Sanitize metric type prefixes

stackdriver_exporter.go

@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"slices"
 	"strings"
 
 	"github.com/PuerkitoBio/rehttp"
@@ -303,7 +304,8 @@ func main() {
 
 	level.Info(logger).Log("msg", "Using Google Cloud Project IDs", "projectIDs", fmt.Sprintf("%v", projectIDs))
 
-	metricsTypePrefixes := strings.Split(*monitoringMetricsTypePrefixes, ",")
+	inputPrefixes := strings.Split(*monitoringMetricsTypePrefixes, ",")
+	metricsTypePrefixes := parseMetricTypePrefixes(inputPrefixes)
 	metricExtraFilters := parseMetricExtraFilters()
 
 	if *metricsPath == *stackdriverMetricsPath {
@@ -353,6 +355,39 @@ func main() {
 	}
 }
 
+func parseMetricTypePrefixes(inputPrefixes []string) (metricTypePrefixes []string) {
+	// only keep unique prefixes
+	uniqueKeys := make(map[string]bool)
+	uniquePrefixes := []string{}
+	for _, prefix := range inputPrefixes {
+		if _, ok := uniqueKeys[prefix]; !ok {
+			uniqueKeys[prefix] = true
+			uniquePrefixes = append(uniquePrefixes, prefix)
+		}
+	}
+
+	// drop prefixes that start with another existing prefix to avoid error:
+	// "collected metric xxx was collected before with the same name and label values"
+	slices.Sort(uniquePrefixes)
+	for i, prefix := range uniquePrefixes {
+		if i == 0 {
+			metricTypePrefixes = []string{prefix}
+		} else {
+			previousIndex := len(metricTypePrefixes) - 1
+
+			// current prefix starts with previous one
+			if strings.HasPrefix(prefix, metricTypePrefixes[previousIndex]) {
+				// drop current prefix
+				continue
+			}
+
+			metricTypePrefixes = append(metricTypePrefixes, prefix)
+		}
+	}
+
+	return metricTypePrefixes
+}
+
 func parseMetricExtraFilters() []collectors.MetricFilter {
 	var extraFilters []collectors.MetricFilter
 	for _, ef := range *monitoringMetricsExtraFilter {

stackdriver_exporter_test.go

@@ -0,0 +1,37 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import "testing"
+import "reflect"
+
+func TestParseMetricTypePrefixes(t *testing.T) {
+	inputPrefixes := []string{
+		"redis.googleapis.com/stats/memory/usage",
+		"loadbalancing.googleapis.com/https/request_count",
+		"loadbalancing.googleapis.com",
+		"redis.googleapis.com/stats/memory/usage_ratio",
+		"redis.googleapis.com/stats/memory/usage_ratio",
+	}
+	expectedOutputPrefixes := []string{
+		"loadbalancing.googleapis.com",
+		"redis.googleapis.com/stats/memory/usage",
+	}
+
+	outputPrefixes := parseMetricTypePrefixes(inputPrefixes)
+
+	if !reflect.DeepEqual(outputPrefixes, expectedOutputPrefixes) {
+		t.Errorf("Metric type prefix sanitization did not produce expected output. Expected:\n%s\nGot:\n%s", expectedOutputPrefixes, outputPrefixes)
+	}
+}