Make metric/label name validation scheme explicit (#16928)

* Parameterize metric/label name validation scheme

Parameterized metric/label name validation scheme

---------

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
Co-authored-by: Julius Hinze <julius.hinze@grafana.com>

cmd/prometheus/main.go

@@ -651,7 +651,7 @@ func main() {
 	}
 
 	// Parse rule files to verify they exist and contain valid rules.
-	if err := rules.ParseFiles(cfgFile.RuleFiles); err != nil {
+	if err := rules.ParseFiles(cfgFile.RuleFiles, cfgFile.GlobalConfig.MetricNameValidationScheme); err != nil {
 		absPath, pathErr := filepath.Abs(cfg.configFile)
 		if pathErr != nil {
 			absPath = cfg.configFile
@@ -790,7 +790,7 @@ func main() {
 		ctxWeb, cancelWeb = context.WithCancel(context.Background())
 		ctxRule           = context.Background()
 
-		notifierManager = notifier.NewManager(&cfg.notifier, logger.With("component", "notifier"))
+		notifierManager = notifier.NewManager(&cfg.notifier, cfgFile.GlobalConfig.MetricNameValidationScheme, logger.With("component", "notifier"))
 
 		ctxScrape, cancelScrape = context.WithCancel(context.Background())
 		ctxNotify, cancelNotify = context.WithCancel(context.Background())
@@ -867,6 +867,7 @@ func main() {
 		queryEngine = promql.NewEngine(opts)
 
 		ruleManager = rules.NewManager(&rules.ManagerOptions{
+			NameValidationScheme:   cfgFile.GlobalConfig.MetricNameValidationScheme,
 			Appendable:             fanoutStorage,
 			Queryable:              localStorage,
 			QueryFunc:              rules.EngineQueryFunc(queryEngine, fanoutStorage),

cmd/promtool/main.go

@@ -359,7 +359,7 @@ func main() {
 		os.Exit(CheckSD(*sdConfigFile, *sdJobName, *sdTimeout, prometheus.DefaultRegisterer))
 
 	case checkConfigCmd.FullCommand():
-		os.Exit(CheckConfig(*agentMode, *checkConfigSyntaxOnly, newConfigLintConfig(*checkConfigLint, *checkConfigLintFatal, *checkConfigIgnoreUnknownFields, model.Duration(*checkLookbackDelta)), *configFiles...))
+		os.Exit(CheckConfig(*agentMode, *checkConfigSyntaxOnly, newConfigLintConfig(*checkConfigLint, *checkConfigLintFatal, *checkConfigIgnoreUnknownFields, model.UTF8Validation, model.Duration(*checkLookbackDelta)), *configFiles...))
 
 	case checkServerHealthCmd.FullCommand():
 		os.Exit(checkErr(CheckServerStatus(serverURL, checkHealth, httpRoundTripper)))
@@ -371,7 +371,7 @@ func main() {
 		os.Exit(CheckWebConfig(*webConfigFiles...))
 
 	case checkRulesCmd.FullCommand():
-		os.Exit(CheckRules(newRulesLintConfig(*checkRulesLint, *checkRulesLintFatal, *checkRulesIgnoreUnknownFields), *ruleFiles...))
+		os.Exit(CheckRules(newRulesLintConfig(*checkRulesLint, *checkRulesLintFatal, *checkRulesIgnoreUnknownFields, model.UTF8Validation), *ruleFiles...))
 
 	case checkMetricsCmd.FullCommand():
 		os.Exit(CheckMetrics(*checkMetricsExtended))
@@ -436,7 +436,7 @@ func main() {
 		os.Exit(backfillOpenMetrics(*importFilePath, *importDBPath, *importHumanReadable, *importQuiet, *maxBlockDuration, *openMetricsLabels))
 
 	case importRulesCmd.FullCommand():
-		os.Exit(checkErr(importRules(serverURL, httpRoundTripper, *importRulesStart, *importRulesEnd, *importRulesOutputDir, *importRulesEvalInterval, *maxBlockDuration, *importRulesFiles...)))
+		os.Exit(checkErr(importRules(serverURL, httpRoundTripper, *importRulesStart, *importRulesEnd, *importRulesOutputDir, *importRulesEvalInterval, *maxBlockDuration, model.UTF8Validation, *importRulesFiles...)))
 
 	case queryAnalyzeCmd.FullCommand():
 		os.Exit(checkErr(queryAnalyzeCfg.run(serverURL, httpRoundTripper)))
@@ -468,17 +468,19 @@ func checkExperimental(f bool) {
 var errLint = errors.New("lint error")
 
 type rulesLintConfig struct {
-	all                 bool
-	duplicateRules      bool
-	fatal               bool
-	ignoreUnknownFields bool
+	all                  bool
+	duplicateRules       bool
+	fatal                bool
+	ignoreUnknownFields  bool
+	nameValidationScheme model.ValidationScheme
 }
 
-func newRulesLintConfig(stringVal string, fatal, ignoreUnknownFields bool) rulesLintConfig {
+func newRulesLintConfig(stringVal string, fatal, ignoreUnknownFields bool, nameValidationScheme model.ValidationScheme) rulesLintConfig {
 	items := strings.Split(stringVal, ",")
 	ls := rulesLintConfig{
-		fatal:               fatal,
-		ignoreUnknownFields: ignoreUnknownFields,
+		fatal:                fatal,
+		ignoreUnknownFields:  ignoreUnknownFields,
+		nameValidationScheme: nameValidationScheme,
 	}
 	for _, setting := range items {
 		switch setting {
@@ -504,7 +506,7 @@ type configLintConfig struct {
 	lookbackDelta model.Duration
 }
 
-func newConfigLintConfig(optionsStr string, fatal, ignoreUnknownFields bool, lookbackDelta model.Duration) configLintConfig {
+func newConfigLintConfig(optionsStr string, fatal, ignoreUnknownFields bool, nameValidationScheme model.ValidationScheme, lookbackDelta model.Duration) configLintConfig {
 	c := configLintConfig{
 		rulesLintConfig: rulesLintConfig{
 			fatal: fatal,
@@ -533,7 +535,7 @@ func newConfigLintConfig(optionsStr string, fatal, ignoreUnknownFields bool, loo
 	}
 
 	if len(rulesOptions) > 0 {
-		c.rulesLintConfig = newRulesLintConfig(strings.Join(rulesOptions, ","), fatal, ignoreUnknownFields)
+		c.rulesLintConfig = newRulesLintConfig(strings.Join(rulesOptions, ","), fatal, ignoreUnknownFields, nameValidationScheme)
 	}
 
 	return c
@@ -854,7 +856,7 @@ func checkRulesFromStdin(ls rulesLintConfig) (bool, bool) {
 		fmt.Fprintln(os.Stderr, "  FAILED:", err)
 		return true, true
 	}
-	rgs, errs := rulefmt.Parse(data, ls.ignoreUnknownFields)
+	rgs, errs := rulefmt.Parse(data, ls.ignoreUnknownFields, ls.nameValidationScheme)
 	if errs != nil {
 		failed = true
 		fmt.Fprintln(os.Stderr, "  FAILED:")
@@ -888,7 +890,7 @@ func checkRules(files []string, ls rulesLintConfig) (bool, bool) {
 	hasErrors := false
 	for _, f := range files {
 		fmt.Println("Checking", f)
-		rgs, errs := rulefmt.ParseFile(f, ls.ignoreUnknownFields)
+		rgs, errs := rulefmt.ParseFile(f, ls.ignoreUnknownFields, ls.nameValidationScheme)
 		if errs != nil {
 			failed = true
 			fmt.Fprintln(os.Stderr, "  FAILED:")
@@ -1225,7 +1227,7 @@ func (*jsonPrinter) printLabelValues(v model.LabelValues) {
 
 // importRules backfills recording rules from the files provided. The output are blocks of data
 // at the outputDir location.
-func importRules(url *url.URL, roundTripper http.RoundTripper, start, end, outputDir string, evalInterval, maxBlockDuration time.Duration, files ...string) error {
+func importRules(url *url.URL, roundTripper http.RoundTripper, start, end, outputDir string, evalInterval, maxBlockDuration time.Duration, nameValidationScheme model.ValidationScheme, files ...string) error {
 	ctx := context.Background()
 	var stime, etime time.Time
 	var err error
@@ -1248,11 +1250,12 @@ func importRules(url *url.URL, roundTripper http.RoundTripper, start, end, outpu
 	}
 
 	cfg := ruleImporterConfig{
-		outputDir:        outputDir,
-		start:            stime,
-		end:              etime,
-		evalInterval:     evalInterval,
-		maxBlockDuration: maxBlockDuration,
+		outputDir:            outputDir,
+		start:                stime,
+		end:                  etime,
+		evalInterval:         evalInterval,
+		maxBlockDuration:     maxBlockDuration,
+		nameValidationScheme: nameValidationScheme,
 	}
 	api, err := newAPI(url, roundTripper, nil)
 	if err != nil {

cmd/promtool/main_test.go

@@ -186,7 +186,7 @@ func TestCheckDuplicates(t *testing.T) {
 		c := test
 		t.Run(c.name, func(t *testing.T) {
 			t.Parallel()
-			rgs, err := rulefmt.ParseFile(c.ruleFile, false)
+			rgs, err := rulefmt.ParseFile(c.ruleFile, false, model.UTF8Validation)
 			require.Empty(t, err)
 			dups := checkDuplicates(rgs.Groups)
 			require.Equal(t, c.expectedDups, dups)
@@ -195,7 +195,7 @@ func TestCheckDuplicates(t *testing.T) {
 }
 
 func BenchmarkCheckDuplicates(b *testing.B) {
-	rgs, err := rulefmt.ParseFile("./testdata/rules_large.yml", false)
+	rgs, err := rulefmt.ParseFile("./testdata/rules_large.yml", false, model.UTF8Validation)
 	require.Empty(b, err)
 	b.ResetTimer()
 
@@ -509,7 +509,7 @@ func TestCheckRules(t *testing.T) {
 		defer func(v *os.File) { os.Stdin = v }(os.Stdin)
 		os.Stdin = r
 
-		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false))
+		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false, model.UTF8Validation))
 		require.Equal(t, successExitCode, exitCode)
 	})
 
@@ -531,7 +531,7 @@ func TestCheckRules(t *testing.T) {
 		defer func(v *os.File) { os.Stdin = v }(os.Stdin)
 		os.Stdin = r
 
-		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false))
+		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false, model.UTF8Validation))
 		require.Equal(t, failureExitCode, exitCode)
 	})
 
@@ -553,7 +553,7 @@ func TestCheckRules(t *testing.T) {
 		defer func(v *os.File) { os.Stdin = v }(os.Stdin)
 		os.Stdin = r
 
