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// Copyright 2022 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package roundtripper
import (
"bytes"
"context"
"crypto/sha256"
"encoding/hex"
"io"
"log/slog"
"net/http"
"time"
"github.com/aws/aws-sdk-go-v2/aws"
v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/credentials/stscreds"
"github.com/aws/aws-sdk-go-v2/service/sts"
)
const (
service = "es"
)
type AWSSigningTransport struct {
t http.RoundTripper
creds aws.CredentialsProvider
region string
log *slog.Logger
}
func NewAWSSigningTransport(transport http.RoundTripper, region string, roleArn string, log *slog.Logger) (*AWSSigningTransport, error) {
cfg, err := config.LoadDefaultConfig(context.Background(), config.WithRegion(region))
if err != nil {
log.Error("failed to load aws default config", "err", err)
return nil, err
}
if roleArn != "" {
cfg.Credentials = stscreds.NewAssumeRoleProvider(sts.NewFromConfig(cfg), roleArn)
}
creds := aws.NewCredentialsCache(cfg.Credentials)
// Run a single fetch credentials operation to ensure that the credentials
// are valid before returning the transport.
_, err = cfg.Credentials.Retrieve(context.Background())
if err != nil {
log.Error("failed to retrive aws credentials", "err", err)
return nil, err
}
return &AWSSigningTransport{
t: transport,
region: region,
creds: creds,
log: log,
}, err
}
func (a *AWSSigningTransport) RoundTrip(req *http.Request) (*http.Response, error) {
signer := v4.NewSigner()
payloadHash, newReader, err := hashPayload(req.Body)
if err != nil {
a.log.Error("failed to hash request body", "err", err)
return nil, err
}
req.Body = newReader
creds, err := a.creds.Retrieve(context.Background())
if err != nil {
a.log.Error("failed to retrieve aws credentials", "err", err)
return nil, err
}
err = signer.SignHTTP(context.Background(), creds, req, payloadHash, service, a.region, time.Now())
if err != nil {
a.log.Error("failed to sign request body", "err", err)
return nil, err
}
return a.t.RoundTrip(req)
}
func hashPayload(r io.ReadCloser) (string, io.ReadCloser, error) {
var newReader io.ReadCloser
payload := []byte("")
if r != nil {
defer r.Close()
payload, err := io.ReadAll(r)
if err != nil {
return "", newReader, err
}
newReader = io.NopCloser(bytes.NewReader(payload))
}
hash := sha256.Sum256(payload)
payloadHash := hex.EncodeToString(hash[:])
return payloadHash, newReader, nil
}
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