[pkg/otlp/metrics] Add WithSplatArrayAttributes

.chloggen/mx-psi_splat-tags.yaml

@@ -0,0 +1,17 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component (e.g. pkg/quantile)
+component: pkg/otlp/metrics
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add `WithSplatArrayAttributes` translator option
+
+# The PR related to this change
+issues: [329]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+   - This option destructures an array valued attribute into multiple tags with the same key and different values.

.chloggen/mx-psi_splat-tags2.yaml

@@ -0,0 +1,17 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component (e.g. pkg/quantile)
+component: pkg/otlp/metrics
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add `splat` option to `WithAttributeMap`
+
+# The PR related to this change
+issues: [329]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+   - This option destructures an array valued attribute into multiple tags with the same key and different values.

pkg/otlp/metrics/config.go

@@ -29,6 +29,7 @@ type translatorConfig struct {
 	InitialCumulMonoValueMode            InitialCumulMonoValueMode
 	InstrumentationLibraryMetadataAsTags bool
 	InstrumentationScopeMetadataAsTags   bool
+	SplatArrayAttributes                 bool
 
 	originProduct OriginProduct
 
@@ -215,3 +216,11 @@ func WithInitialCumulMonoValueMode(mode InitialCumulMonoValueMode) TranslatorOpt
 		return nil
 	}
 }
+
+// WithSplatArrayAttributes destructures an array attribute into multiple Datadog tags.
+func WithSplatArrayAttributes() TranslatorOption {
+	return func(t *translatorConfig) error {
+		t.SplatArrayAttributes = true
+		return nil
+	}
+}

pkg/otlp/metrics/dimensions.go

@@ -80,14 +80,38 @@ func (d *Dimensions) OriginProductDetail() OriginProductDetail {
 // getTags maps an attributeMap into a slice of Datadog tags
 func getTags(labels pcommon.Map) []string {
 	tags := make([]string, 0, labels.Len())
-	labels.Range(func(key string, value pcommon.Value) bool {
-		v := value.AsString()
+	labels.Range(func(key string, val pcommon.Value) bool {
+		v := val.AsString()
 		tags = append(tags, utils.FormatKeyValueTag(key, v))
 		return true
 	})
 	return tags
 }
 
+// getTagsWithSplat maps an attributeMap into a slice of Datadog tags.
+// It will flatten the map values if they are slices.
+func getTagsWithSplat(labels pcommon.Map) []string {
+	// Allocation is a lower bound since we are not traversing the whole map.
+	tags := make([]string, 0, labels.Len())
+
+	var addToTags func(string, pcommon.Value) bool
+	addToTags = func(key string, val pcommon.Value) bool {
+		switch val.Type() {
+		case pcommon.ValueTypeSlice:
+			for i := 0; i < val.Slice().Len(); i++ {
+				_ = addToTags(key, val.Slice().At(i))
+			}
+		default:
+			v := val.AsString()
+			tags = append(tags, utils.FormatKeyValueTag(key, v))
+		}
+		return true
+	}
+
+	labels.Range(addToTags)
+	return tags
+}
+
 // AddTags to metrics dimensions.
 func (d *Dimensions) AddTags(tags ...string) *Dimensions {
 	// defensively copy the tags
@@ -106,7 +130,10 @@ func (d *Dimensions) AddTags(tags ...string) *Dimensions {
 }
 
 // WithAttributeMap creates a new metricDimensions struct with additional tags from attributes.
-func (d *Dimensions) WithAttributeMap(labels pcommon.Map) *Dimensions {
+func (d *Dimensions) WithAttributeMap(labels pcommon.Map, splat bool) *Dimensions {
+	if splat {
+		return d.AddTags(getTagsWithSplat(labels)...)
+	}
 	return d.AddTags(getTags(labels)...)
 }
 

pkg/otlp/metrics/dimensions_test.go

@@ -27,12 +27,41 @@ func TestWithAttributeMap(t *testing.T) {
 		"key1": "val1",
 		"key2": "val2",
 		"key3": "",
+		"key4": []any{"val4a", "val4b"},
+		"key5": []any{"val5a", []any{"val5b", "val5c", []any{"val5d"}}},
 	})
 
