prometheus.io converter / receive json , parse and set to metrics

prometheus-converter.go

package main
// prometheus receive json and transform to prometheus metrics
// https://groups.google.com/forum/#!topic/prometheus-users/a1ft04aYKNc
import (
	"fmt"
	"net/http"
	"flag"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"strconv"
	"io/ioutil"
	"encoding/json"
)
/*
http://localhost:8081/post
POST:
{
"process":{
"maximumWaitTimeMS":-9223372036854775808,
"totalResponseTimeMS":0,
"maximumResponseTimeMS":-9223372036854775808,
"minimumWaitTimeMS":9223372036854775807,
"averageTimeMS":0,
"totalWaitTimeMS":0,
"lastResponseTimeMS":-1,
"totalRequests":0,
"averageWaitTimeMS":0,
"minimumResponseTimeMS":9223372036854775807
},
"memory":{
"usedMemory":448862416,
"totalMemory":1005060096,
"freeMemory":556197680,
"maxMemory":3817865216
}
}
*/
var (
	//
	addr = flag.String("listen-address", ":8081", "The address to listen on for HTTP requests.")
	// counter
	httpResponsesTotal = prometheus.NewCounterVec(
		prometheus.CounterOpts{
			//Namespace: "testvertical",
			//Subsystem: "http_server",
			Name:      "http_requests_total",
			Help:      "http_requests_total_help",
		},
		[]string{"code", "method"},
	)
	// gauge
	postjson = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Name:      "receivedjson",
			Help:      "the values from the received json",
		},
		[]string{"code", "method"},
	)

)

type WrapHTTPHandler struct {
	handler http.Handler
}

type LoggedResponse struct {
	http.ResponseWriter
	status int
}
// ----  >>  change here  << ----
type PostJson struct {
	Process map[string]interface{} `json:"process"`
	Memory  map[string]interface{} `json:"memory"`

}

func (wrappedHandler *WrapHTTPHandler) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
	loggedWriter := &LoggedResponse{ResponseWriter: writer, status: 200}
	wrappedHandler.handler.ServeHTTP(loggedWriter, request)

	status := strconv.Itoa(loggedWriter.status)
	//log.SetPrefix("[Info]")
	//log.Printf("[RemoteAddr: %s] URL: %s, STATUS: %d, Time Elapsed: %dnanoseconds.\n",
	//	request.RemoteAddr, request.URL, loggedWriter.status, elapsed)

	httpResponsesTotal.WithLabelValues(status, request.Method).Inc()
}

func (loggedResponse *LoggedResponse) WriteHeader(status int) {
	loggedResponse.status = status
	loggedResponse.ResponseWriter.WriteHeader(status)
}

func init() {
	flag.Parse()
	// ----  >>  change here  << ----
	prometheus.MustRegister(httpResponsesTotal)
	prometheus.MustRegister(postjson)
}

func statusHandler(writer http.ResponseWriter, request *http.Request) {
	writer.Write([]byte ("OK"))
}

func mainHandler(writer http.ResponseWriter, request *http.Request) {
	// The "/" pattern matches everything, so we need to check that we're at the root here.
	if request.URL.Path != "/" {
		http.NotFound(writer, request)
		return
	}
	fmt.Fprintf(writer, "home page.")
}


func postJson(rw http.ResponseWriter, req *http.Request) {

	body, err := ioutil.ReadAll(req.Body)
	if err != nil {
		//panic(err)
		http.Error(rw, err.Error(), http.StatusBadRequest)
	}
	//log.Println(string(body))
	var t PostJson
	err = json.Unmarshal(body, &t)
	if err != nil {
		//panic(err)
		http.Error(rw, err.Error(), http.StatusBadRequest)
	}
	// ----  >>  change here  << ----
	for k, v :=range t.Process {
		fmt.Println(k , v)
		postjson.WithLabelValues("process",fmt.Sprintf("%s", k)).
			Set(v.(float64))
	}

	for k, v :=range t.Memory {
		fmt.Println(k , v)
		postjson.WithLabelValues("memory",fmt.Sprintf("%s", k)).
			Set(v.(float64))

	}
}

func main() {

	http.HandleFunc("/", mainHandler)
	http.Handle("/metrics", promhttp.Handler())
	http.HandleFunc("/post", postJson)
	http.HandleFunc("/live", statusHandler)
	http.HandleFunc("/ready", statusHandler)
	http.ListenAndServe(*addr, &WrapHTTPHandler{http.DefaultServeMux})

}

prometheus-converter.json

{
  "process":{
    "maximumWaitTimeMS":-9223372036854775808,
    "totalResponseTimeMS":0,
    "maximumResponseTimeMS":-9223372036854775808,
    "minimumWaitTimeMS":9223372036854775807,
    "averageTimeMS":0,
    "totalWaitTimeMS":0,
    "lastResponseTimeMS":-1,
    "totalRequests":0,
    "averageWaitTimeMS":0,
    "minimumResponseTimeMS":9223372036854775807
  },
  "memory":{
    "usedMemory":448862416,
    "totalMemory":1005060096,
    "freeMemory":556197680,
    "maxMemory":3817865216
  }
}