Provide old mongod metrics for dbstats (#337)

* Provide old mongod metrics for dbstats

* Fix test case

* Add Changelog

Author: kanakagrawal

CHANGELOG

@@ -1,8 +1,11 @@
+Release 0.20.8
+Improvement PMM-7424: Add dbStats metric
+Improvement         : Add support for compatible mode for dbStats metric to provide old metrics
+
 Release 0.20.7 released 2021-08-10
 
 Improvement         : Upgraded dependencies
 Fixed error PMM-6877: replsetGetStatus error on mongos
-Improvement PMM-7424: Add dbStats metric
 
 Release 0.20.6 released 2021-06-26
 

exporter/dbstats_collector.go

@@ -58,15 +58,15 @@ func (d *dbstatsCollector) Collect(ch chan<- prometheus.Metric) {
 		d.logger.Debugf("$dbStats metrics for %s", db)
 		debugResult(d.logger, dbStats)
 
-		// Since all dbstats will have the same fields, we need to use a metric prefix (db)
-		// to differentiate metrics between different databases. Labels are being set only to make it easier
-		// to filter
-		prefix := "dbstats_" + db
+		prefix := "dbstats"
 
 		labels := d.topologyInfo.baseLabels()
+
+		// Since all dbstats will have the same fields, we need to use a label
+		// to differentiate metrics between different databases.
 		labels["database"] = db
 
-		for _, metric := range makeMetrics(prefix, dbStats, d.topologyInfo.baseLabels(), d.compatibleMode) {
+		for _, metric := range makeMetrics(prefix, dbStats, labels, d.compatibleMode) {
 			ch <- metric
 		}
 	}

exporter/dbstats_collector_test.go

@@ -19,11 +19,11 @@ package exporter
 import (
 	"context"
 	"fmt"
-	"strings"
+	"sort"
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus/testutil"
+	"github.com/percona/exporter_shared/helpers"
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
 	"go.mongodb.org/mongo-driver/bson"
@@ -61,52 +61,41 @@ func TestDBStatsCollector(t *testing.T) {
 		topologyInfo: ti,
 	}
 
-	// The last \n at the end of this string is important
-	expected := strings.NewReader(`
-# HELP mongodb_dbstats_testdb_avgObjSize dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_avgObjSize untyped
-mongodb_dbstats_testdb_avgObjSize 40
-# HELP mongodb_dbstats_testdb_collections dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_collections untyped
-mongodb_dbstats_testdb_collections 3
-# HELP mongodb_dbstats_testdb_dataSize dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_dataSize untyped
-mongodb_dbstats_testdb_dataSize 1200
-# HELP mongodb_dbstats_testdb_indexSize dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_indexSize untyped
-mongodb_dbstats_testdb_indexSize 12288
-# HELP mongodb_dbstats_testdb_indexes dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_indexes untyped
-mongodb_dbstats_testdb_indexes 3
-# HELP mongodb_dbstats_testdb_objects dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_objects untyped
-mongodb_dbstats_testdb_objects 30
-# HELP mongodb_dbstats_testdb_ok dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_ok untyped
-mongodb_dbstats_testdb_ok 1
-# HELP mongodb_dbstats_testdb_storageSize dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_storageSize untyped
-mongodb_dbstats_testdb_storageSize 12288
-# HELP mongodb_dbstats_testdb_views dbstats_testdb.
-# TYPE mongodb_dbstats_testdb_views untyped
-mongodb_dbstats_testdb_views 0` +
-		"\n")
+	expected := []string{
+		"# HELP mongodb_dbstats_collections dbstats.",
+		"# TYPE mongodb_dbstats_collections untyped",
+		"mongodb_dbstats_collections{database=\"testdb\"} 3",
+		"# HELP mongodb_dbstats_dataSize dbstats.",
+		"# TYPE mongodb_dbstats_dataSize untyped",
+		"mongodb_dbstats_dataSize{database=\"testdb\"} 1200",
+		"# HELP mongodb_dbstats_indexSize dbstats.",
+		"# TYPE mongodb_dbstats_indexSize untyped",
+		"mongodb_dbstats_indexSize{database=\"testdb\"} 12288",
+		"# HELP mongodb_dbstats_indexes dbstats.",
+		"# TYPE mongodb_dbstats_indexes untyped",
+		"mongodb_dbstats_indexes{database=\"testdb\"} 3",
+		"# HELP mongodb_dbstats_objects dbstats.",
+		"# TYPE mongodb_dbstats_objects untyped",
+		"mongodb_dbstats_objects{database=\"testdb\"} 30",
+	}
 
