139 lines
4.1 KiB
Go
139 lines
4.1 KiB
Go
// Copyright 2021 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package remote
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import (
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"bytes"
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"net/textproto"
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"sync"
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"time"
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"github.com/aws/aws-sdk-go/aws"
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"github.com/aws/aws-sdk-go/aws/credentials"
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"github.com/aws/aws-sdk-go/aws/credentials/stscreds"
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"github.com/aws/aws-sdk-go/aws/session"
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signer "github.com/aws/aws-sdk-go/aws/signer/v4"
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"github.com/prometheus/prometheus/config"
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)
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var sigv4HeaderDenylist = []string{
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"uber-trace-id",
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}
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type sigV4RoundTripper struct {
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region string
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next http.RoundTripper
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pool sync.Pool
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signer *signer.Signer
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}
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// newSigV4RoundTripper returns a new http.RoundTripper that will sign requests
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// using Amazon's Signature Verification V4 signing procedure. The request will
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// then be handed off to the next RoundTripper provided by next. If next is nil,
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// http.DefaultTransport will be used.
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//
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// Credentials for signing are retrieved using the the default AWS credential
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// chain. If credentials cannot be found, an error will be returned.
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func newSigV4RoundTripper(cfg *config.SigV4Config, next http.RoundTripper) (http.RoundTripper, error) {
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if next == nil {
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next = http.DefaultTransport
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}
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creds := credentials.NewStaticCredentials(cfg.AccessKey, string(cfg.SecretKey), "")
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if cfg.AccessKey == "" && cfg.SecretKey == "" {
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creds = nil
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}
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sess, err := session.NewSessionWithOptions(session.Options{
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Config: aws.Config{
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Region: aws.String(cfg.Region),
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Credentials: creds,
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},
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Profile: cfg.Profile,
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})
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if err != nil {
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return nil, fmt.Errorf("could not create new AWS session: %w", err)
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}
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if _, err := sess.Config.Credentials.Get(); err != nil {
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return nil, fmt.Errorf("could not get SigV4 credentials: %w", err)
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}
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if aws.StringValue(sess.Config.Region) == "" {
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return nil, fmt.Errorf("region not configured in sigv4 or in default credentials chain")
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}
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signerCreds := sess.Config.Credentials
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if cfg.RoleARN != "" {
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signerCreds = stscreds.NewCredentials(sess, cfg.RoleARN)
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}
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rt := &sigV4RoundTripper{
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region: cfg.Region,
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next: next,
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signer: signer.NewSigner(signerCreds),
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}
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rt.pool.New = rt.newBuf
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return rt, nil
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}
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func (rt *sigV4RoundTripper) newBuf() interface{} {
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return bytes.NewBuffer(make([]byte, 0, 1024))
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}
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func (rt *sigV4RoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
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// rt.signer.Sign needs a seekable body, so we replace the body with a
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// buffered reader filled with the contents of original body.
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buf := rt.pool.Get().(*bytes.Buffer)
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defer func() {
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buf.Reset()
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rt.pool.Put(buf)
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}()
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if _, err := io.Copy(buf, req.Body); err != nil {
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return nil, err
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}
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// Close the original body since we don't need it anymore.
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_ = req.Body.Close()
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// Ensure our seeker is back at the start of the buffer once we return.
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var seeker io.ReadSeeker = bytes.NewReader(buf.Bytes())
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defer func() {
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_, _ = seeker.Seek(0, io.SeekStart)
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}()
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req.Body = ioutil.NopCloser(seeker)
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// Clone the request and trim out headers that we don't want to sign.
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signReq := req.Clone(req.Context())
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for _, header := range sigv4HeaderDenylist {
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signReq.Header.Del(header)
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}
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headers, err := rt.signer.Sign(signReq, seeker, "aps", rt.region, time.Now().UTC())
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if err != nil {
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return nil, fmt.Errorf("failed to sign request: %w", err)
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}
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// Copy over signed headers. Authorization header is not returned by
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// rt.signer.Sign and needs to be copied separately.
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for k, v := range headers {
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req.Header[textproto.CanonicalMIMEHeaderKey(k)] = v
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}
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req.Header.Set("Authorization", signReq.Header.Get("Authorization"))
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return rt.next.RoundTrip(req)
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}
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