feat: filter metric value using regex

README.md

@@ -24,6 +24,9 @@ $ curl "http://localhost:7979/probe?module=default&target=http://localhost:8000/
 # HELP example_global_value Example of a top-level global value scrape in the json
 # TYPE example_global_value untyped
 example_global_value{environment="beta",location="planet-mars"} 1234
+# HELP example_regex_value Example of a regex value scrapes in the json
+# TYPE example_regex_value gauge
+example_regex_value{environment="beta"} 1000
 # HELP example_timestamped_value_count Example of a timestamped value scrape in the json
 # TYPE example_timestamped_value_count untyped
 example_timestamped_value_count{environment="beta"} 2

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)
 	}

cmd/main_test.go

@@ -431,3 +431,40 @@ func TestBodyPostQuery(t *testing.T) {
 		target.Close()
 	}
 }
+func TestRegexResponse(t *testing.T) {
+	tests := []struct {
+		name          string
+		ConfigFile    string
+		ServeFile     string
+		ResponseFile  string
+		ShouldSucceed bool
+	}{
+		{"case1_testCorrectResponse", "../test/config/config.yml", "/serve/correctGot.json", "../test/response/expected.txt", true},
+		{"case2_testFailResponse", "../test/config/config.yml", "/serve/failGot.json", "../test/response/expected.txt", false},
+		{"case3_testInvalidRegex", "../test/config/invalidConfig.yml", "/serve/correctGot.json", "../test/response/expected.txt", false},
+		{"case4_testNullVaule", "../test/config/config.yml", "/serve/nullVaule.json", "../test/response/expected.txt", false},
+	}
+
+	target := httptest.NewServer(http.FileServer(http.Dir("../test")))
+	defer target.Close()
+
+	for i, test := range tests {
+		c, err := config.LoadConfig(test.ConfigFile)
+		if err != nil {
+			t.Fatalf("Failed to load config file %s", test.ConfigFile)
+		}
+
+		req := httptest.NewRequest("GET", "http://example.com/foo"+"?module=default&target="+target.URL+test.ServeFile, nil)
+		recorder := httptest.NewRecorder()
+		probeHandler(recorder, req, log.NewNopLogger(), c)
+
+		resp := recorder.Result()
+		body, _ := io.ReadAll(resp.Body)
+
+		expected, _ := os.ReadFile(test.ResponseFile)
+
+		if test.ShouldSucceed && cap(body) != cap(expected) {
+			t.Fatalf("Correct response validation test %d fails unexpectedly.\nGOT:\n%s\nEXPECTED:\n%s", i, body, expected)
+		}
+	}
+}

config/config.go

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

examples/config.yml

@@ -30,6 +30,14 @@ modules:
         active: 1         # static value
         count: '{.count}' # dynamic value
         boolean: '{.some_boolean}'
+    - name: example_regex_value
+      valuetype: gauge
+      help: Example of a regex value scrapes in the json
+      path: '{ .available_memory }'
+      labels:
+        environment: beta # static label
+      regex: ^\d*\.?\d*   # only match digits
+
 
   animals:
     metrics:

examples/data.json

@@ -21,5 +21,6 @@
             "state": "ACTIVE"
         }
     ],
-    "location": "mars"
+    "location": "mars",
+    "available_memory": "1000 MB"
 }

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
+	IncludeRegex           *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.IncludeRegex != nil {
+				if value = m.IncludeRegex.FindString(value); value == "" {
+					level.Error(mc.Logger).Log("msg", fmt.Sprintf("No matching for this pattern '%s'", m.IncludeRegex.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.IncludeRegex != "" {
+				if re, err = regexp.Compile(metric.IncludeRegex); 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,
+				IncludeRegex:           re,
 			}
 			metrics = append(metrics, jsonMetric)
 		case config.ObjectScrape:

test/config/config.yml

@@ -0,0 +1,9 @@
+---
+modules:
+  default:
+    metrics:
+      - name: available_memory
+        path: '{.availableMemory}'
+        help: Available memory in MB
+        valuetype: gauge
+        includeregex: ^\d*\.?\d*  # only match digits

test/config/invalidConfig.yml

@@ -0,0 +1,9 @@
+---
+modules:
+  default:
+    metrics:
+      - name: available_memory
+        path: '{.availableMemory}'
+        help: Available memory in MB
+        valuetype: gauge
+        includeregex: ^\d*\.?\d*)  # Invalid regular expression, parentheses do not match

test/response/expected.txt

@@ -0,0 +1,3 @@
+# HELP available_memory Available memory in MB
+# TYPE available_memory gauge
+available_memory 5

test/serve/correctGot.json

@@ -0,0 +1,3 @@
+{
+    "availableMemory": "5 MB"
+}

test/serve/failGot.json

@@ -0,0 +1,5 @@
+{
+    "availableMemory": "1000 MB",
+    "availableMemory": "  50 GB",
+    "availableMemory": "1.333285ms"
+}

test/serve/nullVaule.json

@@ -0,0 +1,3 @@
+{
+  "availableMemory": ""
+}