157 lines
3.7 KiB
Go
157 lines
3.7 KiB
Go
// Copyright 2015 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 api provides clients for the HTTP APIs.
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package api
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import (
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"context"
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"io/ioutil"
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"net"
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"net/http"
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"net/url"
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"path"
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"strings"
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"time"
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)
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type Warnings []string
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// DefaultRoundTripper is used if no RoundTripper is set in Config.
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var DefaultRoundTripper http.RoundTripper = &http.Transport{
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Proxy: http.ProxyFromEnvironment,
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DialContext: (&net.Dialer{
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Timeout: 30 * time.Second,
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KeepAlive: 30 * time.Second,
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}).DialContext,
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TLSHandshakeTimeout: 10 * time.Second,
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}
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// Config defines configuration parameters for a new client.
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type Config struct {
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// The address of the Prometheus to connect to.
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Address string
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// RoundTripper is used by the Client to drive HTTP requests. If not
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// provided, DefaultRoundTripper will be used.
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RoundTripper http.RoundTripper
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}
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func (cfg *Config) roundTripper() http.RoundTripper {
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if cfg.RoundTripper == nil {
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return DefaultRoundTripper
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}
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return cfg.RoundTripper
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}
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// Client is the interface for an API client.
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type Client interface {
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URL(ep string, args map[string]string) *url.URL
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Do(context.Context, *http.Request) (*http.Response, []byte, Warnings, error)
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}
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// DoGetFallback will attempt to do the request as-is, and on a 405 it will fallback to a GET request.
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func DoGetFallback(c Client, ctx context.Context, u *url.URL, args url.Values) (*http.Response, []byte, Warnings, error) {
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req, err := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(args.Encode()))
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if err != nil {
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return nil, nil, nil, err
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}
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req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
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resp, body, warnings, err := c.Do(ctx, req)
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if resp != nil && resp.StatusCode == http.StatusMethodNotAllowed {
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u.RawQuery = args.Encode()
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req, err = http.NewRequest(http.MethodGet, u.String(), nil)
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if err != nil {
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return nil, nil, warnings, err
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}
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} else {
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if err != nil {
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return resp, body, warnings, err
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}
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return resp, body, warnings, nil
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}
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return c.Do(ctx, req)
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}
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// NewClient returns a new Client.
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//
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// It is safe to use the returned Client from multiple goroutines.
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func NewClient(cfg Config) (Client, error) {
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u, err := url.Parse(cfg.Address)
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if err != nil {
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return nil, err
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}
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u.Path = strings.TrimRight(u.Path, "/")
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return &httpClient{
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endpoint: u,
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client: http.Client{Transport: cfg.roundTripper()},
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}, nil
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}
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type httpClient struct {
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endpoint *url.URL
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client http.Client
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}
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func (c *httpClient) URL(ep string, args map[string]string) *url.URL {
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p := path.Join(c.endpoint.Path, ep)
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for arg, val := range args {
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arg = ":" + arg
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p = strings.Replace(p, arg, val, -1)
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}
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u := *c.endpoint
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u.Path = p
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return &u
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}
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func (c *httpClient) Do(ctx context.Context, req *http.Request) (*http.Response, []byte, Warnings, error) {
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if ctx != nil {
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req = req.WithContext(ctx)
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}
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resp, err := c.client.Do(req)
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defer func() {
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if resp != nil {
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resp.Body.Close()
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}
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}()
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if err != nil {
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return nil, nil, nil, err
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}
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var body []byte
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done := make(chan struct{})
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go func() {
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body, err = ioutil.ReadAll(resp.Body)
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close(done)
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}()
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select {
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case <-ctx.Done():
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<-done
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err = resp.Body.Close()
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if err == nil {
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err = ctx.Err()
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}
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case <-done:
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}
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return resp, body, nil, err
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}
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