-		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, true, false))
+		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, true, false, model.UTF8Validation))
 		require.Equal(t, lintErrExitCode, exitCode)
 	})
 }
@@ -571,19 +571,19 @@ func TestCheckRulesWithFeatureFlag(t *testing.T) {
 func TestCheckRulesWithRuleFiles(t *testing.T) {
 	t.Run("rules-good", func(t *testing.T) {
 		t.Parallel()
-		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false), "./testdata/rules.yml")
+		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false, model.UTF8Validation), "./testdata/rules.yml")
 		require.Equal(t, successExitCode, exitCode)
 	})
 
 	t.Run("rules-bad", func(t *testing.T) {
 		t.Parallel()
-		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false), "./testdata/rules-bad.yml")
+		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, false, false, model.UTF8Validation), "./testdata/rules-bad.yml")
 		require.Equal(t, failureExitCode, exitCode)
 	})
 
 	t.Run("rules-lint-fatal", func(t *testing.T) {
 		t.Parallel()
-		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, true, false), "./testdata/prometheus-rules.lint.yml")
+		exitCode := CheckRules(newRulesLintConfig(lintOptionDuplicateRules, true, false, model.UTF8Validation), "./testdata/prometheus-rules.lint.yml")
 		require.Equal(t, lintErrExitCode, exitCode)
 	})
 }
@@ -612,20 +612,20 @@ func TestCheckScrapeConfigs(t *testing.T) {
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			// Non-fatal linting.
-			code := CheckConfig(false, false, newConfigLintConfig(lintOptionTooLongScrapeInterval, false, false, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
+			code := CheckConfig(false, false, newConfigLintConfig(lintOptionTooLongScrapeInterval, false, false, model.UTF8Validation, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
 			require.Equal(t, successExitCode, code, "Non-fatal linting should return success")
 			// Fatal linting.
-			code = CheckConfig(false, false, newConfigLintConfig(lintOptionTooLongScrapeInterval, true, false, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
+			code = CheckConfig(false, false, newConfigLintConfig(lintOptionTooLongScrapeInterval, true, false, model.UTF8Validation, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
 			if tc.expectError {
 				require.Equal(t, lintErrExitCode, code, "Fatal linting should return error")
 			} else {
 				require.Equal(t, successExitCode, code, "Fatal linting should return success when there are no problems")
 			}
 			// Check syntax only, no linting.
-			code = CheckConfig(false, true, newConfigLintConfig(lintOptionTooLongScrapeInterval, true, false, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
+			code = CheckConfig(false, true, newConfigLintConfig(lintOptionTooLongScrapeInterval, true, false, model.UTF8Validation, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
 			require.Equal(t, successExitCode, code, "Fatal linting should return success when checking syntax only")
 			// Lint option "none" should disable linting.
-			code = CheckConfig(false, false, newConfigLintConfig(lintOptionNone+","+lintOptionTooLongScrapeInterval, true, false, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
+			code = CheckConfig(false, false, newConfigLintConfig(lintOptionNone+","+lintOptionTooLongScrapeInterval, true, false, model.UTF8Validation, tc.lookbackDelta), "./testdata/prometheus-config.lint.too_long_scrape_interval.yml")
 			require.Equal(t, successExitCode, code, `Fatal linting should return success when lint option "none" is specified`)
 		})
 	}

cmd/promtool/rules.go

@@ -48,11 +48,12 @@ type ruleImporter struct {
 }
 
 type ruleImporterConfig struct {
-	outputDir        string
-	start            time.Time
-	end              time.Time
-	evalInterval     time.Duration
-	maxBlockDuration time.Duration
+	outputDir            string
+	start                time.Time
+	end                  time.Time
+	evalInterval         time.Duration
+	maxBlockDuration     time.Duration
+	nameValidationScheme model.ValidationScheme
 }
 
 // newRuleImporter creates a new rule importer that can be used to parse and evaluate recording rule files and create new series
@@ -60,10 +61,12 @@ type ruleImporterConfig struct {
 func newRuleImporter(logger *slog.Logger, config ruleImporterConfig, apiClient queryRangeAPI) *ruleImporter {
 	logger.Info("new rule importer", "component", "backfiller", "start", config.start.Format(time.RFC822), "end", config.end.Format(time.RFC822))
 	return &ruleImporter{
-		logger:      logger,
-		config:      config,
-		apiClient:   apiClient,
-		ruleManager: rules.NewManager(&rules.ManagerOptions{}),
+		logger:    logger,
+		config:    config,
+		apiClient: apiClient,
+		ruleManager: rules.NewManager(&rules.ManagerOptions{
+			NameValidationScheme: config.nameValidationScheme,
+		}),
 	}
 }
 

cmd/promtool/rules_test.go

@@ -165,11 +165,12 @@ func TestBackfillRuleIntegration(t *testing.T) {
 func newTestRuleImporter(_ context.Context, start time.Time, tmpDir string, testSamples model.Matrix, maxBlockDuration time.Duration) (*ruleImporter, error) {
 	logger := promslog.NewNopLogger()
 	cfg := ruleImporterConfig{
-		outputDir:        tmpDir,
-		start:            start.Add(-10 * time.Hour),
-		end:              start.Add(-7 * time.Hour),
-		evalInterval:     60 * time.Second,
-		maxBlockDuration: maxBlockDuration,
+		outputDir:            tmpDir,
+		start:                start.Add(-10 * time.Hour),
+		end:                  start.Add(-7 * time.Hour),
+		evalInterval:         60 * time.Second,
+		maxBlockDuration:     maxBlockDuration,
+		nameValidationScheme: model.UTF8Validation,
 	}
 
 	return newRuleImporter(logger, cfg, mockQueryRangeAPI{

cmd/promtool/sd_test.go

@@ -42,11 +42,12 @@ func TestSDCheckResult(t *testing.T) {
 		ScrapeInterval: model.Duration(1 * time.Minute),
 		ScrapeTimeout:  model.Duration(10 * time.Second),
 		RelabelConfigs: []*relabel.Config{{
-			SourceLabels: model.LabelNames{"foo"},
-			Action:       relabel.Replace,
-			TargetLabel:  "newfoo",
-			Regex:        reg,
-			Replacement:  "$1",
+			SourceLabels:         model.LabelNames{"foo"},
+			Action:               relabel.Replace,
+			TargetLabel:          "newfoo",
+			Regex:                reg,
+			Replacement:          "$1",
+			NameValidationScheme: model.UTF8Validation,
 		}},
 	}
 

config/config.go

@@ -413,6 +413,10 @@ func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		jobNames[scfg.JobName] = struct{}{}
 	}
 
+	if err := c.AlertingConfig.Validate(c.GlobalConfig.MetricNameValidationScheme); err != nil {
+		return err
+	}
+
 	rwNames := map[string]struct{}{}
 	for _, rwcfg := range c.RemoteWriteConfigs {
 		if rwcfg == nil {
@@ -422,6 +426,9 @@ func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		if _, ok := rwNames[rwcfg.Name]; ok && rwcfg.Name != "" {
 			return fmt.Errorf("found multiple remote write configs with job name %q", rwcfg.Name)
 		}
+		if err := rwcfg.Validate(c.GlobalConfig.MetricNameValidationScheme); err != nil {
+			return err
+		}
 		rwNames[rwcfg.Name] = struct{}{}
 	}
 	rrNames := map[string]struct{}{}
@@ -596,8 +603,14 @@ func (c *GlobalConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		return err
 	}
 
+	switch gc.MetricNameValidationScheme {
+	case model.UTF8Validation, model.LegacyValidation:
+	default:
+		gc.MetricNameValidationScheme = DefaultGlobalConfig.MetricNameValidationScheme
+	}
+
 	if err := gc.ExternalLabels.Validate(func(l labels.Label) error {
-		if !model.LabelName(l.Name).IsValid() {
+		if !gc.MetricNameValidationScheme.IsValidLabelName(l.Name) {
 			return fmt.Errorf("%q is not a valid label name", l.Name)
 		}
 		if !model.LabelValue(l.Value).IsValid() {
@@ -878,11 +891,9 @@ func (c *ScrapeConfig) Validate(globalConfig GlobalConfig) error {
 	}
 
 	switch globalConfig.MetricNameValidationScheme {
-	case model.UnsetValidation:
-		globalConfig.MetricNameValidationScheme = model.UTF8Validation
 	case model.LegacyValidation, model.UTF8Validation:
 	default:
-		return fmt.Errorf("unknown global name validation method specified, must be either '', 'legacy' or 'utf8', got %s", globalConfig.MetricNameValidationScheme)
+		return errors.New("global name validation method must be set")
 	}
 	// Scrapeconfig validation scheme matches global if left blank.
 	localValidationUnset := false
@@ -944,6 +955,17 @@ func (c *ScrapeConfig) Validate(globalConfig GlobalConfig) error {
 		c.AlwaysScrapeClassicHistograms = &global
 	}
 
+	for _, rc := range c.RelabelConfigs {
+		if err := rc.Validate(c.MetricNameValidationScheme); err != nil {
+			return err
+		}
+	}
+	for _, rc := range c.MetricRelabelConfigs {
+		if err := rc.Validate(c.MetricNameValidationScheme); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
 
@@ -1096,6 +1118,20 @@ type AlertingConfig struct {
 	AlertmanagerConfigs AlertmanagerConfigs `yaml:"alertmanagers,omitempty"`
 }
 
+func (c *AlertingConfig) Validate(nameValidationScheme model.ValidationScheme) error {
+	for _, rc := range c.AlertRelabelConfigs {
+		if err := rc.Validate(nameValidationScheme); err != nil {
+			return err
+		}
+	}
+	for _, rc := range c.AlertmanagerConfigs {
+		if err := rc.Validate(nameValidationScheme); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // SetDirectory joins any relative file paths with dir.
 func (c *AlertingConfig) SetDirectory(dir string) {
 	for _, c := range c.AlertmanagerConfigs {
@@ -1240,6 +1276,20 @@ func (c *AlertmanagerConfig) UnmarshalYAML(unmarshal func(interface{}) error) er
 	return nil
 }
 
+func (c *AlertmanagerConfig) Validate(nameValidationScheme model.ValidationScheme) error {
+	for _, rc := range c.AlertRelabelConfigs {
+		if err := rc.Validate(nameValidationScheme); err != nil {
+			return err
+		}
+	}
+	for _, rc := range c.RelabelConfigs {
+		if err := rc.Validate(nameValidationScheme); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // MarshalYAML implements the yaml.Marshaler interface.
 func (c *AlertmanagerConfig) MarshalYAML() (interface{}, error) {
 	return discovery.MarshalYAMLWithInlineConfigs(c)
@@ -1377,6 +1427,16 @@ func (c *RemoteWriteConfig) UnmarshalYAML(unmarshal func(interface{}) error) err
 	return validateAuthConfigs(c)
 }
 
+func (c *RemoteWriteConfig) Validate(nameValidationScheme model.ValidationScheme) error {
+	for _, rc := range c.WriteRelabelConfigs {
+		if err := rc.Validate(nameValidationScheme); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // validateAuthConfigs validates that at most one of basic_auth, authorization, oauth2, sigv4, azuread or google_iam must be configured.
 func validateAuthConfigs(c *RemoteWriteConfig) error {
 	var authConfigured []string

config/config_test.go

@@ -23,6 +23,8 @@ import (
 	"time"
 
 	"github.com/alecthomas/units"
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/grafana/regexp"
 	"github.com/prometheus/common/config"
 	"github.com/prometheus/common/model"
@@ -106,6 +108,7 @@ var expectedConf = &Config{
 		ScrapeProtocols:                DefaultGlobalConfig.ScrapeProtocols,
 		AlwaysScrapeClassicHistograms:  false,
 		ConvertClassicHistogramsToNHCB: false,
+		MetricNameValidationScheme:     model.UTF8Validation,
 	},
 
