added opensearch serverless support

Signed-off-by: vasyaxparfenov <[email protected]>

provider/awsv4.go

@@ -0,0 +1,39 @@
+package provider
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"io"
+	"net/http"
+)
+
+var emptyStringSHA256 = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+
+type awsV4SignerWrapper struct {
+	internal http.RoundTripper
+}
+
+func (client *awsV4SignerWrapper) RoundTrip(request *http.Request) (*http.Response, error) {
+	var hash string
+	if request.Body == nil {
+		hash = emptyStringSHA256
+	} else {
+		payload, error := io.ReadAll(request.Body)
+		request.Body = io.NopCloser(bytes.NewReader(payload))
+		if error != nil {
+			return nil, error
+		}
+		hasher := sha256.New()
+		hasher.Write(payload)
+		hashBytes := hasher.Sum(nil)
+		hash = hex.EncodeToString(hashBytes)
+	}
+	request.Header.Set("X-Amz-Content-Sha256", hash)
+
+	return client.internal.RoundTrip(request)
+}
+
+func Wrap(internal http.RoundTripper) http.RoundTripper {
+	return &awsV4SignerWrapper{internal: internal}
+}

provider/provider.go

@@ -38,6 +38,8 @@ const (
 )
 
 var awsUrlRegexp = regexp.MustCompile(`([a-z0-9-]+).es.amazonaws.com$`)
+var awsOpensearchServerlessUrlRegexp = regexp.MustCompile(`([a-z0-9-]+).aoss.amazonaws.com$`)
+var minimalOpensearchServerlessVersion = "2.0.0"
 
 type ProviderConf struct {
 	rawUrl                  string
@@ -305,6 +307,25 @@ func getClient(conf *ProviderConf) (*elastic7.Client, error) {
 			return nil, err
 		}
 		opts = append(opts, elastic7.SetHttpClient(client), elastic7.SetSniff(false))
+	} else if m := awsOpensearchServerlessUrlRegexp.FindStringSubmatch(conf.parsedUrl.Hostname()); (m != nil || (conf.awsSig4Service == "aoss" && conf.awsRegion != "")) && conf.signAWSRequests {
+		var region string
+		if m != nil {
+			region = m[1]
+		} else {
+			region = conf.awsRegion
+		}
+		log.Printf("[INFO] Using AWS: %+v", region)
+		conf.awsSig4Service = "aoss"
+		client, err := awsHttpClient(region, conf, map[string]string{})
+		if err != nil {
+			return nil, err
+		}
+		client.Transport = Wrap(client.Transport)
+		opts = append(opts, elastic7.SetHttpClient(client), elastic7.SetSniff(false))
+		conf.flavor = OpenSearch
+		if conf.osVersion == "" {
+			conf.osVersion = minimalOpensearchServerlessVersion
+		}
 	} else if awsRegion := conf.awsRegion; conf.awsRegion != "" && conf.signAWSRequests {
 		log.Printf("[INFO] Using AWS: %+v", awsRegion)
 		client, err := awsHttpClient(awsRegion, conf, map[string]string{})