Scaling option for values

Readme.md

@@ -186,6 +186,8 @@ metrics:
  - prom_name: humidity
  # The name of the metric in a MQTT JSON message
  mqtt_name: humidity
+ # The scale of the metric in a MQTT JSON message (mqtt_value : scale = prom_value : 1)
+ mqtt_value_scale: 100
  # The prometheus help text for this metric
  help: DHT22 humidity reading
  # The prometheus type for this metric. Valid values are: "gauge" and "counter"

pkg/config/config.go

@@ -135,6 +135,7 @@ type MetricConfig struct {
  ValueType string `yaml:"type"`
  ConstantLabels map[string]string `yaml:"const_labels"`
  StringValueMapping *StringValueMappingConfig `yaml:"string_value_mapping"`
+ MQTTValueScale float64 `yaml:"mqtt_value_scale"`
 }
 
 // StringValueMappingConfig defines the mapping from string to float

pkg/metrics/parser.go

@@ -94,6 +94,11 @@ func (p *Parser) parseMetric(metricPath string, deviceID string, value interface
  } else {
  return Metric{}, fmt.Errorf("got data with unexpectd type: %T ('%s')", value, value)
  }
+
+ if cfg.MQTTValueScale != 0 {
+ metricValue = metricValue / cfg.MQTTValueScale
+ }
+
  return Metric{
  Description: cfg.PrometheusDescription(),
  Value: metricValue,

pkg/metrics/parser_test.go

@@ -1,11 +1,12 @@
 package metrics
 
 import (
- "github.com/hikhvar/mqtt2prometheus/pkg/config"
- "github.com/prometheus/client_golang/prometheus"
  "reflect"
  "testing"
  "time"
+
+ "github.com/hikhvar/mqtt2prometheus/pkg/config"
+ "github.com/prometheus/client_golang/prometheus"
 )
 
 func TestParser_parseMetric(t *testing.T) {
@@ -50,6 +51,32 @@ func TestParser_parseMetric(t *testing.T) {
  Topic: "",
  },
  },
+ {
+ name: "scaled string value",
+ fields: fields{
+ map[string][]config.MetricConfig{
+ "temperature": []config.MetricConfig{
+ {
+ PrometheusName: "temperature",
+ ValueType: "gauge",
+ MQTTValueScale: 100,
+ },
+ },
+ },
+ },
+ args: args{
+ metricPath: "temperature",
+ deviceID: "dht22",
+ value: "12.6",
+ },
+ want: Metric{
+ Description: prometheus.NewDesc("temperature", "", []string{"sensor", "topic"}, nil),
+ ValueType: prometheus.GaugeValue,
+ Value: 0.126,
+ IngestTime: testNow(),
+ Topic: "",
+ },
+ },
  {
  name: "string value failure",
  fields: fields{
@@ -94,6 +121,58 @@ func TestParser_parseMetric(t *testing.T) {
  Topic: "",
  },
  },
+ {
+ name: "scaled float value",
+ fields: fields{
+ map[string][]config.MetricConfig{
+ "humidity": []config.MetricConfig{
+ {
+ PrometheusName: "humidity",
+ ValueType: "gauge",
+ MQTTValueScale: 100,
+ },
+ },
+ },
+ },
+ args: args{
+ metricPath: "humidity",
+ deviceID: "dht22",
+ value: 12.6,
+ },
+ want: Metric{
+ Description: prometheus.NewDesc("humidity", "", []string{"sensor", "topic"}, nil),
+ ValueType: prometheus.GaugeValue,
+ Value: 0.126,
+ IngestTime: testNow(),
+ Topic: "",
+ },
+ },
+ {
+ name: "negative scaled float value",
+ fields: fields{
+ map[string][]config.MetricConfig{
+ "humidity": []config.MetricConfig{
+ {
+ PrometheusName: "humidity",
+ ValueType: "gauge",
+ MQTTValueScale: -0.5,
+ },
+ },
+ },
+ },
+ args: args{
+ metricPath: "humidity",
+ deviceID: "dht22",
+ value: 12.6,
+ },
+ want: Metric{
+ Description: prometheus.NewDesc("humidity", "", []string{"sensor", "topic"}, nil),
+ ValueType: prometheus.GaugeValue,
+ Value: -25.2,
+ IngestTime: testNow(),
+ Topic: "",
+ },
+ },
  {
  name: "bool value true",
  fields: fields{
@@ -119,6 +198,32 @@ func TestParser_parseMetric(t *testing.T) {
  Topic: "",
  },
  },
+ {
+ name: "scaled bool value",
+ fields: fields{
+ map[string][]config.MetricConfig{
+ "enabled": []config.MetricConfig{
+ {
+ PrometheusName: "enabled",
+ ValueType: "gauge",
+ MQTTValueScale: 2,
+ },
+ },
+ },
+ },
+ args: args{
+ metricPath: "enabled",
+ deviceID: "dht22",
+ value: true,
+ },
+ want: Metric{
+ Description: prometheus.NewDesc("enabled", "", []string{"sensor", "topic"}, nil),
+ ValueType: prometheus.GaugeValue,
+ Value: 0.5,
+ IngestTime: testNow(),
+ Topic: "",
+ },
+ },
  {
  name: "bool value false",
  fields: fields{