Signing of Elastic requests (https://github.com/elastic/go-elasticsearch) according to AWS v4 Signing process

elastic_sample.go

cfg, err := external.LoadDefaultAWSConfig()
if err != nil {
  panic(err)
}
esCfg := elasticsearch.Config{
  Transport: &awssigner.V4Signer{
    RoundTripper: http.DefaultTransport,
    Credentials:  cfg.Credentials,
    Region:       cfg.Region,
  },
}
es, err := elasticsearch.NewClient(esCfg)
if err != nil {
  panic(err)
}

res, err := es.Search(
  es.Search.WithBody(strings.NewReader(`{"query": {"match_all": {}}}`)),
)
if err != nil {
  panic(err)
}

b, err := ioutil.ReadAll(res.Body)
if err != nil {
  panic(err)
}
log.Printf("response: %s", b)

v4signer.go

package awssigner

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"net/http"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
)

// V4Signer is a http.RoundTripper implementation to sign requests according to
// https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html. Many libraries allow customizing the behavior
// of HTTP requests, providing a transport. A V4Signer transport can be instantiated as follow:
//
// 	cfg, err := external.LoadDefaultAWSConfig()
//	if err != nil {
//		...
//	}
//	transport := &V4Signer{
//		RoundTripper: http.DefaultTransport,
//		Credentials:  cfg.Credentials,
//		Region:       cfg.Region,
//	}
type V4Signer struct {
	RoundTripper http.RoundTripper
	Credentials  aws.CredentialsProvider
	Region       string
}

func (s *V4Signer) RoundTrip(req *http.Request) (*http.Response, error) {
	signer := v4.NewSigner(s.Credentials)
	switch req.Body {
	case nil:
		_, err := signer.Sign(req, nil, "es", s.Region, time.Now())
		if err != nil {
			return nil, fmt.Errorf("error signing request: %w", err)
		}
	default:
		b, err := ioutil.ReadAll(req.Body)
		if err != nil {
			return nil, err
		}
		_, err = signer.Sign(req, bytes.NewReader(b), "es", s.Region, time.Now())
		if err != nil {
			return nil, fmt.Errorf("error signing request: %w", err)
		}
		req.Body = ioutil.NopCloser(bytes.NewReader(b))
	}
	return s.RoundTripper.RoundTrip(req)
}

Thanks a lot, works perfectly.

This isn't working with aws-sdk-go-v2 v0.22.0 (Sign was deprecated and now has a ctx parameter). I left an updated example in https://github.com/jriquelme/awsgosigv4.