-	// Filter metrics for 2 reasons:
-	// 1. The result is huge
-	// 2. We need to check against know values. Don't use metrics that return counters like uptime
-	//    or counters like the number of transactions because they won't return a known value to compare
-	filter := []string{
-		"mongodb_dbstats_testdb_avgObjSize",
-		"mongodb_dbstats_testdb_collections",
-		"mongodb_dbstats_testdb_dataSize",
-		"mongodb_dbstats_testdb_indexSize",
-		"mongodb_dbstats_testdb_indexes",
-		"mongodb_dbstats_testdb_objects",
-		"mongodb_dbstats_testdb_views",
-		"mongodb_dbstats_testdb_storageSize",
-		"mongodb_dbstats_testdb_ok",
+	metrics := helpers.CollectMetrics(c)
+	actualMetrics := helpers.ReadMetrics(metrics)
+	filters := []string{
+		"mongodb_dbstats_collections",
+		"mongodb_dbstats_dataSize",
+		"mongodb_dbstats_indexSize",
+		"mongodb_dbstats_indexes",
+		"mongodb_dbstats_objects",
+	}
+	labels := map[string]string{
+		"database": "testdb",
 	}
-	err := testutil.CollectAndCompare(c, expected, filter...)
-	assert.NoError(t, err)
+	actualMetrics = filterMetricsWithLabels(actualMetrics,
+		filters,
+		labels)
+	actualLines := helpers.Format(helpers.WriteMetrics(actualMetrics))
+	sort.Strings(actualLines)
+	sort.Strings(expected)
+	assert.Equal(t, expected, actualLines)
 }

exporter/utils_test.go

@@ -35,3 +35,27 @@ func getMetricNames(lines []string) map[string]bool {
 
 	return names
 }
+
+func filterMetricsWithLabels(metrics []*helpers.Metric, filters []string, labels map[string]string) []*helpers.Metric {
+	res := make([]*helpers.Metric, 0, len(metrics))
+	for _, m := range metrics {
+		for _, filterName := range filters {
+			if m.Name == filterName {
+				validMetric := true
+				for labelKey, labelValue := range labels {
+					if m.Labels[labelKey] != labelValue {
+						validMetric = false
+
+						break
+					}
+				}
+				if validMetric {
+					res = append(res, m)
+				}
+
+				break
+			}
+		}
+	}
+	return res
+}

exporter/v1_compatibility.go

@@ -592,6 +592,26 @@ func conversions() []conversion {
 			oldName: "mongodb_ss_wt_cache_maximum_bytes_configured",
 			newName: "mongodb_mongod_wiredtiger_cache_max_bytes",
 		},
+		{
+			oldName: "mongodb_mongod_db_collections_total",
+			newName: "mongodb_dbstats_collections",
+		},
+		{
+			oldName: "mongodb_mongod_db_data_size_bytes",
+			newName: "mongodb_dbstats_dataSize",
+		},
+		{
+			oldName: "mongodb_mongod_db_index_size_bytes",
+			newName: "mongodb_dbstats_indexSize",
+		},
+		{
+			oldName: "mongodb_mongod_db_indexes_total",
+			newName: "mongodb_dbstats_indexes",
+		},
+		{
+			oldName: "mongodb_mongod_db_objects_total",
+			newName: "mongodb_dbstats_objects",
+		},
 	}
 }