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package main
import (
"flag"
"fmt"
"github.com/gorilla/mux"
"log"
"net/http"
"strconv"
)
var (
metrics map[string]float64
)
func metricsHandler(w http.ResponseWriter, r *http.Request) {
// if the request method is GET, return all metrics
if r.Method == "GET" {
// if the length of the metrics map is zero, return some information on how to add metrics
if len(metrics) == 0 {
returnString := "Add metrics by making a post request to this endpoint\n" +
"curl -X POST --data = \"\" <url>:<port>/meetrics"
_, _ = fmt.Fprintf(w, returnString)
} else {
// return all the metrics
for key, value := range metrics {
_, _ = fmt.Fprintf(w, "%s %f\n", key, value)
}
}
// if the request method is POST, add the posted metrics to the metrics map
} else if r.Method == "POST" {
// parse the POST form
errParseForm := r.ParseForm()
if errParseForm != nil {
panic(errParseForm)
}
// parse the parameters
key := r.Form.Get("key")
value, parseFloatErr := strconv.ParseFloat(r.Form.Get("value"), 64)
if parseFloatErr != nil {
log.Printf("Error parsing %v", value)
}
// if the metrics var does not exist yet, create it
if metrics == nil {
metrics = map[string]float64{}
}
// assign the value to the key
metrics[key] = value
_, _ = fmt.Fprintf(w, "added the metrics")
// return an error
} else {
log.Println("Error, the handler was neither accessed using a GET or a POST request!")
}
}
func main() {
// parse some command line flags
var port string
flag.StringVar(&port, "p", "8080", "port used to host the service")
flag.Parse()
log.Println("[ ] Done loading the flags")
// setup a new router and define routes
r := mux.NewRouter()
r.HandleFunc("/metrics", metricsHandler).Methods("GET", "POST")
// start the http server
log.Printf("Starting the http server on port %s", port)
log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), r))
}
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