Add harcoded namespace to spanmetrics (#540)

* Add harcoded namespace to spanmetrics

* Update changelog

* Specify namespace default in docs

CHANGELOG.md

@@ -7,6 +7,7 @@ cross-compilation issue, but will return in v0.13.0.
 
 - [ENHANCEMENT] Add  `headers` field in `remote_write` config for Tempo. `headers`
   specifies HTTP headers to forward to the remote endpoint. (@alexbiehl)
+- [CHANGE] Add `tempo_spanmetrics` namespace in spanmetrics (@mapno)
 
 - [BUGFIX] Grafana Agent running as a Windows service should start automatically on startup
   (@mattdurham) 

docs/configuration-reference.md

@@ -2074,6 +2074,8 @@ spanmetrics:
   metrics_exporter:
     [ endpoint: <prometheusexporter.endpoint> ]
     [ const_labels: <prometheusexporter.const_labels> ]
+    # Metrics are namespaced to `tempo_spanmetrics` by default.
+    # They can be further namespaced, i.e. `{namespace}_tempo_spanmetrics`
     [ namespace: <prometheusexporter.namespace> ]
     [ send_timestamps: <prometheusexporter.send_timestamps> ]
 ```

pkg/tempo/config.go

@@ -161,8 +161,20 @@ type SpanMetricsConfig struct {
 	LatencyHistogramBuckets []time.Duration                  `yaml:"latency_histogram_buckets,omitempty"`
 	Dimensions              []spanmetricsprocessor.Dimension `yaml:"dimensions,omitempty"`
 
-	// Configuration for Prometheus exporter: https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34/exporter/prometheusexporter/README.md.
-	MetricsExporter map[string]interface{} `yaml:"metrics_exporter,omitempty"`
+	// MetricsExporter is a Prometheus metrics exporter
+	MetricsExporter metricsExporterConfig `yaml:"metrics_exporter,omitempty"`
+}
+
+// Configuration for Prometheus exporter: https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34/exporter/prometheusexporter/README.md.
+type metricsExporterConfig struct {
+	// The address on which the Prometheus scrape handler will be run on.
+	Endpoint string `yaml:"endpoint"`
+	// Namespace if set, exports metrics under the provided value.
+	Namespace string `yaml:"namespace"`
+	// ConstLabels are values that are applied for every exported metric.
+	ConstLabels map[string]interface{} `yaml:"const_labels"`
+	// SendTimestamps will send the underlying scrape timestamp with the export
+	SendTimestamps bool `yaml:"send_timestamps"`
 }
 
 // exporter builds an OTel exporter from RemoteWriteConfig
@@ -300,7 +312,17 @@ func (c *InstanceConfig) otelConfig() (*configmodels.Config, error) {
 
 	if c.SpanMetrics != nil {
 		// Configure the metrics exporter.
-		exporters[defaultSpanMetricsExporter] = c.SpanMetrics.MetricsExporter
+		namespace := "tempo_spanmetrics"
+		if len(c.SpanMetrics.MetricsExporter.Namespace) != 0 {
+			namespace = fmt.Sprintf("%s_%s", c.SpanMetrics.MetricsExporter.Namespace, namespace)
+		}
+
+		exporters[defaultSpanMetricsExporter] = map[string]interface{}{
+			"endpoint":        c.SpanMetrics.MetricsExporter.Endpoint,
+			"namespace":       namespace,
+			"const_labels":    c.SpanMetrics.MetricsExporter.ConstLabels,
+			"send_timestamps": c.SpanMetrics.MetricsExporter.SendTimestamps,
+		}
 
 		processorNames = append(processorNames, "spanmetrics")
 		processors["spanmetrics"] = map[string]interface{}{

pkg/tempo/config_test.go

@@ -465,7 +465,7 @@ exporters:
       max_elapsed_time: 60s
   prometheus:
     endpoint: "0.0.0.0:8889"
-    namespace: promexample
+    namespace: promexample_tempo_spanmetrics
 processors:
   spanmetrics:
     metrics_exporter: prometheus