feat: filter metric value using regex

Author: raedtwj

cmd/main.go

@@ -122,7 +122,7 @@ func probeHandler(w http.ResponseWriter, r *http.Request, logger log.Logger, con
 
 	registry := prometheus.NewPedanticRegistry()
 
-	metrics, err := exporter.CreateMetricsList(config.Modules[module])
+	metrics, err := exporter.CreateMetricsList(config.Modules[module], logger)
 	if err != nil {
 		level.Error(logger).Log("msg", "Failed to create metrics list from config", "err", err)
 	}

config/config.go

@@ -30,6 +30,7 @@ type Metric struct {
 	EpochTimestamp string
 	Help           string
 	Values         map[string]string
+	Regex          string
 }
 
 type ScrapeType string

exporter/collector.go

@@ -16,6 +16,8 @@ package exporter
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
+	"regexp"
 	"time"
 
 	"github.com/go-kit/log"
@@ -39,6 +41,7 @@ type JSONMetric struct {
 	LabelsJSONPaths        []string
 	ValueType              prometheus.ValueType
 	EpochTimestampJSONPath string
+	Regex                  *regexp.Regexp
 }
 
 func (mc JSONMetricCollector) Describe(ch chan<- *prometheus.Desc) {
@@ -56,7 +59,12 @@ func (mc JSONMetricCollector) Collect(ch chan<- prometheus.Metric) {
 				level.Error(mc.Logger).Log("msg", "Failed to extract value for metric", "path", m.KeyJSONPath, "err", err, "metric", m.Desc)
 				continue
 			}
-
+			if m.Regex != nil {
+				if value = m.Regex.FindString(value); value == "" {
+					level.Error(mc.Logger).Log("msg", fmt.Sprintf("No matching for this pattern '%s'", m.Regex.String()))
+					continue
+				}
+			}
 			if floatValue, err := SanitizeValue(value); err == nil {
 				metric := prometheus.MustNewConstMetric(
 					m.Desc,

exporter/util.go

@@ -21,6 +21,7 @@ import (
 	"math"
 	"net/http"
 	"net/url"
+	"regexp"
 	"strconv"
 	"strings"
 	"text/template"
@@ -74,7 +75,7 @@ func SanitizeIntValue(s string) (int64, error) {
 	return value, fmt.Errorf(resultErr)
 }
 
-func CreateMetricsList(c config.Module) ([]JSONMetric, error) {
+func CreateMetricsList(c config.Module, logger log.Logger) ([]JSONMetric, error) {
 	var (
 		metrics   []JSONMetric
 		valueType prometheus.ValueType
@@ -91,10 +92,18 @@ func CreateMetricsList(c config.Module) ([]JSONMetric, error) {
 		switch metric.Type {
 		case config.ValueScrape:
 			var variableLabels, variableLabelsValues []string
+			var err error
+			var re *regexp.Regexp
 			for k, v := range metric.Labels {
 				variableLabels = append(variableLabels, k)
 				variableLabelsValues = append(variableLabelsValues, v)
 			}
+			if metric.Regex != "" {
+				if re, err = regexp.Compile(metric.Regex); err != nil {
+					level.Error(logger).Log("msg", "invalid regex expression", "err", err)
+					continue
+				}
+			}
 			jsonMetric := JSONMetric{
 				Type: config.ValueScrape,
 				Desc: prometheus.NewDesc(
@@ -107,6 +116,7 @@ func CreateMetricsList(c config.Module) ([]JSONMetric, error) {
 				LabelsJSONPaths:        variableLabelsValues,
 				ValueType:              valueType,
 				EpochTimestampJSONPath: metric.EpochTimestamp,
+				Regex:                  re,
 			}
 			metrics = append(metrics, jsonMetric)
 		case config.ObjectScrape: