Modernize invertergui: MQTT write support, HA integration, UI updates

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

@@ -14,6 +14,7 @@
 package model
 
 import (
+	"errors"
 	"fmt"
 	"time"
 )
@@ -64,7 +65,7 @@ func (a *Alert) Resolved() bool {
 	return a.ResolvedAt(time.Now())
 }
 
-// ResolvedAt returns true off the activity interval ended before
+// ResolvedAt returns true iff the activity interval ended before
 // the given timestamp.
 func (a *Alert) ResolvedAt(ts time.Time) bool {
 	if a.EndsAt.IsZero() {
@@ -75,7 +76,12 @@ func (a *Alert) ResolvedAt(ts time.Time) bool {
 
 // Status returns the status of the alert.
 func (a *Alert) Status() AlertStatus {
-	if a.Resolved() {
+	return a.StatusAt(time.Now())
+}
+
+// StatusAt returns the status of the alert at the given timestamp.
+func (a *Alert) StatusAt(ts time.Time) AlertStatus {
+	if a.ResolvedAt(ts) {
 		return AlertResolved
 	}
 	return AlertFiring
@@ -84,16 +90,16 @@ func (a *Alert) Status() AlertStatus {
 // Validate checks whether the alert data is inconsistent.
 func (a *Alert) Validate() error {
 	if a.StartsAt.IsZero() {
-		return fmt.Errorf("start time missing")
+		return errors.New("start time missing")
 	}
 	if !a.EndsAt.IsZero() && a.EndsAt.Before(a.StartsAt) {
-		return fmt.Errorf("start time must be before end time")
+		return errors.New("start time must be before end time")
 	}
 	if err := a.Labels.Validate(); err != nil {
 		return fmt.Errorf("invalid label set: %w", err)
 	}
 	if len(a.Labels) == 0 {
-		return fmt.Errorf("at least one label pair required")
+		return errors.New("at least one label pair required")
 	}
 	if err := a.Annotations.Validate(); err != nil {
 		return fmt.Errorf("invalid annotations: %w", err)
@@ -127,6 +133,17 @@ func (as Alerts) HasFiring() bool {
 	return false
 }
 
+// HasFiringAt returns true iff one of the alerts is not resolved
+// at the time ts.
+func (as Alerts) HasFiringAt(ts time.Time) bool {
+	for _, a := range as {
+		if !a.ResolvedAt(ts) {
+			return true
+		}
+	}
+	return false
+}
+
 // Status returns StatusFiring iff at least one of the alerts is firing.
 func (as Alerts) Status() AlertStatus {
 	if as.HasFiring() {
@@ -134,3 +151,12 @@ func (as Alerts) Status() AlertStatus {
 	}
 	return AlertResolved
 }
+
+// StatusAt returns StatusFiring iff at least one of the alerts is firing
+// at the time ts.
+func (as Alerts) StatusAt(ts time.Time) AlertStatus {
+	if as.HasFiringAt(ts) {
+		return AlertFiring
+	}
+	return AlertResolved
+}

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

@@ -22,7 +22,7 @@ import (
 )
 
 const (
-	// AlertNameLabel is the name of the label containing the an alert's name.
+	// AlertNameLabel is the name of the label containing the alert's name.
 	AlertNameLabel = "alertname"
 
 	// ExportedLabelPrefix is the prefix to prepend to the label names present in
@@ -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.
@@ -97,27 +103,24 @@ var LabelNameRE = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")
 // therewith.
 type LabelName string
 
-// IsValid returns true iff name matches the pattern of LabelNameRE for legacy
-// names, and iff it's valid UTF-8 if NameValidationScheme is set to
-// UTF8Validation. For the legacy matching, it does not use LabelNameRE for the
-// check but a much faster hardcoded implementation.
+// 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:
-		for i, b := range ln {
-			if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
-				return false
-			}
-		}
-	case UTF8Validation:
-		return utf8.ValidString(string(ln))
-	default:
-		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
-	}
-	return true
+	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 {
+	return LegacyValidation.IsValidLabelName(string(ln))
 }
 
 // UnmarshalYAML implements the yaml.Unmarshaler interface.