 	Runtime: RuntimeConfig{
@@ -125,11 +128,12 @@ var expectedConf = &Config{
 			Name:            "drop_expensive",
 			WriteRelabelConfigs: []*relabel.Config{
 				{
-					SourceLabels: model.LabelNames{"__name__"},
-					Separator:    ";",
-					Regex:        relabel.MustNewRegexp("expensive.*"),
-					Replacement:  "$1",
-					Action:       relabel.Drop,
+					SourceLabels:         model.LabelNames{"__name__"},
+					Separator:            ";",
+					Regex:                relabel.MustNewRegexp("expensive.*"),
+					Replacement:          "$1",
+					Action:               relabel.Drop,
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 			QueueConfig:    DefaultQueueConfig,
@@ -279,50 +283,56 @@ var expectedConf = &Config{
 
 			RelabelConfigs: []*relabel.Config{
 				{
-					SourceLabels: model.LabelNames{"job", "__meta_dns_name"},
-					TargetLabel:  "job",
-					Separator:    ";",
-					Regex:        relabel.MustNewRegexp("(.*)some-[regex]"),
-					Replacement:  "foo-${1}",
-					Action:       relabel.Replace,
+					SourceLabels:         model.LabelNames{"job", "__meta_dns_name"},
+					TargetLabel:          "job",
+					Separator:            ";",
+					Regex:                relabel.MustNewRegexp("(.*)some-[regex]"),
+					Replacement:          "foo-${1}",
+					Action:               relabel.Replace,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					SourceLabels: model.LabelNames{"abc"},
-					TargetLabel:  "cde",
-					Separator:    ";",
-					Regex:        relabel.DefaultRelabelConfig.Regex,
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Action:       relabel.Replace,
+					SourceLabels:         model.LabelNames{"abc"},
+					TargetLabel:          "cde",
+					Separator:            ";",
+					Regex:                relabel.DefaultRelabelConfig.Regex,
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.Replace,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					TargetLabel: "abc",
-					Separator:   ";",
-					Regex:       relabel.DefaultRelabelConfig.Regex,
-					Replacement: "static",
-					Action:      relabel.Replace,
+					TargetLabel:          "abc",
+					Separator:            ";",
+					Regex:                relabel.DefaultRelabelConfig.Regex,
+					Replacement:          "static",
+					Action:               relabel.Replace,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					TargetLabel: "abc",
-					Separator:   ";",
-					Regex:       relabel.MustNewRegexp(""),
-					Replacement: "static",
-					Action:      relabel.Replace,
+					TargetLabel:          "abc",
+					Separator:            ";",
+					Regex:                relabel.MustNewRegexp(""),
+					Replacement:          "static",
+					Action:               relabel.Replace,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					SourceLabels: model.LabelNames{"foo"},
-					TargetLabel:  "abc",
-					Action:       relabel.KeepEqual,
-					Regex:        relabel.DefaultRelabelConfig.Regex,
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Separator:    relabel.DefaultRelabelConfig.Separator,
+					SourceLabels:         model.LabelNames{"foo"},
+					TargetLabel:          "abc",
+					Action:               relabel.KeepEqual,
+					Regex:                relabel.DefaultRelabelConfig.Regex,
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Separator:            relabel.DefaultRelabelConfig.Separator,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					SourceLabels: model.LabelNames{"foo"},
-					TargetLabel:  "abc",
-					Action:       relabel.DropEqual,
-					Regex:        relabel.DefaultRelabelConfig.Regex,
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Separator:    relabel.DefaultRelabelConfig.Separator,
+					SourceLabels:         model.LabelNames{"foo"},
+					TargetLabel:          "abc",
+					Action:               relabel.DropEqual,
+					Regex:                relabel.DefaultRelabelConfig.Regex,
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Separator:            relabel.DefaultRelabelConfig.Separator,
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 		},
@@ -377,54 +387,61 @@ var expectedConf = &Config{
 
 			RelabelConfigs: []*relabel.Config{
 				{
-					SourceLabels: model.LabelNames{"job"},
-					Regex:        relabel.MustNewRegexp("(.*)some-[regex]"),
-					Separator:    ";",
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Action:       relabel.Drop,
+					SourceLabels:         model.LabelNames{"job"},
+					Regex:                relabel.MustNewRegexp("(.*)some-[regex]"),
+					Separator:            ";",
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.Drop,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					SourceLabels: model.LabelNames{"__address__"},
-					TargetLabel:  "__tmp_hash",
-					Regex:        relabel.DefaultRelabelConfig.Regex,
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Modulus:      8,
-					Separator:    ";",
-					Action:       relabel.HashMod,
+					SourceLabels:         model.LabelNames{"__address__"},
+					TargetLabel:          "__tmp_hash",
+					Regex:                relabel.DefaultRelabelConfig.Regex,
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Modulus:              8,
+					Separator:            ";",
+					Action:               relabel.HashMod,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					SourceLabels: model.LabelNames{"__tmp_hash"},
-					Regex:        relabel.MustNewRegexp("1"),
-					Separator:    ";",
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Action:       relabel.Keep,
+					SourceLabels:         model.LabelNames{"__tmp_hash"},
+					Regex:                relabel.MustNewRegexp("1"),
+					Separator:            ";",
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.Keep,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					Regex:       relabel.MustNewRegexp("1"),
-					Separator:   ";",
-					Replacement: relabel.DefaultRelabelConfig.Replacement,
-					Action:      relabel.LabelMap,
+					Regex:                relabel.MustNewRegexp("1"),
+					Separator:            ";",
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.LabelMap,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					Regex:       relabel.MustNewRegexp("d"),
-					Separator:   ";",
-					Replacement: relabel.DefaultRelabelConfig.Replacement,
-					Action:      relabel.LabelDrop,
+					Regex:                relabel.MustNewRegexp("d"),
+					Separator:            ";",
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.LabelDrop,
+					NameValidationScheme: model.UTF8Validation,
 				},
 				{
-					Regex:       relabel.MustNewRegexp("k"),
-					Separator:   ";",
-					Replacement: relabel.DefaultRelabelConfig.Replacement,
-					Action:      relabel.LabelKeep,
+					Regex:                relabel.MustNewRegexp("k"),
+					Separator:            ";",
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.LabelKeep,
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 			MetricRelabelConfigs: []*relabel.Config{
 				{
-					SourceLabels: model.LabelNames{"__name__"},
-					Regex:        relabel.MustNewRegexp("expensive_metric.*"),
-					Separator:    ";",
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Action:       relabel.Drop,
+					SourceLabels:         model.LabelNames{"__name__"},
+					Regex:                relabel.MustNewRegexp("expensive_metric.*"),
+					Separator:            ";",
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Action:               relabel.Drop,
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 		},
@@ -479,12 +496,13 @@ var expectedConf = &Config{
 
 			RelabelConfigs: []*relabel.Config{
 				{
-					SourceLabels: model.LabelNames{"__meta_sd_consul_tags"},
-					Regex:        relabel.MustNewRegexp("label:([^=]+)=([^,]+)"),
-					Separator:    ",",
-					TargetLabel:  "${1}",
-					Replacement:  "${2}",
-					Action:       relabel.Replace,
+					SourceLabels:         model.LabelNames{"__meta_sd_consul_tags"},
+					Regex:                relabel.MustNewRegexp("label:([^=]+)=([^,]+)"),
+					Separator:            ",",
+					TargetLabel:          "${1}",
+					Replacement:          "${2}",
+					Action:               relabel.Replace,
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 		},
@@ -1276,12 +1294,13 @@ var expectedConf = &Config{
 
 			RelabelConfigs: []*relabel.Config{
 				{
-					Action:       relabel.Uppercase,
-					Regex:        relabel.DefaultRelabelConfig.Regex,
-					Replacement:  relabel.DefaultRelabelConfig.Replacement,
-					Separator:    relabel.DefaultRelabelConfig.Separator,
-					SourceLabels: model.LabelNames{"instance"},
-					TargetLabel:  "instance",
+					Action:               relabel.Uppercase,
+					Regex:                relabel.DefaultRelabelConfig.Regex,
+					Replacement:          relabel.DefaultRelabelConfig.Replacement,
+					Separator:            relabel.DefaultRelabelConfig.Separator,
+					SourceLabels:         model.LabelNames{"instance"},
+					TargetLabel:          "instance",
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 
@@ -1953,7 +1972,14 @@ func TestLoadConfig(t *testing.T) {
 	c, err := LoadFile("testdata/conf.good.yml", false, promslog.NewNopLogger())
 
 	require.NoError(t, err)
-	require.Equal(t, expectedConf, c)
+	testutil.RequireEqualWithOptions(t, expectedConf, c, []cmp.Option{
+		cmpopts.IgnoreUnexported(config.ProxyConfig{}),
+		cmpopts.IgnoreUnexported(ionos.SDConfig{}),
+		cmpopts.IgnoreUnexported(stackit.SDConfig{}),
+		cmpopts.IgnoreUnexported(regexp.Regexp{}),
+		cmpopts.IgnoreUnexported(hetzner.SDConfig{}),
+		cmpopts.IgnoreUnexported(Config{}),
+	})
 }
 
 func TestScrapeIntervalLarger(t *testing.T) {

go.mod

@@ -56,7 +56,7 @@ require (
 	github.com/prometheus/alertmanager v0.28.1
 	github.com/prometheus/client_golang v1.23.0-rc.1
 	github.com/prometheus/client_model v0.6.2
-	github.com/prometheus/common v0.65.1-0.20250703115700-7f8b2a0d32d3
+	github.com/prometheus/common v0.65.1-0.20250801071412-c79a891c6c28
 	github.com/prometheus/common/assets v0.2.0
 	github.com/prometheus/exporter-toolkit v0.14.0
 	github.com/prometheus/sigv4 v0.2.0

go.sum

@@ -452,8 +452,8 @@ github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNw
 github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
 github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
 github.com/prometheus/common v0.9.1/go.mod h1:yhUN8i9wzaXS3w1O07YhxHEBxD+W35wd8bs7vj7HSQ4=
-github.com/prometheus/common v0.65.1-0.20250703115700-7f8b2a0d32d3 h1:R/zO7ombSHCI8bjQusgCMSL+cE669w5/R2upq5WlPD0=
-github.com/prometheus/common v0.65.1-0.20250703115700-7f8b2a0d32d3/go.mod h1:0gZns+BLRQ3V6NdaerOhMbwwRbNh9hkGINtQAsP5GS8=
+github.com/prometheus/common v0.65.1-0.20250801071412-c79a891c6c28 h1:9CaJtf5ZS3GQVCVoslEkJcKSVwiD9aTqwgMpG1n9zQw=
+github.com/prometheus/common v0.65.1-0.20250801071412-c79a891c6c28/go.mod h1:LL3lcZII3UXGO4InbF+BTSsiAAPUBnwFVbp4gBWIMqw=
 github.com/prometheus/common/assets v0.2.0 h1:0P5OrzoHrYBOSM1OigWL3mY8ZvV2N4zIE/5AahrSrfM=
 github.com/prometheus/common/assets v0.2.0/go.mod h1:D17UVUE12bHbim7HzwUvtqm6gwBEaDQ0F+hIGbFbccI=
 github.com/prometheus/exporter-toolkit v0.14.0 h1:NMlswfibpcZZ+H0sZBiTjrA3/aBFHkNZqE+iCj5EmRg=

model/labels/labels_common.go

@@ -53,7 +53,7 @@ func (ls Labels) String() string {
 			b.WriteByte(',')
 			b.WriteByte(' ')
 		}
-		if !model.LabelName(l.Name).IsValidLegacy() {
+		if !model.LegacyValidation.IsValidLabelName(l.Name) {
 			b.Write(strconv.AppendQuote(b.AvailableBuffer(), l.Name))
 		} else {
 			b.WriteString(l.Name)
@@ -106,18 +106,11 @@ func (ls Labels) IsValid(validationScheme model.ValidationScheme) bool {
 		if l.Name == model.MetricNameLabel {
 			// If the default validation scheme has been overridden with legacy mode,
 			// we need to call the special legacy validation checker.
-			if validationScheme == model.LegacyValidation && !model.IsValidLegacyMetricName(string(model.LabelValue(l.Value))) {
-				return strconv.ErrSyntax
-			}
-			if !model.IsValidMetricName(model.LabelValue(l.Value)) {
+			if !validationScheme.IsValidMetricName(l.Value) {
 				return strconv.ErrSyntax
 			}
 		}
-		if validationScheme == model.LegacyValidation {
-			if !model.LabelName(l.Name).IsValidLegacy() || !model.LabelValue(l.Value).IsValid() {
-				return strconv.ErrSyntax
-			}
-		} else if !model.LabelName(l.Name).IsValid() || !model.LabelValue(l.Value).IsValid() {
+		if !validationScheme.IsValidLabelName(l.Name) || !model.LabelValue(l.Value).IsValid() {
 			return strconv.ErrSyntax
 		}
 		return nil

model/relabel/relabel.go

@@ -100,6 +100,8 @@ type Config struct {
 	Replacement string `yaml:"replacement,omitempty" json:"replacement,omitempty"`
 	// Action is the action to be performed for the relabeling.
 	Action Action `yaml:"action,omitempty" json:"action,omitempty"`
+	// NameValidationScheme to use when validating labels.
+	NameValidationScheme model.ValidationScheme `yaml:"-" json:"-"`
 }
 
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
@@ -112,10 +114,10 @@ func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	if c.Regex.Regexp == nil {
 		c.Regex = MustNewRegexp("")
 	}
-	return c.Validate()
+	return nil
 }
 
-func (c *Config) Validate() error {
+func (c *Config) Validate(nameValidationScheme model.ValidationScheme) error {
 	if c.Action == "" {
 		return errors.New("relabel action cannot be empty")
 	}
@@ -125,7 +127,17 @@ func (c *Config) Validate() error {
 	if (c.Action == Replace || c.Action == HashMod || c.Action == Lowercase || c.Action == Uppercase || c.Action == KeepEqual || c.Action == DropEqual) && c.TargetLabel == "" {
 		return fmt.Errorf("relabel configuration for %s action requires 'target_label' value", c.Action)
 	}
-	if c.Action == Replace && !varInRegexTemplate(c.TargetLabel) && !model.LabelName(c.TargetLabel).IsValid() {
+
+	// Relabel config validation scheme matches global if left blank.
+	switch c.NameValidationScheme {
+	case model.LegacyValidation, model.UTF8Validation:
+	case model.UnsetValidation:
+		c.NameValidationScheme = nameValidationScheme
+	default:
+		return fmt.Errorf("unknown relabel config name validation method specified, must be either '', 'legacy' or 'utf8', got %s", c.NameValidationScheme)
+	}
+
+	if c.Action == Replace && !varInRegexTemplate(c.TargetLabel) && !c.NameValidationScheme.IsValidLabelName(c.TargetLabel) {
 		return fmt.Errorf("%q is invalid 'target_label' for %s action", c.TargetLabel, c.Action)
 	}
 
@@ -133,12 +145,12 @@ func (c *Config) Validate() error {
 		// UTF-8 allows ${} characters, so standard validation allow $variables by default.
 		// TODO(bwplotka): Relabelling users cannot put $ and ${<...>} characters in metric names or values.
 		// Design escaping mechanism to allow that, once valid use case appears.
-		return model.LabelName(value).IsValid()
+		return c.NameValidationScheme.IsValidLabelName(value)
 	}
 	if c.Action == Replace && varInRegexTemplate(c.TargetLabel) && !isValidLabelNameWithRegexVarFn(c.TargetLabel) {
 		return fmt.Errorf("%q is invalid 'target_label' for %s action", c.TargetLabel, c.Action)
 	}
-	if (c.Action == Lowercase || c.Action == Uppercase || c.Action == KeepEqual || c.Action == DropEqual) && !model.LabelName(c.TargetLabel).IsValid() {
+	if (c.Action == Lowercase || c.Action == Uppercase || c.Action == KeepEqual || c.Action == DropEqual) && !c.NameValidationScheme.IsValidLabelName(c.TargetLabel) {
 		return fmt.Errorf("%q is invalid 'target_label' for %s action", c.TargetLabel, c.Action)
 	}
 	if (c.Action == Lowercase || c.Action == Uppercase || c.Action == KeepEqual || c.Action == DropEqual) && c.Replacement != DefaultRelabelConfig.Replacement {
@@ -147,7 +159,7 @@ func (c *Config) Validate() error {
 	if c.Action == LabelMap && !isValidLabelNameWithRegexVarFn(c.Replacement) {
 		return fmt.Errorf("%q is invalid 'replacement' for %s action", c.Replacement, c.Action)
 	}
-	if c.Action == HashMod && !model.LabelName(c.TargetLabel).IsValid() {
+	if c.Action == HashMod && !c.NameValidationScheme.IsValidLabelName(c.TargetLabel) {
 		return fmt.Errorf("%q is invalid 'target_label' for %s action", c.TargetLabel, c.Action)
 	}
 
@@ -318,16 +330,16 @@ func relabel(cfg *Config, lb *labels.Builder) (keep bool) {
 		if indexes == nil {
 			break
 		}
-		target := model.LabelName(cfg.Regex.ExpandString([]byte{}, cfg.TargetLabel, val, indexes))
-		if !target.IsValid() {
+		target := string(cfg.Regex.ExpandString([]byte{}, cfg.TargetLabel, val, indexes))
+		if !cfg.NameValidationScheme.IsValidLabelName(target) {
 			break
 		}
 		res := cfg.Regex.ExpandString([]byte{}, cfg.Replacement, val, indexes)
 		if len(res) == 0 {
-			lb.Del(string(target))
+			lb.Del(target)
 			break
 		}
-		lb.Set(string(target), string(res))
+		lb.Set(target, string(res))
 	case Lowercase:
 		lb.Set(cfg.TargetLabel, strings.ToLower(val))
 	case Uppercase:

model/relabel/relabel_test.go

@@ -747,7 +747,8 @@ func TestRelabel(t *testing.T) {
 			if cfg.Replacement == "" {
 				cfg.Replacement = DefaultRelabelConfig.Replacement
 			}
-			require.NoError(t, cfg.Validate())
+			cfg.NameValidationScheme = model.UTF8Validation
+			require.NoError(t, cfg.Validate(model.UTF8Validation))
 		}
 
 		res, keep := Process(test.input, test.relabel...)
@@ -764,59 +765,76 @@ func TestRelabelValidate(t *testing.T) {
 		expected string
 	}{
 		{
-			config:   Config{},
+			config: Config{
+				NameValidationScheme: model.UTF8Validation,
+			},
 			expected: `relabel action cannot be empty`,
 		},
 		{
 			config: Config{
-				Action: Replace,
+				Action:               Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 			expected: `requires 'target_label' value`,
 		},
 		{
 			config: Config{
-				Action: Lowercase,
+				Action:               Lowercase,
+				NameValidationScheme: model.UTF8Validation,
 			},
 			expected: `requires 'target_label' value`,
 		},
 		{
 			config: Config{
-				Action:      Lowercase,
-				Replacement: DefaultRelabelConfig.Replacement,
-				TargetLabel: "${3}", // With UTF-8 naming, this is now a legal relabel rule.
+				Action:               Lowercase,
+				Replacement:          DefaultRelabelConfig.Replacement,
+				TargetLabel:          "${3}", // With UTF-8 naming, this is now a legal relabel rule.
+				NameValidationScheme: model.UTF8Validation,
+			},
+		},
+		{
+			config: Config{
+				Action:               Lowercase,
+				Replacement:          DefaultRelabelConfig.Replacement,
+				TargetLabel:          "${3}", // Fails with legacy validation
+				NameValidationScheme: model.LegacyValidation,
 			},
+			expected: "\"${3}\" is invalid 'target_label' for lowercase action",
 		},
 		{
 			config: Config{
-				SourceLabels: model.LabelNames{"a"},
-				Regex:        MustNewRegexp("some-([^-]+)-([^,]+)"),
-				Action:       Replace,
-				Replacement:  "${1}",
-				TargetLabel:  "${3}",
+				SourceLabels:         model.LabelNames{"a"},
+				Regex:                MustNewRegexp("some-([^-]+)-([^,]+)"),
+				Action:               Replace,
+				Replacement:          "${1}",
+				TargetLabel:          "${3}",
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 		{
 			config: Config{
-				SourceLabels: model.LabelNames{"a"},
-				Regex:        MustNewRegexp("some-([^-]+)-([^,]+)"),
-				Action:       Replace,
-				Replacement:  "${1}",
-				TargetLabel:  "0${3}", // With UTF-8 naming this targets a valid label.
+				SourceLabels:         model.LabelNames{"a"},
+				Regex:                MustNewRegexp("some-([^-]+)-([^,]+)"),
+				Action:               Replace,
+				Replacement:          "${1}",
+				TargetLabel:          "0${3}", // With UTF-8 naming this targets a valid label.
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 		{
 			config: Config{
-				SourceLabels: model.LabelNames{"a"},
-				Regex:        MustNewRegexp("some-([^-]+)-([^,]+)"),
-				Action:       Replace,
-				Replacement:  "${1}",
-				TargetLabel:  "-${3}", // With UTF-8 naming this targets a valid label.
+				SourceLabels:         model.LabelNames{"a"},
+				Regex:                MustNewRegexp("some-([^-]+)-([^,]+)"),
+				Action:               Replace,
+				Replacement:          "${1}",
+				TargetLabel:          "-${3}", // With UTF-8 naming this targets a valid label.
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 	}
 	for i, test := range tests {
 		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			err := test.config.Validate()
+			err := test.config.Validate(model.UTF8Validation)
 			if test.expected == "" {
 				require.NoError(t, err)
 			} else {

model/rulefmt/rulefmt.go

@@ -30,6 +30,7 @@ import (
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/promql/parser"
 	"github.com/prometheus/prometheus/template"
+	"github.com/prometheus/prometheus/util/namevalidationutil"
 )
 
 // Error represents semantic errors on parsing rule groups.
@@ -96,7 +97,12 @@ type ruleGroups struct {
 }
 
