customization.go

// +build ignore

package main

import (
	"bytes"
	"io/ioutil"
	"log"
	"net/http"
	"strings"

	"github.com/elastic/go-elasticsearch"
)

// This example demonstrates how to provide a custom transport implementation to the client

// LoggingTransport implements the `http.RoundTripper` interface, so it can be passed
// to the client as a custom HTTP transport implementation.
//
type LoggingTransport struct{}

// RoundTrip executes a request, returning a response, and prints information about the flow.
//
func (t *LoggingTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	// Print information about the request
	log.Println(strings.Repeat("=", 80))
	log.Printf("> %s %s\n", req.Method, req.URL.String())
	log.Println(strings.Repeat("-", 80))

	res, err := http.DefaultTransport.RoundTrip(req)
	if err == nil {
		// Print information about the response
		log.Printf("< [%s] %s", res.Status, res.Header.Get("Content-Type"))
		body, err := ioutil.ReadAll(res.Body)
		if err == nil {
			// Print the body
			defer func() { res.Body = ioutil.NopCloser(bytes.NewReader(body)) }()
			defer func() { res.Body.Close() }()
			for _, line := range strings.Split(string(body), "\n") {
				if line != "" {
					log.Printf("< %s\n", line)
				}
			}
		}
		log.Println(strings.Repeat("=", 80))
	} else {
		// Print the error
		log.Println("ERROR:", err)
	}

	return res, err
}

func main() {
	log.SetFlags(0)

	es, _ := elasticsearch.NewClient(
		elasticsearch.Config{Transport: &LoggingTransport{}},
	)

	res, err := es.Info()
	if err != nil {
		log.Fatalf("ERROR: %s\n", err)
	}
	defer res.Body.Close()

	log.Printf("Response: %s", res.Status())
}