optional ts in metrics

pkg/config/config.go

@@ -133,6 +133,7 @@ type MetricConfig struct {
 	SensorNameFilter   Regexp                    `yaml:"sensor_name_filter"`
 	Help               string                    `yaml:"help"`
 	ValueType          string                    `yaml:"type"`
+	OmitTimestamp      bool                      `yaml:"omit_timestamp"`
 	ConstantLabels     map[string]string         `yaml:"const_labels"`
 	StringValueMapping *StringValueMappingConfig `yaml:"string_value_mapping"`
 	MQTTValueScale     float64                   `yaml:"mqtt_value_scale"`

pkg/metrics/collector.go

@@ -2,11 +2,12 @@ package metrics
 
 import (
 	"fmt"
+	"time"
+
 	"github.com/hikhvar/mqtt2prometheus/pkg/config"
 	gocache "github.com/patrickmn/go-cache"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.uber.org/zap"
-	"time"
 )
 
 type Collector interface {
@@ -77,7 +78,12 @@ func (c *MemoryCachedCollector) Collect(mc chan<- prometheus.Metric) {
 			device,
 			metric.Topic,
 		)
-		mc <- prometheus.NewMetricWithTimestamp(metric.IngestTime, m)
+
+		if metric.IngestTime.IsZero() {
+			mc <- m
+		} else {
+			mc <- prometheus.NewMetricWithTimestamp(metric.IngestTime, m)
+		}
 
 	}
 }

pkg/metrics/parser.go

@@ -99,10 +99,15 @@ func (p *Parser) parseMetric(metricPath string, deviceID string, value interface
 		metricValue = metricValue * cfg.MQTTValueScale
 	}
 
+	var ingestTime time.Time
+	if !cfg.OmitTimestamp {
+		ingestTime = now()
+	}
+
 	return Metric{
 		Description: cfg.PrometheusDescription(),
 		Value:       metricValue,
 		ValueType:   cfg.PrometheusValueType(),
-		IngestTime:  now(),
+		IngestTime:  ingestTime,
 	}, nil
 }