Add --strip-settings-suffix flag for prometheus-community#619

Adds --strip-settings-suffix flag to make the fixes for AWS Aurora in prometheus-community#619 opt in for users. It should be safe for all users, but this code should also be unnecessary if AWS fixes their bug.

Signed-off-by: Joe Adams <github@joeadams.io>

README.md

@@ -82,6 +82,9 @@ This will build the docker image as `prometheuscommunity/postgres_exporter:${bra
 * `include-databases`
   A list of databases to only include when autoDiscoverDatabases is enabled.
 
+* `strip-settings-suffix`
+  Whether to strip unit siffixes (i.e. KB) from pg_settings metrics.
+
 * `log.level`
   Set logging level: one of `debug`, `info`, `warn`, `error`.
 

cmd/postgres_exporter/main.go

@@ -43,6 +43,7 @@ var (
 	excludeDatabases       = kingpin.Flag("exclude-databases", "A list of databases to remove when autoDiscoverDatabases is enabled").Default("").Envar("PG_EXPORTER_EXCLUDE_DATABASES").String()
 	includeDatabases       = kingpin.Flag("include-databases", "A list of databases to include when autoDiscoverDatabases is enabled").Default("").Envar("PG_EXPORTER_INCLUDE_DATABASES").String()
 	metricPrefix           = kingpin.Flag("metric-prefix", "A metric prefix can be used to have non-default (not \"pg\") prefixes for each of the metrics").Default("pg").Envar("PG_EXPORTER_METRIC_PREFIX").String()
+	stripSettingsSuffix    = kingpin.Flag("strip-settings-suffix", "Whether to strip unit siffixes (i.e. KB) from pg_settings metrics.").Default("false").Envar("PG_EXPORTER_STRIP_METRICS_SUFFIX").Bool()
 	logger                 = log.NewNopLogger()
 )
 

cmd/postgres_exporter/pg_setting.go

@@ -53,6 +53,10 @@ func querySettings(ch chan<- prometheus.Metric, server *Server) error {
 			return fmt.Errorf("Error retrieving rows on %q: %s %v", server, namespace, err)
 		}
 
+		if *stripSettingsSuffix {
+			s.stripUnitSuffix()
+		}
+
 		ch <- s.metric(server.labels)
 	}
 
@@ -103,7 +107,7 @@ func (s *pgSetting) metric(labels prometheus.Labels) prometheus.Metric {
 // Removes units from any of the setting values.
 // This is mostly because of a irregularity regarding AWS RDS Aurora
 // https://github.com/prometheus-community/postgres_exporter/issues/619
-func (s *pgSetting) sanitizeValue() {
+func (s *pgSetting) stripUnitSuffix() {
 	for _, unit := range settingUnits {
 		if strings.HasSuffix(s.setting, unit) {
 			endPos := len(s.setting) - len(unit) - 1
@@ -116,7 +120,6 @@ func (s *pgSetting) sanitizeValue() {
 // TODO: fix linter override
 // nolint: nakedret
 func (s *pgSetting) normaliseUnit() (val float64, unit string, err error) {
-	s.sanitizeValue()
 
 	val, err = strconv.ParseFloat(s.setting, 64)
 	if err != nil {

cmd/postgres_exporter/pg_setting_test.go

@@ -17,6 +17,8 @@
 package main
 
 import (
+	"testing"
+
 	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
 	. "gopkg.in/check.v1"
@@ -268,3 +270,31 @@ type fixture struct {
 	d string
 	v float64
 }
+
+func Test_pgSetting_sanitizeValue(t *testing.T) {
+	tests := []struct {
+		name    string
+		setting *pgSetting
+		want    string
+	}{
+		{
+			name: "RDS Shared Buffers",
+			setting: &pgSetting{
+				name:      "shared_buffers",
+				setting:   "88413056kB",
+				unit:      "8kB",
+				shortDesc: "Sets the number of shared memory buffers used by the server.",
+				vartype:   "integer",
+			},
+			want: "88413056",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.setting.stripUnitSuffix()
+			if got := tt.setting.setting; got != tt.want {
+				t.Errorf("sanitizeValue() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}