[OTEL-2048] Add otelcol_ prefix to internal metrics from trace agent (#…

…387)

* [OTEL-2048] Add otelcol_ prefix to internal metrics from trace agent

* changelog

* Update .chloggen/agent-metrics-prefix.yaml

* fmt

.chloggen/agent-metrics-prefix.yaml

@@ -0,0 +1,16 @@
+# 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 `otelcol_` prefix to internal metrics from trace agent"
+
+# The PR related to this change
+issues: [387]
+
+# (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:

pkg/otlp/metrics/metrics_remapping.go

@@ -37,10 +37,11 @@ func remapMetrics(all pmetric.MetricSlice, m pmetric.Metric) {
 	remapJvmMetrics(all, m)
 }
 
-// renameMetrics adds the `otel.` prefix to metrics.
+// renameMetrics adds the `otel.` or `otelcol_` prefix to metrics.
 func renameMetrics(m pmetric.Metric) {
 	renameHostMetrics(m)
 	renameKafkaMetrics(m)
+	renameAgentInternalOTelMetric(m)
 }
 
 // remapSystemMetrics extracts system metrics from m and appends them to all.
@@ -237,3 +238,24 @@ func renameHostMetrics(m pmetric.Metric) {
 		m.SetName("otel." + m.Name())
 	}
 }
+
+var agentHTTPMetrics = map[string]struct{}{
+	"http_server_duration":      {},
+	"http_server_request_size":  {},
+	"http_server_response_size": {},
+}
+
+// isAgentInternalOTelMetric determines whether a metric is a internal metric in Agent on OTLP
+func isAgentInternalOTelMetric(name string) bool {
+	if _, ok := agentHTTPMetrics[name]; ok {
+		return true
+	}
+	return strings.HasPrefix(name, "datadog_trace_agent") || strings.HasPrefix(name, "datadog_otlp")
+}
+
+// renameAgentInternalOTelMetric adds prefix to internal metrics in Agent on OTLP
+func renameAgentInternalOTelMetric(m pmetric.Metric) {
+	if isAgentInternalOTelMetric(m.Name()) {
+		m.SetName("otelcol_" + m.Name())
+	}
+}