go-server-json-output.go

package main

import (
    "fmt"
    "log"

    "flag"

    "os"
    "time"

    "net/http"

    "encoding/json"
)

var (
    port int
)

func rootHandler(w http.ResponseWriter, r *http.Request) {
    // http://golang.org/pkg/encoding/json/#Encoder
    encoder := json.NewEncoder(w)

    respData := struct {
        LocalTime time.Time
        Hostname string
    } {}

    respData.LocalTime = time.Now()
    respData.Hostname, _ = os.Hostname()

    if err := encoder.Encode(&respData); err != nil {
        http.Error(w, fmt.Sprintf("Cannot encode response data: %v", err), 500)
    }
}

func init() {
    flag.IntVar(&port, "port", 8080, "HTTP Server Port")
    flag.Parse()
}

func main() {
    httpAddr := fmt.Sprintf(":%v", port)

    log.Printf("Listening to %v", httpAddr)

    http.HandleFunc("/", rootHandler)
    log.Fatal(http.ListenAndServe(httpAddr, nil))
}