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

@@ -14,12 +14,9 @@
 package model
 
 import (
-	"bytes"
 	"encoding/json"
 	"fmt"
-	"slices"
 	"sort"
-	"strconv"
 )
 
 // A LabelSet is a collection of LabelName and LabelValue pairs.  The LabelSet
@@ -117,10 +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
 	}
 
@@ -131,29 +128,6 @@ func (l LabelSet) Merge(other LabelSet) LabelSet {
 	return result
 }
 
-// String will look like `{foo="bar", more="less"}`. Names are sorted alphabetically.
-func (l LabelSet) String() string {
-	var lna [32]LabelName // On stack to avoid memory allocation for sorting names.
-	labelNames := lna[:0]
-	for name := range l {
-		labelNames = append(labelNames, name)
-	}
-	slices.Sort(labelNames)
-	var bytea [1024]byte // On stack to avoid memory allocation while building the output.
-	b := bytes.NewBuffer(bytea[:0])
-	b.WriteByte('{')
-	for i, name := range labelNames {
-		if i > 0 {
-			b.WriteString(", ")
-		}
-		b.WriteString(string(name))
-		b.WriteByte('=')
-		b.Write(strconv.AppendQuote(b.AvailableBuffer(), string(l[name])))
-	}
-	b.WriteByte('}')
-	return b.String()
-}
-
 // Fingerprint returns the LabelSet's fingerprint.
 func (ls LabelSet) Fingerprint() Fingerprint {
 	return labelSetToFingerprint(ls)
@@ -166,7 +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
@@ -179,6 +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

@@ -14,30 +14,49 @@
 package model
 
 import (
+	"encoding/json"
+	"errors"
 	"fmt"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 	"unicode/utf8"
 
 	dto "github.com/prometheus/client_model/go"
+	"go.yaml.in/yaml/v2"
 	"google.golang.org/protobuf/proto"
 )
 
 var (
-	// NameValidationScheme determines the method of name validation to be used by
-	// all calls to IsValidMetricName() and LabelName IsValid(). Setting UTF-8 mode
-	// in isolation from other components that don't support UTF-8 may result in
-	// bugs or other undefined behavior. This value is intended to be set by
-	// UTF-8-aware binaries as part of their startup. To avoid need for locking,
-	// this value should be set once, ideally in an init(), before multiple
-	// goroutines are started.
-	NameValidationScheme = LegacyValidation
+	// NameValidationScheme determines the global default method of the name
+	// validation to be used by all calls to IsValidMetricName() and LabelName
+	// IsValid().
+	//
+	// Deprecated: This variable should not be used and might be removed in the
+	// far future. If you wish to stick to the legacy name validation use
+	// `IsValidLegacyMetricName()` and `LabelName.IsValidLegacy()` methods
+	// instead. This variable is here as an escape hatch for emergency cases,
+	// given the recent change from `LegacyValidation` to `UTF8Validation`, e.g.,
+	// to delay UTF-8 migrations in time or aid in debugging unforeseen results of
+	// the change. In such a case, a temporary assignment to `LegacyValidation`
+	// value in the `init()` function in your main.go or so, could be considered.
+	//
+	// Historically we opted for a global variable for feature gating different
+	// validation schemes in operations that were not otherwise easily adjustable
+	// (e.g. Labels yaml unmarshaling). That could have been a mistake, a separate
+	// Labels structure or package might have been a better choice. Given the
+	// change was made and many upgraded the common already, we live this as-is
+	// with this warning and learning for the future.
+	NameValidationScheme = UTF8Validation
 
-	// NameEscapingScheme defines the default way that names will be
-	// escaped when presented to systems that do not support UTF-8 names. If the
-	// Content-Type "escaping" term is specified, that will override this value.
-	NameEscapingScheme = ValueEncodingEscaping
+	// NameEscapingScheme defines the default way that names will be escaped when
+	// presented to systems that do not support UTF-8 names. If the Content-Type
+	// "escaping" term is specified, that will override this value.
+	// NameEscapingScheme should not be set to the NoEscaping value. That string
+	// is used in content negotiation to indicate that a system supports UTF-8 and
+	// has that feature enabled.
+	NameEscapingScheme = UnderscoreEscaping
 )
 