 	dims := Dimensions{}
 	assert.ElementsMatch(t,
-		dims.WithAttributeMap(attributes).tags,
-		[...]string{"key1:val1", "key2:val2", "key3:n/a"},
+		dims.WithAttributeMap(attributes, false).tags,
+		[...]string{"key1:val1", "key2:val2", "key3:n/a", `key4:["val4a","val4b"]`, `key5:["val5a",["val5b","val5c",["val5d"]]]`},
+	)
+}
+
+func TestWithAttributeMapSplat(t *testing.T) {
+	attributes := pcommon.NewMap()
+	attributes.FromRaw(map[string]interface{}{
+		"key1": "val1",
+		"key2": "val2",
+		"key3": "",
+		"key4": []any{"val4a", "val4b"},
+		"key5": []any{"val5a", []any{"val5b", "val5c", []any{"val5d"}}},
+	})
+
+	dims := Dimensions{}
+	assert.ElementsMatch(t,
+		dims.WithAttributeMap(attributes, true).tags,
+		[...]string{
+			"key1:val1",
+			"key2:val2",
+			"key3:n/a",
+			"key4:val4a",
+			"key4:val4b",
+			"key5:val5a",
+			"key5:val5b",
+			"key5:val5c",
+			"key5:val5d",
+		},
 	)
 }
 
@@ -115,7 +144,7 @@ func TestAllFieldsAreCopied(t *testing.T) {
 	newDims := dims.
 		AddTags("tagThree:c").
 		WithSuffix("suffix").
-		WithAttributeMap(attributes)
+		WithAttributeMap(attributes, false)
 
 	assert.Equal(t, "example.name.suffix", newDims.Name())
 	assert.Equal(t, "hostname", newDims.Host())

pkg/otlp/metrics/exponential_histograms_translator.go

@@ -93,7 +93,7 @@ func (t *Translator) mapExponentialHistogramMetrics(
 		p := slice.At(i)
 		startTs := uint64(p.StartTimestamp())
 		ts := uint64(p.Timestamp())
-		pointDims := dims.WithAttributeMap(p.Attributes())
+		pointDims := dims.WithAttributeMap(p.Attributes(), t.cfg.SplatArrayAttributes)
 
 		histInfo := histogramInfo{ok: true}
 

pkg/otlp/metrics/metrics_translator.go

@@ -156,7 +156,7 @@ func (t *Translator) mapNumberMetrics(
 			continue
 		}
 
-		pointDims := dims.WithAttributeMap(p.Attributes())
+		pointDims := dims.WithAttributeMap(p.Attributes(), t.cfg.SplatArrayAttributes)
 		var val float64
 		switch p.ValueType() {
 		case pmetric.NumberDataPointValueTypeDouble:
@@ -215,7 +215,7 @@ func (t *Translator) mapNumberMonotonicMetrics(
 
 		ts := uint64(p.Timestamp())
 		startTs := uint64(p.StartTimestamp())
-		pointDims := dims.WithAttributeMap(p.Attributes())
+		pointDims := dims.WithAttributeMap(p.Attributes(), t.cfg.SplatArrayAttributes)
 
 		var val float64
 		switch p.ValueType() {
@@ -467,7 +467,7 @@ func (t *Translator) mapHistogramMetrics(
 
 		startTs := uint64(p.StartTimestamp())
 		ts := uint64(p.Timestamp())
-		pointDims := dims.WithAttributeMap(p.Attributes())
+		pointDims := dims.WithAttributeMap(p.Attributes(), t.cfg.SplatArrayAttributes)
 
 		histInfo := histogramInfo{ok: true}
 
@@ -576,7 +576,7 @@ func (t *Translator) mapSummaryMetrics(
 
 		startTs := uint64(p.StartTimestamp())
 		ts := uint64(p.Timestamp())
-		pointDims := dims.WithAttributeMap(p.Attributes())
+		pointDims := dims.WithAttributeMap(p.Attributes(), t.cfg.SplatArrayAttributes)
 
 		// count and sum are increasing; we treat them as cumulative monotonic sums.
 		{