 // Validate validates all rules in the rule groups.
-func (g *RuleGroups) Validate(node ruleGroups) (errs []error) {
+func (g *RuleGroups) Validate(node ruleGroups, nameValidationScheme model.ValidationScheme) (errs []error) {
+	if err := namevalidationutil.CheckNameValidationScheme(nameValidationScheme); err != nil {
+		errs = append(errs, err)
+		return
+	}
+
 	set := map[string]struct{}{}
 
 	for j, g := range g.Groups {
@@ -112,7 +118,7 @@ func (g *RuleGroups) Validate(node ruleGroups) (errs []error) {
 		}
 
 		for k, v := range g.Labels {
-			if !model.LabelName(k).IsValid() || k == model.MetricNameLabel {
+			if !nameValidationScheme.IsValidLabelName(k) || k == model.MetricNameLabel {
 				errs = append(
 					errs, fmt.Errorf("invalid label name: %s", k),
 				)
@@ -128,7 +134,7 @@ func (g *RuleGroups) Validate(node ruleGroups) (errs []error) {
 		set[g.Name] = struct{}{}
 
 		for i, r := range g.Rules {
-			for _, node := range r.Validate(node.Groups[j].Rules[i]) {
+			for _, node := range r.Validate(node.Groups[j].Rules[i], nameValidationScheme) {
 				var ruleName string
 				if r.Alert != "" {
 					ruleName = r.Alert
@@ -192,7 +198,7 @@ type RuleNode struct {
 }
 
 // Validate the rule and return a list of encountered errors.
-func (r *Rule) Validate(node RuleNode) (nodes []WrappedError) {
+func (r *Rule) Validate(node RuleNode, nameValidationScheme model.ValidationScheme) (nodes []WrappedError) {
 	if r.Record != "" && r.Alert != "" {
 		nodes = append(nodes, WrappedError{
 			err:     errors.New("only one of 'record' and 'alert' must be set"),
@@ -238,7 +244,7 @@ func (r *Rule) Validate(node RuleNode) (nodes []WrappedError) {
 				node: &node.Record,
 			})
 		}
-		if !model.IsValidMetricName(model.LabelValue(r.Record)) {
+		if !nameValidationScheme.IsValidMetricName(r.Record) {
 			nodes = append(nodes, WrappedError{
 				err:  fmt.Errorf("invalid recording rule name: %s", r.Record),
 				node: &node.Record,
@@ -255,7 +261,7 @@ func (r *Rule) Validate(node RuleNode) (nodes []WrappedError) {
 	}
 
 	for k, v := range r.Labels {
-		if !model.LabelName(k).IsValid() || k == model.MetricNameLabel {
+		if !nameValidationScheme.IsValidLabelName(k) || k == model.MetricNameLabel {
 			nodes = append(nodes, WrappedError{
 				err: fmt.Errorf("invalid label name: %s", k),
 			})
@@ -269,7 +275,7 @@ func (r *Rule) Validate(node RuleNode) (nodes []WrappedError) {
 	}
 
 	for k := range r.Annotations {
-		if !model.LabelName(k).IsValid() {
+		if !nameValidationScheme.IsValidLabelName(k) {
 			nodes = append(nodes, WrappedError{
 				err: fmt.Errorf("invalid annotation name: %s", k),
 			})
@@ -333,7 +339,7 @@ func testTemplateParsing(rl *Rule) (errs []error) {
 }
 
 // Parse parses and validates a set of rules.
-func Parse(content []byte, ignoreUnknownFields bool) (*RuleGroups, []error) {
+func Parse(content []byte, ignoreUnknownFields bool, nameValidationScheme model.ValidationScheme) (*RuleGroups, []error) {
 	var (
 		groups RuleGroups
 		node   ruleGroups
@@ -358,16 +364,16 @@ func Parse(content []byte, ignoreUnknownFields bool) (*RuleGroups, []error) {
 		return nil, errs
 	}
 
-	return &groups, groups.Validate(node)
+	return &groups, groups.Validate(node, nameValidationScheme)
 }
 
 // ParseFile reads and parses rules from a file.
-func ParseFile(file string, ignoreUnknownFields bool) (*RuleGroups, []error) {
+func ParseFile(file string, ignoreUnknownFields bool, nameValidationScheme model.ValidationScheme) (*RuleGroups, []error) {
 	b, err := os.ReadFile(file)
 	if err != nil {
 		return nil, []error{fmt.Errorf("%s: %w", file, err)}
 	}
-	rgs, errs := Parse(b, ignoreUnknownFields)
+	rgs, errs := Parse(b, ignoreUnknownFields, nameValidationScheme)
 	for i := range errs {
 		errs[i] = fmt.Errorf("%s: %w", file, errs[i])
 	}

model/rulefmt/rulefmt_test.go

@@ -19,17 +19,20 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
 	"gopkg.in/yaml.v3"
 )
 
 func TestParseFileSuccess(t *testing.T) {
-	_, errs := ParseFile("testdata/test.yaml", false)
+	_, errs := ParseFile("testdata/test.yaml", false, model.UTF8Validation)
 	require.Empty(t, errs, "unexpected errors parsing file")
 
-	_, errs = ParseFile("testdata/utf-8_lname.good.yaml", false)
+	_, errs = ParseFile("testdata/utf-8_lname.good.yaml", false, model.UTF8Validation)
 	require.Empty(t, errs, "unexpected errors parsing file")
-	_, errs = ParseFile("testdata/utf-8_annotation.good.yaml", false)
+	_, errs = ParseFile("testdata/utf-8_annotation.good.yaml", false, model.UTF8Validation)
+	require.Empty(t, errs, "unexpected errors parsing file")
+	_, errs = ParseFile("testdata/legacy_validation_annotation.good.yaml", false, model.LegacyValidation)
 	require.Empty(t, errs, "unexpected errors parsing file")
 }
 
@@ -38,7 +41,7 @@ func TestParseFileSuccessWithAliases(t *testing.T) {
 /
 sum without(instance) (rate(requests_total[5m]))
 `
-	rgs, errs := ParseFile("testdata/test_aliases.yaml", false)
+	rgs, errs := ParseFile("testdata/test_aliases.yaml", false, model.UTF8Validation)
 	require.Empty(t, errs, "unexpected errors parsing file")
 	for _, rg := range rgs.Groups {
 		require.Equal(t, "HighAlert", rg.Rules[0].Alert)
@@ -62,8 +65,9 @@ sum without(instance) (rate(requests_total[5m]))
 
 func TestParseFileFailure(t *testing.T) {
 	for _, c := range []struct {
-		filename string
-		errMsg   string
+		filename             string
+		errMsg               string
+		nameValidationScheme model.ValidationScheme
 	}{
 		{
 			filename: "duplicate_grp.bad.yaml",
@@ -105,9 +109,17 @@ func TestParseFileFailure(t *testing.T) {
 			filename: "record_and_keep_firing_for.bad.yaml",
 			errMsg:   "invalid field 'keep_firing_for' in recording rule",
 		},
+		{
+			filename:             "legacy_validation_annotation.bad.yaml",
+			nameValidationScheme: model.LegacyValidation,
+			errMsg:               "invalid annotation name: ins-tance",
+		},
 	} {
 		t.Run(c.filename, func(t *testing.T) {
-			_, errs := ParseFile(filepath.Join("testdata", c.filename), false)
+			if c.nameValidationScheme == model.UnsetValidation {
+				c.nameValidationScheme = model.UTF8Validation
+			}
+			_, errs := ParseFile(filepath.Join("testdata", c.filename), false, c.nameValidationScheme)
 			require.NotEmpty(t, errs, "Expected error parsing %s but got none", c.filename)
 			require.ErrorContainsf(t, errs[0], c.errMsg, "Expected error for %s.", c.filename)
 		})
@@ -203,7 +215,7 @@ groups:
 	}
 
 	for _, tst := range tests {
-		rgs, errs := Parse([]byte(tst.ruleString), false)
+		rgs, errs := Parse([]byte(tst.ruleString), false, model.UTF8Validation)
 		require.NotNil(t, rgs, "Rule parsing, rule=\n"+tst.ruleString)
 		passed := (tst.shouldPass && len(errs) == 0) || (!tst.shouldPass && len(errs) > 0)
 		require.True(t, passed, "Rule validation failed, rule=\n"+tst.ruleString)
@@ -230,7 +242,7 @@ groups:
     annotations:
       summary: "Instance {{ $labels.instance }} up"
 `
-	_, errs := Parse([]byte(group), false)
+	_, errs := Parse([]byte(group), false, model.UTF8Validation)
 	require.Len(t, errs, 2, "Expected two errors")
 	var err00 *Error
 	require.ErrorAs(t, errs[0], &err00)

model/rulefmt/testdata/legacy_validation_annotation.bad.yaml

@@ -0,0 +1,7 @@
+groups:
+  - name: yolo
+    rules:
+      - alert: hola
+        expr: 1
+        annotations:
+          ins-tance: localhost

model/rulefmt/testdata/legacy_validation_annotation.good.yaml

@@ -0,0 +1,7 @@
+groups:
+  - name: yolo
+    rules:
+      - alert: hola
+        expr: 1
+        annotations:
+          ins_tance: localhost

model/textparse/protobufparse.go

@@ -428,7 +428,7 @@ func (p *ProtobufParser) Next() (Entry, error) {
 		// We are at the beginning of a metric family. Put only the name
 		// into entryBytes and validate only name, help, and type for now.
 		name := p.dec.GetName()
-		if !model.IsValidMetricName(model.LabelValue(name)) {
+		if !model.UTF8Validation.IsValidMetricName(name) {
 			return EntryInvalid, fmt.Errorf("invalid metric name: %s", name)
 		}
 		if help := p.dec.GetHelp(); !utf8.ValidString(help) {

notifier/manager.go

@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/model"
 	"github.com/prometheus/common/promslog"
 	"github.com/prometheus/common/version"
 
@@ -92,7 +93,7 @@ func do(ctx context.Context, client *http.Client, req *http.Request) (*http.Resp
 }
 
 // NewManager is the manager constructor.
-func NewManager(o *Options, logger *slog.Logger) *Manager {
+func NewManager(o *Options, nameValidationScheme model.ValidationScheme, logger *slog.Logger) *Manager {
 	if o.Do == nil {
 		o.Do = do
 	}
@@ -104,6 +105,14 @@ func NewManager(o *Options, logger *slog.Logger) *Manager {
 		logger = promslog.NewNopLogger()
 	}
 
+	for _, rc := range o.RelabelConfigs {
+		switch rc.NameValidationScheme {
+		case model.LegacyValidation, model.UTF8Validation:
+		default:
+			rc.NameValidationScheme = nameValidationScheme
+		}
+	}
+
 	n := &Manager{
 		queue:         make([]*Alert, 0, o.QueueCapacity),
 		more:          make(chan struct{}, 1),
@@ -133,6 +142,13 @@ func (n *Manager) ApplyConfig(conf *config.Config) error {
 
 	n.opts.ExternalLabels = conf.GlobalConfig.ExternalLabels
 	n.opts.RelabelConfigs = conf.AlertingConfig.AlertRelabelConfigs
+	for i, rc := range n.opts.RelabelConfigs {
+		switch rc.NameValidationScheme {
+		case model.LegacyValidation, model.UTF8Validation:
+		default:
+			n.opts.RelabelConfigs[i].NameValidationScheme = conf.GlobalConfig.MetricNameValidationScheme
+		}
+	}
 
 	amSets := make(map[string]*alertmanagerSet)
 	// configToAlertmanagers maps alertmanager sets for each unique AlertmanagerConfig,

notifier/manager_test.go

@@ -45,7 +45,7 @@ import (
 const maxBatchSize = 256
 
 func TestHandlerNextBatch(t *testing.T) {
-	h := NewManager(&Options{}, nil)
+	h := NewManager(&Options{}, model.UTF8Validation, nil)
 
 	for i := range make([]struct{}, 2*maxBatchSize+1) {
 		h.queue = append(h.queue, &Alert{
@@ -125,7 +125,7 @@ func TestHandlerSendAll(t *testing.T) {
 	defer server2.Close()
 	defer server3.Close()
 
