Default for OTLPConfig not computed when otlp unset

What did you do?

I'm enabling otlp receiver with following argument

- '--web.enable-otlp-receiver'

and on purpose unset the otlp config field (to leverage default)

# otlp: 
#   translation_strategy: UnderscoreEscapingWithSuffixes

What did you expect to see?

I still expect the otlp metrics to be translated with underscore as UnderscoreEscapingWithSuffixes should be the default.

What did you see instead? Under which circumstances?

Instead, the default config is not computed, and the strategy is to not translate. Metrics are not translated with underscores.

I think this is due to the fact that the UnmarshalYAML is not called if the field is unset

prometheus/config/config.go

Lines 1530 to 1562 in d9c0ad1

    
           type OTLPConfig struct { 
        
           	PromoteResourceAttributes         []string                  `yaml:"promote_resource_attributes,omitempty"` 
        
           	TranslationStrategy               translationStrategyOption `yaml:"translation_strategy,omitempty"` 
        
           	KeepIdentifyingResourceAttributes bool                      `yaml:"keep_identifying_resource_attributes,omitempty"` 
        
           	ConvertHistogramsToNHCB           bool                      `yaml:"convert_histograms_to_nhcb,omitempty"` 
        
           } 
        
           // UnmarshalYAML implements the yaml.Unmarshaler interface. 
        
           func (c *OTLPConfig) UnmarshalYAML(unmarshal func(interface{}) error) error { 
        
           	*c = DefaultOTLPConfig 
        
           	type plain OTLPConfig 
        
           	if err := unmarshal((*plain)(c)); err != nil { 
        
           		return err 
        
           	} 
        
           	seen := map[string]struct{}{} 
        
           	var err error 
        
           	for i, attr := range c.PromoteResourceAttributes { 
        
           		attr = strings.TrimSpace(attr) 
        
           		if attr == "" { 
        
           			err = errors.Join(err, errors.New("empty promoted OTel resource attribute")) 
        
           			continue 
        
           		} 
        
           		if _, exists := seen[attr]; exists { 
        
           			err = errors.Join(err, fmt.Errorf("duplicated promoted OTel resource attribute %q", attr)) 
        
           			continue 
        
           		} 
        
           		seen[attr] = struct{}{} 
        
           		c.PromoteResourceAttributes[i] = attr 
        
           	} 
        
           	return err 
        
           }

I see that some defaults are computed on parent structure, and this is what should be done for OTLP config here since the enablement of it is not done inside the structure but via an argument

prometheus/config/config.go

Lines 379 to 381 in d9c0ad1

    
           if c.GlobalConfig.isZero() { 
        
           	c.GlobalConfig = DefaultGlobalConfig 
        
           }

System information

No response

Prometheus version

3.4.1

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	type OTLPConfig struct {
	PromoteResourceAttributes []string `yaml:"promote_resource_attributes,omitempty"`
	TranslationStrategy translationStrategyOption `yaml:"translation_strategy,omitempty"`
	KeepIdentifyingResourceAttributes bool `yaml:"keep_identifying_resource_attributes,omitempty"`
	ConvertHistogramsToNHCB bool `yaml:"convert_histograms_to_nhcb,omitempty"`
	}

	// UnmarshalYAML implements the yaml.Unmarshaler interface.
	func (c *OTLPConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
	*c = DefaultOTLPConfig
	type plain OTLPConfig
	if err := unmarshal((*plain)(c)); err != nil {
	return err
	}

	seen := map[string]struct{}{}
	var err error
	for i, attr := range c.PromoteResourceAttributes {
	attr = strings.TrimSpace(attr)
	if attr == "" {
	err = errors.Join(err, errors.New("empty promoted OTel resource attribute"))
	continue
	}
	if _, exists := seen[attr]; exists {
	err = errors.Join(err, fmt.Errorf("duplicated promoted OTel resource attribute %q", attr))
	continue
	}

	seen[attr] = struct{}{}
	c.PromoteResourceAttributes[i] = attr
	}
	return err
	}

	if c.GlobalConfig.isZero() {
	c.GlobalConfig = DefaultGlobalConfig
	}

Description

What did you do?

What did you expect to see?

What did you see instead? Under which circumstances?

System information

Prometheus version

Prometheus configuration file

Alertmanager version

Alertmanager configuration file

Logs

Metadata

Metadata

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Development

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