prometheus/util/httputil/client.go

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// Copyright 2013 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 httputil
import (
"crypto/tls"
"crypto/x509"
"fmt"
"io/ioutil"
"net/http"
"strings"
"time"
"github.com/mwitkow/go-conntrack"
"github.com/prometheus/prometheus/config"
)
// NewClient returns a http.Client using the specified http.RoundTripper.
func newClient(rt http.RoundTripper) *http.Client {
return &http.Client{Transport: rt}
}
// NewClientFromConfig returns a new HTTP client configured for the
// given config.HTTPClientConfig. The name is used as go-conntrack metric label.
func NewClientFromConfig(cfg config.HTTPClientConfig, name string) (*http.Client, error) {
tlsConfig, err := NewTLSConfig(cfg.TLSConfig)
if err != nil {
return nil, err
}
// The only timeout we care about is the configured scrape timeout.
// It is applied on request. So we leave out any timings here.
var rt http.RoundTripper = &http.Transport{
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Proxy: http.ProxyURL(cfg.ProxyURL.URL),
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MaxIdleConns: 20000,
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DisableKeepAlives: false,
TLSClientConfig: tlsConfig,
DisableCompression: true,
// 5 minutes is typically above the maximum sane scrape interval. So we can
// use keepalive for all configurations.
IdleConnTimeout: 5 * time.Minute,
DialContext: conntrack.NewDialContextFunc(
conntrack.DialWithTracing(),
conntrack.DialWithName(name),
),
}
// If a bearer token is provided, create a round tripper that will set the
// Authorization header correctly on each request.
bearerToken := string(cfg.BearerToken)
if len(bearerToken) == 0 && len(cfg.BearerTokenFile) > 0 {
b, err := ioutil.ReadFile(cfg.BearerTokenFile)
if err != nil {
return nil, fmt.Errorf("unable to read bearer token file %s: %s", cfg.BearerTokenFile, err)
}
bearerToken = strings.TrimSpace(string(b))
}
if len(bearerToken) > 0 {
rt = NewBearerAuthRoundTripper(bearerToken, rt)
}
if cfg.BasicAuth != nil {
rt = NewBasicAuthRoundTripper(cfg.BasicAuth.Username, string(cfg.BasicAuth.Password), rt)
}
// Return a new client with the configured round tripper.
return newClient(rt), nil
}
type bearerAuthRoundTripper struct {
bearerToken string
rt http.RoundTripper
}
// NewBearerAuthRoundTripper adds the provided bearer token to a request unless the authorization
// header has already been set.
func NewBearerAuthRoundTripper(bearer string, rt http.RoundTripper) http.RoundTripper {
return &bearerAuthRoundTripper{bearer, rt}
}
func (rt *bearerAuthRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
if len(req.Header.Get("Authorization")) == 0 {
req = cloneRequest(req)
req.Header.Set("Authorization", "Bearer "+rt.bearerToken)
}
return rt.rt.RoundTrip(req)
}
type basicAuthRoundTripper struct {
username string
password string
rt http.RoundTripper
}
// NewBasicAuthRoundTripper will apply a BASIC auth authorization header to a request unless it has
// already been set.
func NewBasicAuthRoundTripper(username, password string, rt http.RoundTripper) http.RoundTripper {
return &basicAuthRoundTripper{username, password, rt}
}
func (rt *basicAuthRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
if len(req.Header.Get("Authorization")) != 0 {
return rt.rt.RoundTrip(req)
}
req = cloneRequest(req)
req.SetBasicAuth(rt.username, rt.password)
return rt.rt.RoundTrip(req)
}
// cloneRequest returns a clone of the provided *http.Request.
// The clone is a shallow copy of the struct and its Header map.
func cloneRequest(r *http.Request) *http.Request {
// Shallow copy of the struct.
r2 := new(http.Request)
*r2 = *r
// Deep copy of the Header.
r2.Header = make(http.Header)
for k, s := range r.Header {
r2.Header[k] = s
}
return r2
}
// NewTLSConfig creates a new tls.Config from the given config.TLSConfig.
func NewTLSConfig(cfg config.TLSConfig) (*tls.Config, error) {
tlsConfig := &tls.Config{InsecureSkipVerify: cfg.InsecureSkipVerify}
// If a CA cert is provided then let's read it in so we can validate the
// scrape target's certificate properly.
if len(cfg.CAFile) > 0 {
caCertPool := x509.NewCertPool()
// Load CA cert.
caCert, err := ioutil.ReadFile(cfg.CAFile)
if err != nil {
return nil, fmt.Errorf("unable to use specified CA cert %s: %s", cfg.CAFile, err)
}
caCertPool.AppendCertsFromPEM(caCert)
tlsConfig.RootCAs = caCertPool
}
if len(cfg.ServerName) > 0 {
tlsConfig.ServerName = cfg.ServerName
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}
// If a client cert & key is provided then configure TLS config accordingly.
if len(cfg.CertFile) > 0 && len(cfg.KeyFile) > 0 {
cert, err := tls.LoadX509KeyPair(cfg.CertFile, cfg.KeyFile)
if err != nil {
return nil, fmt.Errorf("unable to use specified client cert (%s) & key (%s): %s", cfg.CertFile, cfg.KeyFile, err)
}
tlsConfig.Certificates = []tls.Certificate{cert}
}
tlsConfig.BuildNameToCertificate()
return tlsConfig, nil
}