gunwokod
commit
8502019852
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package main
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import (
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"flag"
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"time"
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"github.com/golang/glog"
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"golang.org/x/net/html"
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)
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var (
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flagLuftdaten string
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flagScrapeInterval int
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flagListen string
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)
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func init() {
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flag.Set("logtostderr", "true")
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}
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type sensorData struct {
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// Whether the data is fresh.
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stale bool
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// PM2.5 in ug/m3
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pm25 float64
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// PM10 in ug/m3
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pm10 float64
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// Temperature in degrees centigrade
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temperature float64
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// Humidity in percent
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humidity float64
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}
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func getSensorData() (sensorData, error) {
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data := sensorData{}
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resp, err := http.Get(flagLuftdaten)
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if err != nil {
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return data, fmt.Errorf("when GETing data: %v", err)
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}
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root, err := html.Parse(resp.Body)
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if err != nil {
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return data, fmt.Errorf("when parsing HTML: %v", err)
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}
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// Find html.
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htmlN := root.FirstChild
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if htmlN == nil || htmlN.Type != html.ElementNode || htmlN.Data != "html" {
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return data, fmt.Errorf("unexpected root node")
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}
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// Find body.
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bodyN := htmlN.FirstChild.NextSibling
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if bodyN == nil || bodyN.Type != html.ElementNode || bodyN.Data != "body" {
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return data, fmt.Errorf("unexpected html[1] node")
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}
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// Find div class=content
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contentN := bodyN.FirstChild.NextSibling
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if contentN == nil || contentN.Type != html.ElementNode || contentN.Data != "div" || contentN.Attr[0].Key != "class" || contentN.Attr[0].Val != "content" {
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return data, fmt.Errorf("unexpected body[1] node")
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}
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// Find table.
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var tableN *html.Node = nil
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for c := contentN.FirstChild; c != nil; c = c.NextSibling {
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if c.Type == html.ElementNode && c.Data == "table" {
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tableN = c
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break
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}
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}
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if tableN == nil {
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return data, fmt.Errorf("could not find table")
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}
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// Find tbody.
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tbodyN := tableN.FirstChild
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if tbodyN == nil || tbodyN.Type != html.ElementNode || tbodyN.Data != "tbody" {
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return data, fmt.Errorf("unexpected table[0] node")
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}
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got := make(map[string]bool)
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// Iterate throught rows.
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for row := tbodyN.FirstChild; row != nil; row = row.NextSibling {
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td1 := row.FirstChild
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if td1 == nil {
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continue
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}
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td2 := td1.NextSibling
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if td2 == nil {
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continue
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}
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td3 := td2.NextSibling
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if td3 == nil {
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continue
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}
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if td1.Data != "td" || td2.Data != "td" || td3.Data != "td" {
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continue
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}
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if td2.FirstChild.Data == "PM2.5" {
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// This is not an ASCII space.
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parts := strings.Split(td3.FirstChild.Data, " ")
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if len(parts) != 2 {
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continue
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}
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pm25, err := strconv.ParseFloat(parts[0], 64)
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if err != nil {
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continue
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}
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data.pm25 = pm25
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got["PM2.5"] = true
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}
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if td2.FirstChild.Data == "PM10" {
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// This is not an ASCII space.
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parts := strings.Split(td3.FirstChild.Data, " ")
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if len(parts) != 2 {
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continue
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}
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pm10, err := strconv.ParseFloat(parts[0], 64)
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if err != nil {
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continue
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}
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data.pm10 = pm10
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got["PM10"] = true
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}
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if td2.FirstChild.Data == "Temperatur" {
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// This is not an ASCII space.
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parts := strings.Split(td3.FirstChild.Data, " ")
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if len(parts) != 2 {
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continue
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}
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temp, err := strconv.ParseFloat(parts[0], 64)
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if err != nil {
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continue
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}
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data.temperature = temp
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got["Temperature"] = true
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}
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if td2.FirstChild.Data == "rel. Luftfeuchte" {
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// This is not an ASCII space.
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parts := strings.Split(td3.FirstChild.Data, " ")
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if len(parts) != 2 {
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continue
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}
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hum, err := strconv.ParseFloat(parts[0], 64)
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if err != nil {
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continue
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}
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data.humidity = hum
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got["Humidity"] = true
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}
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}
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for _, want := range []string{"PM2.5", "PM10", "Temperature", "Humidity"} {
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if !got[want] {
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return data, fmt.Errorf("could not find %v in HTML", want)
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}
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}
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return data, nil
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}
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func scraper(req chan int, resp chan sensorData) error {
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data := sensorData{
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stale: true,
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}
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feed := func() {
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newData, err := getSensorData()
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if err != nil {
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glog.Error("Could not get sensor data: %v", err)
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data.stale = true
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} else {
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data = newData
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glog.Errorf("Got sensor data: %f/%f/%f/%f", data.pm25, data.pm10, data.temperature, data.humidity)
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}
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}
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feed()
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ticker := time.NewTicker(time.Duration(flagScrapeInterval) * time.Second)
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for {
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select {
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case <-req:
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resp <- data
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case <-ticker.C:
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feed()
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}
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}
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}
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func main() {
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flag.StringVar(&flagLuftdaten, "luftdaten", "http://127.0.0.1:2140/values", "Luftdaten sensor endpoint")
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flag.IntVar(&flagScrapeInterval, "scrape_interval", 60, "Scrape interval of Luftdaten, in seconds")
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flag.StringVar(&flagListen, "listen", "0.0.0.0:2141", "Address to listen at for Prometheus requests")
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flag.Parse()
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glog.Info("Starting scraper...")
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req := make(chan int, 1)
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res := make(chan sensorData, 1)
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go scraper(req, res)
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http.HandleFunc("/metrics", func(w http.ResponseWriter, r *http.Request) {
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req <- 0
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data := <-res
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if data.stale {
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fmt.Fprintf(w, "# data is stale :(\n")
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return
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}
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fmt.Fprintf(w, "# HELP pm25 The current PM2.5 concentration in micrograms per cubic meter\n")
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fmt.Fprintf(w, "# TYPE pm25 gauge\n")
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fmt.Fprintf(w, "pm25 %f\n", data.pm25)
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fmt.Fprintf(w, "# HELP pm10 The current PM10 concentration in micrograms per cubic meter\n")
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fmt.Fprintf(w, "# TYPE pm10 gauge\n")
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fmt.Fprintf(w, "pm10 %f\n", data.pm10)
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fmt.Fprintf(w, "# HELP temperature The current temperature in degrees centigrate\n")
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fmt.Fprintf(w, "# TYPE temperature gauge\n")
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fmt.Fprintf(w, "temperature %f\n", data.temperature)
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fmt.Fprintf(w, "# HELP humidity The current relative humidity in percent\n")
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fmt.Fprintf(w, "# TYPE humidity gauge\n")
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fmt.Fprintf(w, "humidity %f\n", data.humidity)
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})
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http.ListenAndServe(flagListen, nil)
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}
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