-	h := NewManager(&Options{}, nil)
+	h := NewManager(&Options{}, model.UTF8Validation, nil)
 
 	authClient, _ := config_util.NewClientFromConfig(
 		config_util.HTTPClientConfig{
@@ -235,7 +235,7 @@ func TestHandlerSendAllRemapPerAm(t *testing.T) {
 	defer server2.Close()
 	defer server3.Close()
 
-	h := NewManager(&Options{}, nil)
+	h := NewManager(&Options{}, model.UTF8Validation, nil)
 	h.alertmanagers = make(map[string]*alertmanagerSet)
 
 	am1Cfg := config.DefaultAlertmanagerConfig
@@ -245,9 +245,10 @@ func TestHandlerSendAllRemapPerAm(t *testing.T) {
 	am2Cfg.Timeout = model.Duration(time.Second)
 	am2Cfg.AlertRelabelConfigs = []*relabel.Config{
 		{
-			SourceLabels: model.LabelNames{"alertnamedrop"},
-			Action:       "drop",
-			Regex:        relabel.MustNewRegexp(".+"),
+			SourceLabels:         model.LabelNames{"alertnamedrop"},
+			Action:               "drop",
+			Regex:                relabel.MustNewRegexp(".+"),
+			NameValidationScheme: model.UTF8Validation,
 		},
 	}
 
@@ -255,9 +256,10 @@ func TestHandlerSendAllRemapPerAm(t *testing.T) {
 	am3Cfg.Timeout = model.Duration(time.Second)
 	am3Cfg.AlertRelabelConfigs = []*relabel.Config{
 		{
-			SourceLabels: model.LabelNames{"alertname"},
-			Action:       "drop",
-			Regex:        relabel.MustNewRegexp(".+"),
+			SourceLabels:         model.LabelNames{"alertname"},
+			Action:               "drop",
+			Regex:                relabel.MustNewRegexp(".+"),
+			NameValidationScheme: model.UTF8Validation,
 		},
 	}
 
@@ -374,7 +376,7 @@ func TestCustomDo(t *testing.T) {
 				Body: io.NopCloser(bytes.NewBuffer(nil)),
 			}, nil
 		},
-	}, nil)
+	}, model.UTF8Validation, nil)
 
 	h.sendOne(context.Background(), nil, testURL, []byte(testBody))
 
@@ -388,14 +390,15 @@ func TestExternalLabels(t *testing.T) {
 		ExternalLabels: labels.FromStrings("a", "b"),
 		RelabelConfigs: []*relabel.Config{
 			{
-				SourceLabels: model.LabelNames{"alertname"},
-				TargetLabel:  "a",
-				Action:       "replace",
-				Regex:        relabel.MustNewRegexp("externalrelabelthis"),
-				Replacement:  "c",
+				SourceLabels:         model.LabelNames{"alertname"},
+				TargetLabel:          "a",
+				Action:               "replace",
+				Regex:                relabel.MustNewRegexp("externalrelabelthis"),
+				Replacement:          "c",
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
-	}, nil)
+	}, model.UTF8Validation, nil)
 
 	// This alert should get the external label attached.
 	h.Send(&Alert{
@@ -422,19 +425,21 @@ func TestHandlerRelabel(t *testing.T) {
 		MaxBatchSize:  maxBatchSize,
 		RelabelConfigs: []*relabel.Config{
 			{
-				SourceLabels: model.LabelNames{"alertname"},
-				Action:       "drop",
-				Regex:        relabel.MustNewRegexp("drop"),
+				SourceLabels:         model.LabelNames{"alertname"},
+				Action:               "drop",
+				Regex:                relabel.MustNewRegexp("drop"),
+				NameValidationScheme: model.UTF8Validation,
 			},
 			{
-				SourceLabels: model.LabelNames{"alertname"},
-				TargetLabel:  "alertname",
-				Action:       "replace",
-				Regex:        relabel.MustNewRegexp("rename"),
-				Replacement:  "renamed",
+				SourceLabels:         model.LabelNames{"alertname"},
+				TargetLabel:          "alertname",
+				Action:               "replace",
+				Regex:                relabel.MustNewRegexp("rename"),
+				Replacement:          "renamed",
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
-	}, nil)
+	}, model.UTF8Validation, nil)
 
 	// This alert should be dropped due to the configuration
 	h.Send(&Alert{
@@ -500,6 +505,7 @@ func TestHandlerQueuing(t *testing.T) {
 			QueueCapacity: 3 * maxBatchSize,
 			MaxBatchSize:  maxBatchSize,
 		},
+		model.UTF8Validation,
 		nil,
 	)
 
@@ -606,7 +612,7 @@ func TestReload(t *testing.T) {
 		},
 	}
 
-	n := NewManager(&Options{}, nil)
+	n := NewManager(&Options{}, model.UTF8Validation, nil)
 
 	cfg := &config.Config{}
 	s := `
@@ -653,7 +659,7 @@ func TestDroppedAlertmanagers(t *testing.T) {
 		},
 	}
 
-	n := NewManager(&Options{}, nil)
+	n := NewManager(&Options{}, model.UTF8Validation, nil)
 
 	cfg := &config.Config{}
 	s := `
@@ -766,6 +772,7 @@ func TestHangingNotifier(t *testing.T) {
 		&Options{
 			QueueCapacity: alertsCount,
 		},
+		model.UTF8Validation,
 		nil,
 	)
 	notifier.alertmanagers = make(map[string]*alertmanagerSet)
@@ -883,6 +890,7 @@ func TestStop_DrainingDisabled(t *testing.T) {
 			QueueCapacity:   10,
 			DrainOnShutdown: false,
 		},
+		model.UTF8Validation,
 		nil,
 	)
 
@@ -969,6 +977,7 @@ func TestStop_DrainingEnabled(t *testing.T) {
 			QueueCapacity:   10,
 			DrainOnShutdown: true,
 		},
+		model.UTF8Validation,
 		nil,
 	)
 
@@ -1031,7 +1040,7 @@ func TestApplyConfig(t *testing.T) {
 	}
 	alertmanagerURL := fmt.Sprintf("http://%s/api/v2/alerts", targetURL)
 
-	n := NewManager(&Options{}, nil)
+	n := NewManager(&Options{}, model.UTF8Validation, nil)
 	cfg := &config.Config{}
 	s := `
 alerting:

prompb/io/prometheus/client/decoder.go

@@ -177,6 +177,7 @@ func (m *MetricStreamingDecoder) Label(b scratchBuilder) error {
 // via UnsafeAddBytes method to reuse strings.
 func parseLabel(dAtA []byte, b scratchBuilder) error {
 	var name, value []byte
+	var unsafeName string
 	l := len(dAtA)
 	iNdEx := 0
 	for iNdEx < l {
@@ -236,8 +237,9 @@ func parseLabel(dAtA []byte, b scratchBuilder) error {
 				return io.ErrUnexpectedEOF
 			}
 			name = dAtA[iNdEx:postIndex]
-			if !model.LabelName(name).IsValid() {
-				return fmt.Errorf("invalid label name: %s", name)
+			unsafeName = yoloString(name)
+			if !model.UTF8Validation.IsValidLabelName(unsafeName) {
+				return fmt.Errorf("invalid label name: %s", unsafeName)
 			}
 			iNdEx = postIndex
 		case 2:

promql/engine.go

@@ -1680,7 +1680,7 @@ func (ev *evaluator) eval(ctx context.Context, expr parser.Expr) (parser.Value,
 
 		if e.Op == parser.COUNT_VALUES {
 			valueLabel := e.Param.(*parser.StringLiteral)
-			if !model.LabelName(valueLabel.Val).IsValid() {
+			if !model.UTF8Validation.IsValidLabelName(valueLabel.Val) {
 				ev.errorf("invalid label name %s", valueLabel)
 			}
 			if !e.Without {

promql/functions.go

@@ -1587,7 +1587,7 @@ func (ev *evaluator) evalLabelReplace(ctx context.Context, args parser.Expressio
 	if err != nil {
 		panic(fmt.Errorf("invalid regular expression in label_replace(): %s", regexStr))
 	}
-	if !model.LabelName(dst).IsValid() {
+	if !model.UTF8Validation.IsValidLabelName(dst) {
 		panic(fmt.Errorf("invalid destination label name in label_replace(): %s", dst))
 	}
 
@@ -1635,12 +1635,12 @@ func (ev *evaluator) evalLabelJoin(ctx context.Context, args parser.Expressions)
 	)
 	for i := 3; i < len(args); i++ {
 		src := stringFromArg(args[i])
-		if !model.LabelName(src).IsValid() {
+		if !model.UTF8Validation.IsValidLabelName(src) {
 			panic(fmt.Errorf("invalid source label name in label_join(): %s", src))
 		}
 		srcLabels[i-3] = src
 	}
-	if !model.LabelName(dst).IsValid() {
+	if !model.UTF8Validation.IsValidLabelName(dst) {
 		panic(fmt.Errorf("invalid destination label name in label_join(): %s", dst))
 	}
 

promql/parser/generated_parser.y

@@ -364,14 +364,14 @@ grouping_label_list:
 
 grouping_label  : maybe_label
                         {
-                        if !model.LabelName($1.Val).IsValid() {
+                        if !model.UTF8Validation.IsValidLabelName($1.Val) {
                                 yylex.(*parser).addParseErrf($1.PositionRange(),"invalid label name for grouping: %q", $1.Val)
                         }
                         $$ = $1
                         }
                 | STRING {
                         unquoted := yylex.(*parser).unquoteString($1.Val)
-                        if !model.LabelName(unquoted).IsValid() {
+                        if !model.UTF8Validation.IsValidLabelName(unquoted) {
                                 yylex.(*parser).addParseErrf($1.PositionRange(),"invalid label name for grouping: %q", unquoted)
                         }
                         $$ = $1

promql/parser/generated_parser.y.go

@@ -1317,7 +1317,7 @@ yydefault:
 	case 59:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
-			if !model.LabelName(yyDollar[1].item.Val).IsValid() {
+			if !model.UTF8Validation.IsValidLabelName(yyDollar[1].item.Val) {
 				yylex.(*parser).addParseErrf(yyDollar[1].item.PositionRange(), "invalid label name for grouping: %q", yyDollar[1].item.Val)
 			}
 			yyVAL.item = yyDollar[1].item
@@ -1326,7 +1326,7 @@ yydefault:
 		yyDollar = yyS[yypt-1 : yypt+1]
 		{
 			unquoted := yylex.(*parser).unquoteString(yyDollar[1].item.Val)
-			if !model.LabelName(unquoted).IsValid() {
+			if !model.UTF8Validation.IsValidLabelName(unquoted) {
 				yylex.(*parser).addParseErrf(yyDollar[1].item.PositionRange(), "invalid label name for grouping: %q", unquoted)
 			}
 			yyVAL.item = yyDollar[1].item

promql/parser/printer.go

@@ -100,7 +100,7 @@ func joinLabels(ss []string) string {
 		if i > 0 {
 			b.WriteString(", ")
 		}
-		if !model.IsValidLegacyMetricName(string(model.LabelValue(s))) {
+		if !model.LegacyValidation.IsValidMetricName(s) {
 			b.Write(strconv.AppendQuote(b.AvailableBuffer(), s))
 		} else {
 			b.WriteString(s)

rules/alerting_test.go

@@ -771,15 +771,16 @@ func TestSendAlertsDontAffectActiveAlerts(t *testing.T) {
 		QueueCapacity: 1,
 		RelabelConfigs: []*relabel.Config{
 			{
-				SourceLabels: model.LabelNames{"a1"},
-				Regex:        relabel.MustNewRegexp("(.+)"),
-				TargetLabel:  "a1",
-				Replacement:  "bug",
-				Action:       "replace",
+				SourceLabels:         model.LabelNames{"a1"},
+				Regex:                relabel.MustNewRegexp("(.+)"),
+				TargetLabel:          "a1",
+				Replacement:          "bug",
+				Action:               "replace",
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 	}
-	nm := notifier.NewManager(&opts, promslog.NewNopLogger())
+	nm := notifier.NewManager(&opts, model.UTF8Validation, promslog.NewNopLogger())
 
 	f := SendAlerts(nm, "")
 	notifyFunc := func(ctx context.Context, expr string, alerts ...*Alert) {

rules/manager.go

@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/model"
 	"github.com/prometheus/common/promslog"
 	"golang.org/x/sync/semaphore"
 
