpenMetricsNameAndLabelPairs(w, "", e.Label, "", 0)
 	written += n
 	if err != nil {
 		return written, err

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

@@ -62,6 +62,18 @@ var (
 // contains duplicate metrics or invalid metric or label names, the conversion
 // will result in invalid text format output.
 //
+// If metric names conform to the legacy validation pattern, they will be placed
+// outside the brackets in the traditional way, like `foo{}`. If the metric name
+// fails the legacy validation check, it will be placed quoted inside the
+// brackets: `{"foo"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
+// Similar to metric names, if label names conform to the legacy validation
+// pattern, they will be unquoted as normal, like `foo{bar="baz"}`. If the label
+// name fails the legacy validation check, it will be quoted:
+// `foo{"bar"="baz"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
 // This method fulfills the type 'prometheus.encoder'.
 func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err error) {
 	// Fail-fast checks.
@@ -98,7 +110,7 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 		if err != nil {
 			return
 		}
-		n, err = w.WriteString(name)
+		n, err = writeName(w, name)
 		written += n
 		if err != nil {
 			return
@@ -124,7 +136,7 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 	if err != nil {
 		return
 	}
-	n, err = w.WriteString(name)
+	n, err = writeName(w, name)
 	written += n
 	if err != nil {
 		return
@@ -280,21 +292,9 @@ func writeSample(
 	additionalLabelName string, additionalLabelValue float64,
 	value float64,
 ) (int, error) {
-	var written int
-	n, err := w.WriteString(name)
-	written += n
-	if err != nil {
-		return written, err
-	}
-	if suffix != "" {
-		n, err = w.WriteString(suffix)
-		written += n
-		if err != nil {
-			return written, err
-		}
-	}
-	n, err = writeLabelPairs(
-		w, metric.Label, additionalLabelName, additionalLabelValue,
+	written := 0
+	n, err := writeNameAndLabelPairs(
+		w, name+suffix, metric.Label, additionalLabelName, additionalLabelValue,
 	)
 	written += n
 	if err != nil {
@@ -330,32 +330,64 @@ func writeSample(
 	return written, nil
 }
 
-// writeLabelPairs converts a slice of LabelPair proto messages plus the
-// explicitly given additional label pair into text formatted as required by the
-// text format and writes it to 'w'. An empty slice in combination with an empty
-// string 'additionalLabelName' results in nothing being written. Otherwise, the
-// label pairs are written, escaped as required by the text format, and enclosed
-// in '{...}'. The function returns the number of bytes written and any error
-// encountered.
-func writeLabelPairs(
+// writeNameAndLabelPairs converts a slice of LabelPair proto messages plus the
+// explicitly given metric name and additional label pair into text formatted as
+// required by the text format and writes it to 'w'. An empty slice in
+// combination with an empty string 'additionalLabelName' results in nothing
+// being written. Otherwise, the label pairs are written, escaped as required by
+// the text format, and enclosed in '{...}'. The function returns the number of
+// bytes written and any error encountered. If the metric name is not
+// legacy-valid, it will be put inside the brackets as well. Legacy-invalid
+// label names will also be quoted.
+func writeNameAndLabelPairs(
 	w enhancedWriter,
+	name string,
 	in []*dto.LabelPair,
 	additionalLabelName string, additionalLabelValue float64,
 ) (int, error) {
-	if len(in) == 0 && additionalLabelName == "" {
-		return 0, nil
-	}
 	var (
-		written   int
-		separator byte = '{'
+		written            int
+		separator          byte = '{'
+		metricInsideBraces      = false
 	)
+
+	if name != "" {
+		// If the name does not pass the legacy validity check, we must put the
+		// metric name inside the braces.
+		if !model.IsValidLegacyMetricName(model.LabelValue(name)) {
+			metricInsideBraces = true
+			err := w.WriteByte(separator)
+			written++
+			if err != nil {
+				return written, err
+			}
+			separator = ','
+		}
+		n, err := writeName(w, name)
+		written += n
+		if err != nil {
+			return written, err
+		}
+	}
+
+	if len(in) == 0 && additionalLabelName == "" {
+		if metricInsideBraces {
+			err := w.WriteByte('}')
+			written++
+			if err != nil {
+				return written, err
+			}
+		}
+		return written, nil
+	}
+
 	for _, lp := range in {
 		err := w.WriteByte(separator)
 		written++
 		if err != nil {
 			return written, err
 		}
-		n, err := w.WriteString(lp.GetName())
+		n, err := writeName(w, lp.GetName())
 		written += n
 		if err != nil {
 			return written, err
@@ -462,3 +494,27 @@ func writeInt(w enhancedWriter, i int64) (int, error) {
 	numBufPool.Put(bp)
 	return written, err
 }
+
+// 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(model.LabelValue(name)) {
+		return w.WriteString(name)
+	}
+	var written int
+	var err error
+	err = w.WriteByte('"')
+	written++
+	if err != nil {
+		return written, err
+	}
+	var n int
+	n, err = writeEscapedString(w, name, true)
+	written += n
+	if err != nil {
+		return written, err
+	}
+	err = w.WriteByte('"')
+	written++
+	return written, err
+}

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

@@ -16,6 +16,7 @@ package expfmt
 import (
 	"bufio"
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -24,8 +25,9 @@ import (
 
 	dto "github.com/prometheus/client_model/go"
 
-	"github.com/prometheus/common/model"
 	"google.golang.org/protobuf/proto"
+
+	"github.com/prometheus/common/model"
 )
 
 // A stateFn is a function that represents a state in a state machine. By
@@ -112,7 +114,7 @@ func (p *TextParser) TextToMetricFamilies(in io.Reader) (map[string]*dto.MetricF
 	// stream. Turn this error into something nicer and more
 	// meaningful. (io.EOF is often used as a signal for the legitimate end
 	// of an input stream.)
-	if p.err == io.EOF {
+	if p.err != nil && errors.Is(p.err, io.EOF) {
 		p.parseError("unexpected end of input stream")
 	}
 	return p.metricFamiliesByName, p.err
@@ -146,7 +148,7 @@ func (p *TextParser) startOfLine() stateFn {
 		// which is not an error but the signal that we are done.
 		// Any other error that happens to align with the start of
 		// a line is still an error.
-		if p.err == io.EOF {
+		if errors.Is(p.err, io.EOF) {
 			p.err = nil
 		}
 		return nil