[receiver/prometheusremotewrite] validate if scope is already present (#36927)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Continuing the work done in [this
PR](#35656),
addressing a TODO.

---------

Co-authored-by: Arthur Silva Sens <[email protected]>

Author: perebaj

.chloggen/prwreceiver-checkscope.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: receiver/prometheusremotewrite
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Check if Scope is already present comparing with the received labels
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [36927]
+
+# (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:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/prometheusremotewritereceiver/receiver.go

@@ -234,9 +234,26 @@ func addGaugeDatapoints(rm pmetric.ResourceMetrics, ls labels.Labels, ts writev2
 	// In OTel name+type+unit is the unique identifier of a metric and we should not create
 	// a new metric if it already exists.
 
-	// TODO: Check if Scope is already present by comparing labels "otel_scope_name" and "otel_scope_version"
-	// with Scope.Name and Scope.Version. If it is present, we should append to the existing Scope.
-	m := rm.ScopeMetrics().AppendEmpty().Metrics().AppendEmpty().SetEmptyGauge()
+	scopeName := ls.Get("otel_scope_name")
+	scopeVersion := ls.Get("otel_scope_version")
+	// TODO: If the scope version or scope name is empty, get the information from the collector build tags.
+	// More: https://opentelemetry.io/docs/specs/otel/compatibility/prometheus_and_openmetrics/#:~:text=Metrics%20which%20do%20not%20have%20an%20otel_scope_name%20or%20otel_scope_version%20label%20MUST%20be%20assigned%20an%20instrumentation%20scope%20identifying%20the%20entity%20performing%20the%20translation%20from%20Prometheus%20to%20OpenTelemetry%20(e.g.%20the%20collector%E2%80%99s%20prometheus%20receiver)
+
+	// Check if the name and version present in the labels are already present in the ResourceMetrics.
+	// If it is not present, we should create a new ScopeMetrics.
+	// Otherwise, we should append to the existing ScopeMetrics.
+	for j := 0; j < rm.ScopeMetrics().Len(); j++ {
+		scope := rm.ScopeMetrics().At(j)
+		if scopeName == scope.Scope().Name() && scopeVersion == scope.Scope().Version() {
+			addDatapoints(scope.Metrics().AppendEmpty().SetEmptyGauge().DataPoints(), ls, ts)
+			return
+		}
+	}
+
+	scope := rm.ScopeMetrics().AppendEmpty()
+	scope.Scope().SetName(scopeName)
+	scope.Scope().SetVersion(scopeVersion)
+	m := scope.Metrics().AppendEmpty().SetEmptyGauge()
 	addDatapoints(m.DataPoints(), ls, ts)
 }
 

receiver/prometheusremotewritereceiver/receiver_test.go

@@ -143,6 +143,63 @@ func TestTranslateV2(t *testing.T) {
 		expectedMetrics pmetric.Metrics
 		expectedStats   remote.WriteResponseStats
 	}{
+		{
+			name: "duplicated scope name and version",
+			request: &writev2.Request{
+				Symbols: []string{
+					"",
+					"__name__", "test_metric",
+					"job", "service-x/test",
+					"instance", "107cn001",
+					"otel_scope_name", "scope1",
+					"otel_scope_version", "v1",
+					"otel_scope_name", "scope2",
+					"otel_scope_version", "v2",
+					"d", "e",
+					"foo", "bar",
+				},
+				Timeseries: []writev2.TimeSeries{
+					{
+						Metadata:   writev2.Metadata{Type: writev2.Metadata_METRIC_TYPE_GAUGE},
+						LabelsRefs: []uint32{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16}, // Same scope: scope_name: scope1. scope_version v1
+						Samples:    []writev2.Sample{{Value: 1, Timestamp: 1}},
+					},
+					{
+						Metadata:   writev2.Metadata{Type: writev2.Metadata_METRIC_TYPE_GAUGE},
+						LabelsRefs: []uint32{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16}, // Same scope: scope_name: scope1. scope_version v1
+						Samples:    []writev2.Sample{{Value: 2, Timestamp: 2}},
+					},
+					{
+						Metadata:   writev2.Metadata{Type: writev2.Metadata_METRIC_TYPE_GAUGE},
+						LabelsRefs: []uint32{1, 2, 3, 4, 5, 6, 11, 12, 13, 14, 17, 18}, // Different scope: scope_name: scope2. scope_version v2
+						Samples:    []writev2.Sample{{Value: 3, Timestamp: 3}},
+					},
+				},
+			},
+			expectedMetrics: func() pmetric.Metrics {
+				expected := pmetric.NewMetrics()
+				rm1 := expected.ResourceMetrics().AppendEmpty()
+				rmAttributes1 := rm1.Resource().Attributes()
+				rmAttributes1.PutStr("service.namespace", "service-x")
+				rmAttributes1.PutStr("service.name", "test")
+				rmAttributes1.PutStr("service.instance.id", "107cn001")
+				sm1 := rm1.ScopeMetrics().AppendEmpty()
+				sm1.Scope().SetName("scope1")
+				sm1.Scope().SetVersion("v1")
+				sm1Attributes := sm1.Metrics().AppendEmpty().SetEmptyGauge().DataPoints().AppendEmpty().Attributes()
+				sm1Attributes.PutStr("d", "e")
+				sm2Attributes := sm1.Metrics().AppendEmpty().SetEmptyGauge().DataPoints().AppendEmpty().Attributes()
+				sm2Attributes.PutStr("d", "e")
+
+				sm2 := rm1.ScopeMetrics().AppendEmpty()
+				sm2.Scope().SetName("scope2")
+				sm2.Scope().SetVersion("v2")
+				sm3Attributes := sm2.Metrics().AppendEmpty().SetEmptyGauge().DataPoints().AppendEmpty().Attributes()
+				sm3Attributes.PutStr("foo", "bar")
+				return expected
+			}(),
+			expectedStats: remote.WriteResponseStats{},
+		},
 		{
 			name: "missing metric name",
 			request: &writev2.Request{
@@ -185,8 +242,7 @@ func TestTranslateV2(t *testing.T) {
 				sm1Attributes.PutStr("foo", "bar")
 				// Since we don't check "scope_name" and "scope_version", we end up with duplicated scope metrics for repeated series.
 				// TODO: Properly handle scope metrics.
-				sm2 := rm1.ScopeMetrics().AppendEmpty()
-				sm2Attributes := sm2.Metrics().AppendEmpty().SetEmptyGauge().DataPoints().AppendEmpty().Attributes()
+				sm2Attributes := sm1.Metrics().AppendEmpty().SetEmptyGauge().DataPoints().AppendEmpty().Attributes()
 				sm2Attributes.PutStr("d", "e")
 				sm2Attributes.PutStr("foo", "bar")