@@ -107,6 +108,7 @@ type NotifyFunc func(ctx context.Context, expr string, alerts ...*Alert)
 
 // ManagerOptions bundles options for the Manager.
 type ManagerOptions struct {
+	NameValidationScheme      model.ValidationScheme
 	ExternalURL               *url.URL
 	QueryFunc                 QueryFunc
 	NotifyFunc                NotifyFunc
@@ -135,6 +137,13 @@ type ManagerOptions struct {
 // NewManager returns an implementation of Manager, ready to be started
 // by calling the Run method.
 func NewManager(o *ManagerOptions) *Manager {
+	switch o.NameValidationScheme {
+	case model.UTF8Validation, model.LegacyValidation:
+	case model.UnsetValidation:
+		o.NameValidationScheme = model.UTF8Validation
+	default:
+		panic(fmt.Errorf("unrecognized name validation scheme: %s", o.NameValidationScheme))
+	}
 	if o.Metrics == nil {
 		o.Metrics = NewGroupMetrics(o.Registerer)
 	}
@@ -289,7 +298,7 @@ func (m *Manager) Update(interval time.Duration, files []string, externalLabels
 
 // GroupLoader is responsible for loading rule groups from arbitrary sources and parsing them.
 type GroupLoader interface {
-	Load(identifier string, ignoreUnknownFields bool) (*rulefmt.RuleGroups, []error)
+	Load(identifier string, ignoreUnknownFields bool, nameValidationScheme model.ValidationScheme) (*rulefmt.RuleGroups, []error)
 	Parse(query string) (parser.Expr, error)
 }
 
@@ -297,8 +306,8 @@ type GroupLoader interface {
 // and parser.ParseExpr.
 type FileLoader struct{}
 
-func (FileLoader) Load(identifier string, ignoreUnknownFields bool) (*rulefmt.RuleGroups, []error) {
-	return rulefmt.ParseFile(identifier, ignoreUnknownFields)
+func (FileLoader) Load(identifier string, ignoreUnknownFields bool, nameValidationScheme model.ValidationScheme) (*rulefmt.RuleGroups, []error) {
+	return rulefmt.ParseFile(identifier, ignoreUnknownFields, nameValidationScheme)
 }
 
 func (FileLoader) Parse(query string) (parser.Expr, error) { return parser.ParseExpr(query) }
@@ -312,7 +321,7 @@ func (m *Manager) LoadGroups(
 	shouldRestore := !m.restored || m.restoreNewRuleGroups
 
 	for _, fn := range filenames {
-		rgs, errs := m.opts.GroupLoader.Load(fn, ignoreUnknownFields)
+		rgs, errs := m.opts.GroupLoader.Load(fn, ignoreUnknownFields, m.opts.NameValidationScheme)
 		if errs != nil {
 			return nil, errs
 		}
@@ -582,7 +591,7 @@ func FromMaps(maps ...map[string]string) labels.Labels {
 }
 
 // ParseFiles parses the rule files corresponding to glob patterns.
-func ParseFiles(patterns []string) error {
+func ParseFiles(patterns []string, nameValidationScheme model.ValidationScheme) error {
 	files := map[string]string{}
 	for _, pat := range patterns {
 		fns, err := filepath.Glob(pat)
@@ -602,7 +611,7 @@ func ParseFiles(patterns []string) error {
 		}
 	}
 	for fn, pat := range files {
-		_, errs := rulefmt.ParseFile(fn, false)
+		_, errs := rulefmt.ParseFile(fn, false, nameValidationScheme)
 		if len(errs) > 0 {
 			return fmt.Errorf("parse rules from file %q (pattern: %q): %w", fn, pat, errors.Join(errs...))
 		}

rules/manager_test.go

@@ -810,7 +810,7 @@ func TestUpdate(t *testing.T) {
 	}
 
 	// Groups will be recreated if updated.
-	rgs, errs := rulefmt.ParseFile("fixtures/rules.yaml", false)
+	rgs, errs := rulefmt.ParseFile("fixtures/rules.yaml", false, model.UTF8Validation)
 	require.Empty(t, errs, "file parsing failures")
 
 	tmpFile, err := os.CreateTemp("", "rules.test.*.yaml")
@@ -2552,11 +2552,11 @@ func TestLabels_FromMaps(t *testing.T) {
 
 func TestParseFiles(t *testing.T) {
 	t.Run("good files", func(t *testing.T) {
-		err := ParseFiles([]string{filepath.Join("fixtures", "rules.y*ml")})
+		err := ParseFiles([]string{filepath.Join("fixtures", "rules.y*ml")}, model.UTF8Validation)
 		require.NoError(t, err)
 	})
 	t.Run("bad files", func(t *testing.T) {
-		err := ParseFiles([]string{filepath.Join("fixtures", "invalid_rules.y*ml")})
+		err := ParseFiles([]string{filepath.Join("fixtures", "invalid_rules.y*ml")}, model.UTF8Validation)
 		require.ErrorContains(t, err, "field unexpected_field not found in type rulefmt.Rule")
 	})
 }

scrape/manager_test.go

@@ -188,11 +188,12 @@ func TestPopulateLabels(t *testing.T) {
 				ScrapeTimeout:  model.Duration(time.Second),
 				RelabelConfigs: []*relabel.Config{
 					{
-						Action:       relabel.Replace,
-						Regex:        relabel.MustNewRegexp("(.*)"),
-						SourceLabels: model.LabelNames{"custom"},
-						Replacement:  "${1}",
-						TargetLabel:  string(model.AddressLabel),
+						Action:               relabel.Replace,
+						Regex:                relabel.MustNewRegexp("(.*)"),
+						SourceLabels:         model.LabelNames{"custom"},
+						Replacement:          "${1}",
+						TargetLabel:          string(model.AddressLabel),
+						NameValidationScheme: model.UTF8Validation,
 					},
 				},
 			},
@@ -226,11 +227,12 @@ func TestPopulateLabels(t *testing.T) {
 				ScrapeTimeout:  model.Duration(time.Second),
 				RelabelConfigs: []*relabel.Config{
 					{
-						Action:       relabel.Replace,
-						Regex:        relabel.MustNewRegexp("(.*)"),
-						SourceLabels: model.LabelNames{"custom"},
-						Replacement:  "${1}",
-						TargetLabel:  string(model.AddressLabel),
+						Action:               relabel.Replace,
+						Regex:                relabel.MustNewRegexp("(.*)"),
+						SourceLabels:         model.LabelNames{"custom"},
+						Replacement:          "${1}",
+						TargetLabel:          string(model.AddressLabel),
+						NameValidationScheme: model.UTF8Validation,
 					},
 				},
 			},
@@ -450,6 +452,10 @@ func TestPopulateLabels(t *testing.T) {
 	for _, c := range cases {
 		in := maps.Clone(c.in)
 		lb := labels.NewBuilder(labels.EmptyLabels())
+		c.cfg.MetricNameValidationScheme = model.UTF8Validation
+		for i := range c.cfg.RelabelConfigs {
+			c.cfg.RelabelConfigs[i].NameValidationScheme = model.UTF8Validation
+		}
 		res, err := PopulateLabels(lb, c.cfg, c.in, nil)
 		if c.err != "" {
 			require.EqualError(t, err, c.err)

scrape/scrape.go

@@ -54,6 +54,7 @@ import (
 	"github.com/prometheus/prometheus/model/value"
 	"github.com/prometheus/prometheus/storage"
 	"github.com/prometheus/prometheus/util/logging"
+	"github.com/prometheus/prometheus/util/namevalidationutil"
 	"github.com/prometheus/prometheus/util/pool"
 )
 
@@ -154,6 +155,9 @@ func newScrapePool(cfg *config.ScrapeConfig, app storage.Appendable, offsetSeed
 		return nil, err
 	}
 
+	if err := namevalidationutil.CheckNameValidationScheme(cfg.MetricNameValidationScheme); err != nil {
+		return nil, errors.New("newScrapePool: MetricNameValidationScheme must be set in scrape configuration")
+	}
 	var escapingScheme model.EscapingScheme
 	escapingScheme, err = config.ToEscapingScheme(cfg.MetricNameEscapingScheme, cfg.MetricNameValidationScheme)
 	if err != nil {
@@ -326,6 +330,9 @@ func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
 	sp.config = cfg
 	oldClient := sp.client
 	sp.client = client
+	if err := namevalidationutil.CheckNameValidationScheme(cfg.MetricNameValidationScheme); err != nil {
+		return errors.New("scrapePool.reload: MetricNameValidationScheme must be set in scrape configuration")
+	}
 	sp.validationScheme = cfg.MetricNameValidationScheme
 	var escapingScheme model.EscapingScheme
 	escapingScheme, err = model.ToEscapingScheme(cfg.MetricNameEscapingScheme)

