Apply filters on prometheus 'up' metrics (#16568)

metricbeat/module/prometheus/collector/_meta/docs.asciidoc

@@ -51,12 +51,27 @@ In order to filter out/in metrics one can make use of `metrics_filters.include`
 -------------------------------------------------------------------------------------
 - module: prometheus
   period: 10s
-  hosts: ["localhost:9092"]
+  hosts: ["localhost:9090"]
   metrics_path: /metrics
   metrics_filters:
     include: ["node_filesystem_*"]
-    exclude: ["node_filesystem_device_*", "node_filesystem_readonly"]
+    exclude: ["node_filesystem_device_*"]
 -------------------------------------------------------------------------------------
 
-The configuration above will include only metrics that match `node_filesystem_*` pattern and do not match `node_filesystem_device_*`
-and are not `node_filesystem_readonly` metric.
+The configuration above will include only metrics that match `node_filesystem_*` pattern and do not match `node_filesystem_device_*`.
+
+
+To keep only specific metrics, anchor the start and the end of the regexp of each metric:
+
+- the caret ^ matches the beginning of a text or line,
+- the dollar sign $ matches the end of a text.
+
+[source,yaml]
+-------------------------------------------------------------------------------------
+- module: prometheus
+  period: 10s
+  hosts: ["localhost:9090"]
+  metrics_path: /metrics
+  metrics_filters:
+    include: ["^node_network_net_dev_group$", "^node_network_up$"]
+-------------------------------------------------------------------------------------

metricbeat/module/prometheus/collector/collector.go

@@ -148,6 +148,10 @@ func (m *MetricSet) Fetch(reporter mb.ReporterV2) error {
 }
 
 func (m *MetricSet) addUpEvent(eventList map[string]common.MapStr, up int) {
+	metricName := "up"
+	if m.skipFamilyName(metricName) {
+		return
+	}
 	upPromEvent := PromEvent{
 		labels: common.MapStr{
 			"instance": m.Host(),
@@ -164,6 +168,13 @@ func (m *MetricSet) addUpEvent(eventList map[string]common.MapStr, up int) {
 }
 
 func (m *MetricSet) skipFamily(family *dto.MetricFamily) bool {
+	if family == nil {
+		return false
+	}
+	return m.skipFamilyName(*family.Name)
+}
+
+func (m *MetricSet) skipFamilyName(family string) bool {
 	// example:
 	//	include_metrics:
 	//		- node_*
@@ -173,19 +184,15 @@ func (m *MetricSet) skipFamily(family *dto.MetricFamily) bool {
 	// This would mean that we want to keep only the metrics that start with node_ prefix but
 	// are not related to disk so we exclude node_disk_* metrics from them.
 
-	if family == nil {
-		return true
-	}
-
 	// if include_metrics are defined, check if this metric should be included
 	if len(m.includeMetrics) > 0 {
-		if !matchMetricFamily(*family.Name, m.includeMetrics) {
+		if !matchMetricFamily(family, m.includeMetrics) {
 			return true
 		}
 	}
 	// now exclude the metric if it matches any of the given patterns
 	if len(m.excludeMetrics) > 0 {
-		if matchMetricFamily(*family.Name, m.excludeMetrics) {
+		if matchMetricFamily(family, m.excludeMetrics) {
 			return true
 		}
 	}