 // ValidationScheme is a Go enum for determining how metric and label names will
@@ -45,16 +64,151 @@ var (
 type ValidationScheme int
 
 const (
-	// LegacyValidation is a setting that requirets that metric and label names
+	// 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 (
@@ -84,7 +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"
@@ -158,34 +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(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.
-func IsValidLegacyMetricName(n LabelValue) bool {
-	if len(n) == 0 {
-		return false
-	}
-	for i, b := range n {
-		if !isValidLegacyRune(b, i) {
-			return false
-		}
-	}
-	return true
+//
+// Deprecated: This function should not be used and might be removed in the future.
+// Use [LegacyValidation.IsValidMetricName] instead.
+func IsValidLegacyMetricName(n string) bool {
+	return LegacyValidation.IsValidMetricName(n)
 }
 
 // EscapeMetricFamily escapes the given metric names and labels with the given
@@ -208,7 +350,7 @@ func EscapeMetricFamily(v *dto.MetricFamily, scheme EscapingScheme) *dto.MetricF
 	}
 
 	// If the name is nil, copy as-is, don't try to escape.
-	if v.Name == nil || IsValidLegacyMetricName(LabelValue(v.GetName())) {
+	if v.Name == nil || IsValidLegacyMetricName(v.GetName()) {
 		out.Name = v.Name
 	} else {
 		out.Name = proto.String(EscapeName(v.GetName(), scheme))
@@ -230,7 +372,7 @@ func EscapeMetricFamily(v *dto.MetricFamily, scheme EscapingScheme) *dto.MetricF
 
 		for _, l := range m.Label {
 			if l.GetName() == MetricNameLabel {
-				if l.Value == nil || IsValidLegacyMetricName(LabelValue(l.GetValue())) {
+				if l.Value == nil || IsValidLegacyMetricName(l.GetValue()) {
 					escaped.Label = append(escaped.Label, l)
 					continue
 				}
@@ -240,7 +382,7 @@ func EscapeMetricFamily(v *dto.MetricFamily, scheme EscapingScheme) *dto.MetricF
 				})
 				continue
 			}
-			if l.Name == nil || IsValidLegacyMetricName(LabelValue(l.GetName())) {
+			if l.Name == nil || IsValidLegacyMetricName(l.GetName()) {
 				escaped.Label = append(escaped.Label, l)
 				continue
 			}
@@ -256,20 +398,16 @@ func EscapeMetricFamily(v *dto.MetricFamily, scheme EscapingScheme) *dto.MetricF
 
 func metricNeedsEscaping(m *dto.Metric) bool {
 	for _, l := range m.Label {
-		if l.GetName() == MetricNameLabel && !IsValidLegacyMetricName(LabelValue(l.GetValue())) {
+		if l.GetName() == MetricNameLabel && !IsValidLegacyMetricName(l.GetValue()) {
 			return true
 		}
-		if !IsValidLegacyMetricName(LabelValue(l.GetName())) {
+		if !IsValidLegacyMetricName(l.GetName()) {
 			return true
 		}
 	}
 	return false
 }
 
