Add support for dynamic tag_<name> labels in metrics

README.md

@@ -662,7 +662,7 @@ If you are using `histogram`, its always going to use the `request_time` to obse
 `buckets` type is an array of float64 and its default value is `[1, 2, 5, 7, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 1000, 2000, 5000, 10000, 30000, 60000]`.
 
 The `labels` configuration determines the label name and value extracted from the analytic record.
-The available values are: `["host","method", "path", "response_code", "api_key", "time_stamp", "api_version", "api_name", "api_id", "org_id", "oauth_id", "request_time", "ip_address", "alias"]`
+The available values are: `["host","method", "path", "response_code", "api_key", "time_stamp", "api_version", "api_name", "api_id", "org_id", "oauth_id", "request_time", "ip_address", "alias", "tag_<tag-name>"]`
 
 ###### JSON / Conf File
 

pumps/prometheus.go

@@ -435,7 +435,17 @@ func (pm *PrometheusMetric) GetLabelsValues(decoded analytics.AnalyticsRecord) [
 	}
 
 	for _, label := range pm.Labels {
-		if val, ok := mapping[label]; ok {
+		if strings.HasPrefix(label, "tag_") {
+			tagPrefix := strings.TrimPrefix(label, "tag_") + "-"
+			value := "" // Default value when no tag matches
+			for _, t := range decoded.Tags {
+				if strings.HasPrefix(t, tagPrefix) {
+					value = strings.TrimPrefix(t, tagPrefix)
+					break
+				}
+			}
+			values = append(values, value)
+		} else if val, ok := mapping[label]; ok {
 			values = append(values, fmt.Sprint(val))
 		}
 	}

pumps/prometheus_test.go

@@ -424,6 +424,36 @@ func TestPrometheusGetLabelsValues(t *testing.T) {
 			},
 			expectedLabels: []string{"200", "api_1", "abc"},
 		},
+		{
+			testName: "valid custom tag",
+			customMetric: PrometheusMetric{
+				Name:       "testCounterMetric",
+				MetricType: counterType,
+				Labels:     []string{"tag_custom"},
+			},
+			record: analytics.AnalyticsRecord{
+				APIID:        "api_1",
+				ResponseCode: 200,
+				APIKey:       "apikey",
+				Tags:         []string{"custom-value"},
+			},
+			expectedLabels: []string{"value"},
+		},
+		{
+			testName: "two valid tag labels - one without value",
+			customMetric: PrometheusMetric{
+				Name:       "testCounterMetric",
+				MetricType: counterType,
+				Labels:     []string{"tag_custom", "tag_noexists"},
+			},
+			record: analytics.AnalyticsRecord{
+				APIID:        "api_1",
+				ResponseCode: 200,
+				APIKey:       "apikey",
+				Tags:         []string{"custom-value"},
+			},
+			expectedLabels: []string{"value", ""},
+		},
 	}
 
 	for _, tc := range tcs {