scrape/scrape_test.go

@@ -334,9 +334,10 @@ func TestDroppedTargetsList(t *testing.T) {
 			MetricNameEscapingScheme:   model.AllowUTF8,
 			RelabelConfigs: []*relabel.Config{
 				{
-					Action:       relabel.Drop,
-					Regex:        relabel.MustNewRegexp("dropMe"),
-					SourceLabels: model.LabelNames{"job"},
+					Action:               relabel.Drop,
+					Regex:                relabel.MustNewRegexp("dropMe"),
+					SourceLabels:         model.LabelNames{"job"},
+					NameValidationScheme: model.UTF8Validation,
 				},
 			},
 		}
@@ -1372,10 +1373,11 @@ func TestScrapeLoopFailWithInvalidLabelsAfterRelabel(t *testing.T) {
 		labels: labels.FromStrings("pod_label_invalid_012\xff", "test"),
 	}
 	relabelConfig := []*relabel.Config{{
-		Action:      relabel.LabelMap,
-		Regex:       relabel.MustNewRegexp("pod_label_invalid_(.+)"),
-		Separator:   ";",
-		Replacement: "$1",
+		Action:               relabel.LabelMap,
+		Regex:                relabel.MustNewRegexp("pod_label_invalid_(.+)"),
+		Separator:            ";",
+		Replacement:          "$1",
+		NameValidationScheme: model.UTF8Validation,
 	}}
 	sl := newBasicScrapeLoop(t, ctx, &testScraper{}, s.Appender, 0)
 	sl.sampleMutator = func(l labels.Labels) labels.Labels {
@@ -4188,18 +4190,20 @@ func TestTargetScrapeIntervalAndTimeoutRelabel(t *testing.T) {
 		MetricNameEscapingScheme:   model.AllowUTF8,
 		RelabelConfigs: []*relabel.Config{
 			{
-				SourceLabels: model.LabelNames{model.ScrapeIntervalLabel},
-				Regex:        relabel.MustNewRegexp("2s"),
-				Replacement:  "3s",
-				TargetLabel:  model.ScrapeIntervalLabel,
-				Action:       relabel.Replace,
+				SourceLabels:         model.LabelNames{model.ScrapeIntervalLabel},
+				Regex:                relabel.MustNewRegexp("2s"),
+				Replacement:          "3s",
+				TargetLabel:          model.ScrapeIntervalLabel,
+				Action:               relabel.Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 			{
-				SourceLabels: model.LabelNames{model.ScrapeTimeoutLabel},
-				Regex:        relabel.MustNewRegexp("500ms"),
-				Replacement:  "750ms",
-				TargetLabel:  model.ScrapeTimeoutLabel,
-				Action:       relabel.Replace,
+				SourceLabels:         model.LabelNames{model.ScrapeTimeoutLabel},
+				Regex:                relabel.MustNewRegexp("500ms"),
+				Replacement:          "750ms",
+				TargetLabel:          model.ScrapeTimeoutLabel,
+				Action:               relabel.Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 	}
@@ -4226,20 +4230,22 @@ func TestLeQuantileReLabel(t *testing.T) {
 		JobName: "test",
 		MetricRelabelConfigs: []*relabel.Config{
 			{
-				SourceLabels: model.LabelNames{"le", "__name__"},
-				Regex:        relabel.MustNewRegexp("(\\d+)\\.0+;.*_bucket"),
-				Replacement:  relabel.DefaultRelabelConfig.Replacement,
-				Separator:    relabel.DefaultRelabelConfig.Separator,
-				TargetLabel:  "le",
-				Action:       relabel.Replace,
+				SourceLabels:         model.LabelNames{"le", "__name__"},
+				Regex:                relabel.MustNewRegexp("(\\d+)\\.0+;.*_bucket"),
+				Replacement:          relabel.DefaultRelabelConfig.Replacement,
+				Separator:            relabel.DefaultRelabelConfig.Separator,
+				TargetLabel:          "le",
+				Action:               relabel.Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 			{
-				SourceLabels: model.LabelNames{"quantile"},
-				Regex:        relabel.MustNewRegexp("(\\d+)\\.0+"),
-				Replacement:  relabel.DefaultRelabelConfig.Replacement,
-				Separator:    relabel.DefaultRelabelConfig.Separator,
-				TargetLabel:  "quantile",
-				Action:       relabel.Replace,
+				SourceLabels:         model.LabelNames{"quantile"},
+				Regex:                relabel.MustNewRegexp("(\\d+)\\.0+"),
+				Replacement:          relabel.DefaultRelabelConfig.Replacement,
+				Separator:            relabel.DefaultRelabelConfig.Separator,
+				TargetLabel:          "quantile",
+				Action:               relabel.Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 		SampleLimit:                100,
@@ -4870,18 +4876,20 @@ func TestTypeUnitReLabel(t *testing.T) {
 		JobName: "test",
 		MetricRelabelConfigs: []*relabel.Config{
 			{
-				SourceLabels: model.LabelNames{"__name__"},
-				Regex:        relabel.MustNewRegexp(".*_total$"),
-				Replacement:  "counter",
-				TargetLabel:  "__type__",
-				Action:       relabel.Replace,
+				SourceLabels:         model.LabelNames{"__name__"},
+				Regex:                relabel.MustNewRegexp(".*_total$"),
+				Replacement:          "counter",
+				TargetLabel:          "__type__",
+				Action:               relabel.Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 			{
-				SourceLabels: model.LabelNames{"__name__"},
-				Regex:        relabel.MustNewRegexp(".*_bytes$"),
-				Replacement:  "bytes",
-				TargetLabel:  "__unit__",
-				Action:       relabel.Replace,
+				SourceLabels:         model.LabelNames{"__name__"},
+				Regex:                relabel.MustNewRegexp(".*_bytes$"),
+				Replacement:          "bytes",
+				TargetLabel:          "__unit__",
+				Action:               relabel.Replace,
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 		SampleLimit:                100,
@@ -5491,25 +5499,28 @@ func TestTargetScrapeConfigWithLabels(t *testing.T) {
 				Params:                     url.Values{"param": []string{secondParam}},
 				RelabelConfigs: []*relabel.Config{
 					{
-						Action:       relabel.DefaultRelabelConfig.Action,
-						Regex:        relabel.DefaultRelabelConfig.Regex,
-						SourceLabels: relabel.DefaultRelabelConfig.SourceLabels,
-						TargetLabel:  model.ScrapeTimeoutLabel,
-						Replacement:  expectedTimeoutLabel,
+						Action:               relabel.DefaultRelabelConfig.Action,
+						Regex:                relabel.DefaultRelabelConfig.Regex,
+						SourceLabels:         relabel.DefaultRelabelConfig.SourceLabels,
+						TargetLabel:          model.ScrapeTimeoutLabel,
+						Replacement:          expectedTimeoutLabel,
+						NameValidationScheme: model.UTF8Validation,
 					},
 					{
-						Action:       relabel.DefaultRelabelConfig.Action,
-						Regex:        relabel.DefaultRelabelConfig.Regex,
-						SourceLabels: relabel.DefaultRelabelConfig.SourceLabels,
-						TargetLabel:  paramLabel,
-						Replacement:  expectedParam,
+						Action:               relabel.DefaultRelabelConfig.Action,
+						Regex:                relabel.DefaultRelabelConfig.Regex,
+						SourceLabels:         relabel.DefaultRelabelConfig.SourceLabels,
+						TargetLabel:          paramLabel,
+						Replacement:          expectedParam,
+						NameValidationScheme: model.UTF8Validation,
 					},
 					{
-						Action:       relabel.DefaultRelabelConfig.Action,
-						Regex:        relabel.DefaultRelabelConfig.Regex,
-						SourceLabels: relabel.DefaultRelabelConfig.SourceLabels,
-						TargetLabel:  model.MetricsPathLabel,
-						Replacement:  expectedPath,
+						Action:               relabel.DefaultRelabelConfig.Action,
+						Regex:                relabel.DefaultRelabelConfig.Regex,
+						SourceLabels:         relabel.DefaultRelabelConfig.SourceLabels,
+						TargetLabel:          model.MetricsPathLabel,
+						Replacement:          expectedPath,
+						NameValidationScheme: model.UTF8Validation,
 					},
 				},
 			},

storage/remote/codec.go

@@ -766,10 +766,10 @@ func (it *chunkedSeriesIterator) Err() error {
 // also making sure that there are no labels with duplicate names.
 func validateLabelsAndMetricName(ls []prompb.Label) error {
 	for i, l := range ls {
-		if l.Name == labels.MetricName && !model.IsValidMetricName(model.LabelValue(l.Value)) {
+		if l.Name == labels.MetricName && !model.UTF8Validation.IsValidMetricName(l.Value) {
 			return fmt.Errorf("invalid metric name: %v", l.Value)
 		}
-		if !model.LabelName(l.Name).IsValid() {
+		if !model.UTF8Validation.IsValidLabelName(l.Name) {
 			return fmt.Errorf("invalid label name: %v", l.Name)
 		}
 		if !model.LabelValue(l.Value).IsValid() {

storage/remote/queue_manager_test.go

@@ -1427,12 +1427,13 @@ func BenchmarkStoreSeries(b *testing.B) {
 		{Name: "replica", Value: "1"},
 	}
 	relabelConfigs := []*relabel.Config{{
-		SourceLabels: model.LabelNames{"namespace"},
-		Separator:    ";",
-		Regex:        relabel.MustNewRegexp("kube.*"),
-		TargetLabel:  "job",
-		Replacement:  "$1",
-		Action:       relabel.Replace,
+		SourceLabels:         model.LabelNames{"namespace"},
+		Separator:            ";",
+		Regex:                relabel.MustNewRegexp("kube.*"),
+		TargetLabel:          "job",
+		Replacement:          "$1",
+		Action:               relabel.Replace,
+		NameValidationScheme: model.UTF8Validation,
 	}}
 	testCases := []struct {
 		name           string

storage/remote/write_test.go

@@ -282,7 +282,8 @@ func TestWriteStorageApplyConfig_PartialUpdate(t *testing.T) {
 		QueueConfig:   config.DefaultQueueConfig,
 		WriteRelabelConfigs: []*relabel.Config{
 			{
-				Regex: relabel.MustNewRegexp(".+"),
+				Regex:                relabel.MustNewRegexp(".+"),
+				NameValidationScheme: model.UTF8Validation,
 			},
 		},
 		ProtobufMessage: config.RemoteWriteProtoMsgV1,
@@ -329,7 +330,10 @@ func TestWriteStorageApplyConfig_PartialUpdate(t *testing.T) {
 
 	storeHashes()
 	// Update c0 and c2.
-	c0.WriteRelabelConfigs[0] = &relabel.Config{Regex: relabel.MustNewRegexp("foo")}
+	c0.WriteRelabelConfigs[0] = &relabel.Config{
+		Regex:                relabel.MustNewRegexp("foo"),
+		NameValidationScheme: model.UTF8Validation,
+	}
 	c2.RemoteTimeout = model.Duration(50 * time.Second)
 	conf = &config.Config{
 		GlobalConfig:       config.GlobalConfig{},

util/namevalidationutil/namevalidationutil.go

@@ -0,0 +1,33 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package namevalidationutil
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/prometheus/common/model"
+)
+
+// CheckNameValidationScheme returns an error iff nameValidationScheme is unset.
+func CheckNameValidationScheme(nameValidationScheme model.ValidationScheme) error {
+	switch nameValidationScheme {
+	case model.UTF8Validation, model.LegacyValidation:
+	case model.UnsetValidation:
+		return errors.New("unset nameValidationScheme")
+	default:
+		panic(fmt.Errorf("unhandled nameValidationScheme: %s", nameValidationScheme.String()))
+	}
+	return nil
+}

util/namevalidationutil/namevalidationutil_test.go

@@ -0,0 +1,30 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package namevalidationutil
+
+import (
+	"testing"
+
+	"github.com/prometheus/common/model"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCheckNameValidationScheme(t *testing.T) {
+	require.NoError(t, CheckNameValidationScheme(model.UTF8Validation))
+	require.NoError(t, CheckNameValidationScheme(model.LegacyValidation))
+	require.EqualError(t, CheckNameValidationScheme(model.UnsetValidation), "unset nameValidationScheme")
+	require.PanicsWithError(t, "unhandled ValidationScheme: 20", func() {
+		CheckNameValidationScheme(20)
+	})
+}

web/api/v1/api.go

@@ -790,8 +790,7 @@ func (api *API) labelValues(r *http.Request) (result apiFuncResult) {
 		name = model.UnescapeName(name, model.ValueEncodingEscaping)
 	}
 
-	label := model.LabelName(name)
-	if !label.IsValid() {
+	if !model.UTF8Validation.IsValidLabelName(name) {
 		return apiFuncResult{nil, &apiError{errorBadData, fmt.Errorf("invalid label name: %q", name)}, nil, nil}
 	}