-const (
-	lowerhex = "0123456789abcdef"
-)
-
 // EscapeName escapes the incoming name according to the provided escaping
 // scheme. Depending on the rules of escaping, this may cause no change in the
 // string that is returned. (Especially NoEscaping, which by definition is a
@@ -283,7 +421,7 @@ func EscapeName(name string, scheme EscapingScheme) string {
 	case NoEscaping:
 		return name
 	case UnderscoreEscaping:
-		if IsValidLegacyMetricName(LabelValue(name)) {
+		if IsValidLegacyMetricName(name) {
 			return name
 		}
 		for i, b := range name {
@@ -297,38 +435,34 @@ 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 {
-				escaped.WriteRune('_')
+			default:
+				escaped.WriteString("__")
 			}
 		}
 		return escaped.String()
 	case ValueEncodingEscaping:
-		if IsValidLegacyMetricName(LabelValue(name)) {
+		if IsValidLegacyMetricName(name) {
 			return name
 		}
 		escaped.WriteString("U__")
 		for i, b := range name {
-			if isValidLegacyRune(b, i) {
+			switch {
+			case b == '_':
+				escaped.WriteString("__")
+			case isValidLegacyRune(b, i):
 				escaped.WriteRune(b)
-			} else if !utf8.ValidRune(b) {
+			case !utf8.ValidRune(b):
 				escaped.WriteString("_FFFD_")
-			} else if b < 0x100 {
+			default:
 				escaped.WriteRune('_')
-				for s := 4; s >= 0; s -= 4 {
-					escaped.WriteByte(lowerhex[b>>uint(s)&0xF])
-				}
-				escaped.WriteRune('_')
-			} else if b < 0x10000 {
-				escaped.WriteRune('_')
-				for s := 12; s >= 0; s -= 4 {
-					escaped.WriteByte(lowerhex[b>>uint(s)&0xF])
-				}
+				escaped.WriteString(strconv.FormatInt(int64(b), 16))
 				escaped.WriteRune('_')
 			}
 		}
@@ -338,7 +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')
 }
@@ -386,8 +520,9 @@ func UnescapeName(name string, scheme EscapingScheme) string {
 			// We think we are in a UTF-8 code, process it.
 			var utf8Val uint
 			for j := 0; i < len(escapedName); j++ {
-				// This is too many characters for a utf8 value.
-				if j > 4 {
+				// This is too many characters for a utf8 value based on the MaxRune
+				// value of '\U0010FFFF'.
+				if j >= 6 {
 					return name
 				}
 				// Found a closing underscore, convert to a rune, check validity, and append.
@@ -401,11 +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++
@@ -440,7 +576,7 @@ func (e EscapingScheme) String() string {
 
 func ToEscapingScheme(s string) (EscapingScheme, error) {
 	if s == "" {
-		return NoEscaping, fmt.Errorf("got empty string instead of escaping scheme")
+		return NoEscaping, errors.New("got empty string instead of escaping scheme")
 	}
 	switch s {
 	case AllowUTF8:
@@ -452,6 +588,6 @@ func ToEscapingScheme(s string) (EscapingScheme, error) {
 	case EscapeValues:
 		return ValueEncodingEscaping, nil
 	default:
-		return NoEscaping, fmt.Errorf("unknown format scheme " + s)
+		return NoEscaping, fmt.Errorf("unknown format scheme %s", s)
 	}
 }

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

@@ -15,6 +15,7 @@ package model
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"regexp"
 	"time"
@@ -34,7 +35,7 @@ func (m *Matcher) UnmarshalJSON(b []byte) error {
 	}
 
 	if len(m.Name) == 0 {
-		return fmt.Errorf("label name in matcher must not be empty")
+		return errors.New("label name in matcher must not be empty")
 	}
 	if m.IsRegex {
 		if _, err := regexp.Compile(m.Value); err != nil {
@@ -77,7 +78,7 @@ type Silence struct {
 // Validate returns true iff all fields of the silence have valid values.
 func (s *Silence) Validate() error {
 	if len(s.Matchers) == 0 {
-		return fmt.Errorf("at least one matcher required")
+		return errors.New("at least one matcher required")
 	}
 	for _, m := range s.Matchers {
 		if err := m.Validate(); err != nil {
@@ -85,22 +86,22 @@ func (s *Silence) Validate() error {
 		}
 	}
 	if s.StartsAt.IsZero() {
-		return fmt.Errorf("start time missing")
+		return errors.New("start time missing")
 	}
 	if s.EndsAt.IsZero() {
-		return fmt.Errorf("end time missing")
+		return errors.New("end time missing")
 	}
 	if s.EndsAt.Before(s.StartsAt) {
-		return fmt.Errorf("start time must be before end time")
+		return errors.New("start time must be before end time")
 	}
 	if s.CreatedBy == "" {
-		return fmt.Errorf("creator information missing")
+		return errors.New("creator information missing")
 	}
 	if s.Comment == "" {
-		return fmt.Errorf("comment missing")
+		return errors.New("comment missing")
 	}
 	if s.CreatedAt.IsZero() {
-		return fmt.Errorf("creation timestamp missing")
+		return errors.New("creation timestamp missing")
 	}
 	return nil
 }

