[cmd/mdatagen] Don't expose empty resource_attributes config section (

#21519)

If no resource_attributes defined in the metadata.yaml file, don't expose the corresponding empty config section and don't render unnecessary resource attributes related code.

.chloggen/mdatagen-dont-expose-empty-resource-attributes.yaml

@@ -0,0 +1,11 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: cmd/mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Don't expose `resource_attributes` user config section if it's empty.
+
+# One or more tracking issues related to the change
+issues: [21519]

cmd/mdatagen/templates/metrics.go.tmpl

@@ -55,12 +55,12 @@ func DefaultMetricsSettings() MetricsSettings {
 	}
 }
 
+{{ if .ResourceAttributes -}}
 // ResourceAttributeSettings provides common settings for a particular resource attribute.
 type ResourceAttributeSettings struct {
 	Enabled bool `mapstructure:"enabled"`
 }
 
-
 // ResourceAttributesSettings provides settings for {{ .Type }} resource attributes.
 type ResourceAttributesSettings struct {
 	{{- range $name, $attr := .ResourceAttributes }}
@@ -77,6 +77,7 @@ func DefaultResourceAttributesSettings() ResourceAttributesSettings {
 		{{- end }}
 	}
 }
+{{- end }}
 
 {{ range $name, $info := .Attributes }}
 {{- if $info.Enum -}}
@@ -187,7 +188,9 @@ func newMetric{{ $name.Render }}(settings MetricSettings) metric{{ $name.Render
 // MetricsBuilderConfig is a structural subset of an otherwise 1-1 copy of metadata.yaml
 type MetricsBuilderConfig struct {
     Metrics MetricsSettings `mapstructure:"metrics"`
+    {{- if .ResourceAttributes }}
     ResourceAttributes ResourceAttributesSettings `mapstructure:"resource_attributes"`
+    {{- end }}
 }
 
 // MetricsBuilder provides an interface for scrapers to report metrics while taking care of all the transformations
@@ -198,7 +201,9 @@ type MetricsBuilder struct {
 	resourceCapacity         int             // maximum observed number of resource attributes.
 	metricsBuffer            pmetric.Metrics   // accumulates metrics data before emitting.
 	buildInfo                component.BuildInfo // contains version information
+	{{- if .ResourceAttributes }}
 	resourceAttributesSettings ResourceAttributesSettings
+	{{- end }}
 	{{- range $name, $metric := .Metrics }}
 	metric{{ $name.Render }} metric{{ $name.Render }}
 	{{- end }}
@@ -217,7 +222,9 @@ func WithStartTime(startTime pcommon.Timestamp) metricBuilderOption {
 func DefaultMetricsBuilderConfig() MetricsBuilderConfig {
    return MetricsBuilderConfig {
         Metrics: DefaultMetricsSettings(),
+        {{- if .ResourceAttributes }}
         ResourceAttributes: DefaultResourceAttributesSettings(),
+        {{- end }}
    }
 }
 
@@ -243,7 +250,9 @@ func NewMetricsBuilder(mbc MetricsBuilderConfig, settings receiver.CreateSetting
 		startTime:                pcommon.NewTimestampFromTime(time.Now()),
 		metricsBuffer:            pmetric.NewMetrics(),
 		buildInfo:                settings.BuildInfo,
+		{{- if .ResourceAttributes }}
 		resourceAttributesSettings: mbc.ResourceAttributes,
+		{{- end }}
 		{{- range $name, $metric := .Metrics }}
 		metric{{ $name.Render }}: newMetric{{ $name.Render }}(mbc.Metrics.{{ $name.Render }}),
 		{{- end }}
@@ -265,7 +274,7 @@ func (mb *MetricsBuilder) updateCapacity(rm pmetric.ResourceMetrics) {
 }
 
 // ResourceMetricsOption applies changes to provided resource metrics.
-type ResourceMetricsOption func(ResourceAttributesSettings, pmetric.ResourceMetrics)
+type ResourceMetricsOption func({{ if .ResourceAttributes }}ResourceAttributesSettings, {{ end }}pmetric.ResourceMetrics)
 
 {{- range $name, $attr := .ResourceAttributes }}
 {{- range $attr.Enum }}
@@ -298,7 +307,7 @@ func With{{ $name.Render }}(val {{ $attr.Type.Primitive }}) ResourceMetricsOptio
 // WithStartTimeOverride overrides start time for all the resource metrics data points.
 // This option should be only used if different start time has to be set on metrics coming from different resources.
 func WithStartTimeOverride(start pcommon.Timestamp) ResourceMetricsOption {
-	return func(ras ResourceAttributesSettings, rm pmetric.ResourceMetrics) {
+	return func({{ if .ResourceAttributes }}_ ResourceAttributesSettings, {{ end }}rm pmetric.ResourceMetrics) {
 		var dps pmetric.NumberDataPointSlice
 		metrics := rm.ScopeMetrics().At(0).Metrics()
 		for i := 0; i < metrics.Len(); i++ {
@@ -335,7 +344,7 @@ func (mb *MetricsBuilder) EmitForResource(rmo ...ResourceMetricsOption) {
 	{{- end }}
 
 	for _, op := range rmo {
-		op(mb.resourceAttributesSettings, rm)
+		op({{ if .ResourceAttributes }}mb.resourceAttributesSettings, {{ end }}rm)
 	}
 	if ils.Metrics().Len() > 0 {
 		mb.updateCapacity(rm)

cmd/mdatagen/templates/testdata/config.yaml.tmpl

@@ -5,19 +5,23 @@ all_set:
     {{ $name }}:
       enabled: true
     {{- end }}
+  {{- if .ResourceAttributes }}
   resource_attributes:
     {{- range $name, $_ := .ResourceAttributes }}
     {{ $name }}:
       enabled: true
     {{- end }}
+  {{- end }}
 none_set:
   metrics:
     {{- range $name, $_ := .Metrics }}
     {{ $name }}:
       enabled: false
     {{- end }}
+  {{- if .ResourceAttributes }}
   resource_attributes:
     {{- range $name, $_ := .ResourceAttributes }}
     {{ $name }}:
       enabled: false
     {{- end }}
+  {{- end }}

receiver/activedirectorydsreceiver/internal/metadata/testdata/config.yaml

@@ -37,7 +37,6 @@ all_set:
       enabled: true
     active_directory.ds.thread.count:
       enabled: true
-  resource_attributes:
 none_set:
   metrics:
     active_directory.ds.bind.rate:
@@ -76,4 +75,3 @@ none_set:
       enabled: false
     active_directory.ds.thread.count:
       enabled: false
-  resource_attributes:

receiver/chronyreceiver/internal/metadata/testdata/config.yaml

@@ -15,7 +15,6 @@ all_set:
       enabled: true
     ntp.time.root_delay:
       enabled: true
-  resource_attributes:
 none_set:
   metrics:
     ntp.frequency.offset:
@@ -32,4 +31,3 @@ none_set:
       enabled: false
     ntp.time.root_delay:
       enabled: false
-  resource_attributes: