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// Copyright 2015 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 api provides clients for the HTTP APIs.
package api
import (
"bytes"
"context"
"errors"
"net"
"net/http"
"net/url"
"path"
"strings"
"time"
)
// DefaultRoundTripper is used if no RoundTripper is set in Config.
var DefaultRoundTripper http.RoundTripper = &http.Transport{
Proxy: http.ProxyFromEnvironment,
DialContext: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).DialContext,
TLSHandshakeTimeout: 10 * time.Second,
}
// Config defines configuration parameters for a new client.
type Config struct {
// The address of the Prometheus to connect to.
Address string
// Client is used by the Client to drive HTTP requests. If not provided,
// a new one based on the provided RoundTripper (or DefaultRoundTripper) will be used.
Client *http.Client
// RoundTripper is used by the Client to drive HTTP requests. If not
// provided, DefaultRoundTripper will be used.
RoundTripper http.RoundTripper
}
func (cfg *Config) roundTripper() http.RoundTripper {
if cfg.RoundTripper == nil {
return DefaultRoundTripper
}
return cfg.RoundTripper
}
func (cfg *Config) client() http.Client {
if cfg.Client == nil {
return http.Client{
Transport: cfg.roundTripper(),
}
}
return *cfg.Client
}
func (cfg *Config) validate() error {
if cfg.Client != nil && cfg.RoundTripper != nil {
return errors.New("api.Config.RoundTripper and api.Config.Client are mutually exclusive")
}
return nil
}
// Client is the interface for an API client.
type Client interface {
URL(ep string, args map[string]string) *url.URL
Do(context.Context, *http.Request) (*http.Response, []byte, error)
}
type CloseIdler interface {
CloseIdleConnections()
}
// NewClient returns a new Client.
//
// It is safe to use the returned Client from multiple goroutines.
func NewClient(cfg Config) (Client, error) {
u, err := url.Parse(cfg.Address)
if err != nil {
return nil, err
}
u.Path = strings.TrimRight(u.Path, "/")
if err := cfg.validate(); err != nil {
return nil, err
}
return &httpClient{
endpoint: u,
client: cfg.client(),
}, nil
}
type httpClient struct {
endpoint *url.URL
client http.Client
}
func (c *httpClient) URL(ep string, args map[string]string) *url.URL {
p := path.Join(c.endpoint.Path, ep)
for arg, val := range args {
arg = ":" + arg
p = strings.ReplaceAll(p, arg, val)
}
u := *c.endpoint
u.Path = p
return &u
}
func (c *httpClient) CloseIdleConnections() {
c.client.CloseIdleConnections()
}
func (c *httpClient) Do(ctx context.Context, req *http.Request) (*http.Response, []byte, error) {
if ctx != nil {
req = req.WithContext(ctx)
}
resp, err := c.client.Do(req)
if err != nil {
return nil, nil, err
}
var body []byte
done := make(chan error, 1)
go func() {
var buf bytes.Buffer
_, err := buf.ReadFrom(resp.Body)
body = buf.Bytes()
done <- err
}()
select {
case <-ctx.Done():
resp.Body.Close()
<-done
return resp, nil, ctx.Err()
case err = <-done:
resp.Body.Close()
return resp, body, err
}
}
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