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"
 }
 
@@ -201,6 +201,7 @@ var unitMap = map[string]struct {
 
 // ParseDuration parses a string into a time.Duration, assuming that a year
 // always has 365d, a week always has 7d, and a day always has 24h.
+// Negative durations are not supported.
 func ParseDuration(s string) (Duration, error) {
 	switch s {
 	case "0":
@@ -253,18 +254,36 @@ func ParseDuration(s string) (Duration, error) {
 			return 0, errors.New("duration out of range")
 		}
 	}
+
 	return Duration(dur), nil
 }
 
+// ParseDurationAllowNegative is like ParseDuration but also accepts negative durations.
+func ParseDurationAllowNegative(s string) (Duration, error) {
+	if s == "" || s[0] != '-' {
+		return ParseDuration(s)
+	}
+
+	d, err := ParseDuration(s[1:])
+
+	return -d, err
+}
+
 func (d Duration) String() string {
 	var (
-		ms = int64(time.Duration(d) / time.Millisecond)
-		r  = ""
+		ms   = int64(time.Duration(d) / time.Millisecond)
+		r    = ""
+		sign = ""
 	)
+
 	if ms == 0 {
 		return "0s"
 	}
 
+	if ms < 0 {
+		sign, ms = "-", -ms
+	}
+
 	f := func(unit string, mult int64, exact bool) {
 		if exact && ms%mult != 0 {
 			return
@@ -286,7 +305,7 @@ func (d Duration) String() string {
 	f("s", 1000, false)
 	f("ms", 1, false)
 
-	return r
+	return sign + r
 }
 
 // MarshalJSON implements the json.Marshaler interface.

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_float.go

@@ -15,6 +15,7 @@ package model
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"math"
 	"strconv"
@@ -39,7 +40,7 @@ func (v SampleValue) MarshalJSON() ([]byte, error) {
 // UnmarshalJSON implements json.Unmarshaler.
 func (v *SampleValue) UnmarshalJSON(b []byte) error {
 	if len(b) < 2 || b[0] != '"' || b[len(b)-1] != '"' {
-		return fmt.Errorf("sample value must be a quoted string")
+		return errors.New("sample value must be a quoted string")
 	}
 	f, err := strconv.ParseFloat(string(b[1:len(b)-1]), 64)
 	if err != nil {

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

@@ -15,6 +15,7 @@ package model
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -32,7 +33,7 @@ func (v FloatString) MarshalJSON() ([]byte, error) {
 
 func (v *FloatString) UnmarshalJSON(b []byte) error {
 	if len(b) < 2 || b[0] != '"' || b[len(b)-1] != '"' {
-		return fmt.Errorf("float value must be a quoted string")
+		return errors.New("float value must be a quoted string")
 	}
 	f, err := strconv.ParseFloat(string(b[1:len(b)-1]), 64)
 	if err != nil {
@@ -85,22 +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()
 }
 
@@ -141,7 +142,7 @@ type SampleHistogramPair struct {
 
 func (s SampleHistogramPair) MarshalJSON() ([]byte, error) {
 	if s.Histogram == nil {
-		return nil, fmt.Errorf("histogram is nil")
+		return nil, errors.New("histogram is nil")
 	}
 	t, err := json.Marshal(s.Timestamp)
 	if err != nil {
@@ -164,7 +165,7 @@ func (s *SampleHistogramPair) UnmarshalJSON(buf []byte) error {
 		return fmt.Errorf("wrong number of fields: %d != %d", gotLen, wantLen)
 	}
 	if s.Histogram == nil {
-		return fmt.Errorf("histogram is null")
+		return errors.New("histogram is null")
 	}
 	return nil
 }

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: