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http.go
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http.go
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// Copyright 2016 CoreOS, Inc.
//
// 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 resource
import (
"errors"
"io"
"net"
"net/http"
"time"
"github.com/coreos/ignition/config/types"
"github.com/coreos/ignition/internal/log"
"github.com/coreos/ignition/internal/version"
"golang.org/x/net/context"
"golang.org/x/net/context/ctxhttp"
)
const (
initialBackoff = 100 * time.Millisecond
maxBackoff = 5 * time.Second
defaultHttpResponseHeaderTimeout = 10
defaultHttpTotalTimeout = 0
)
var (
ErrTimeout = errors.New("unable to fetch resource in time")
)
// HttpClient is a simple wrapper around the Go HTTP client that standardizes
// the process and logging of fetching payloads.
type HttpClient struct {
client *http.Client
logger *log.Logger
timeout time.Duration
}
// NewHttpClient creates a new client with the given logger and timeouts.
func NewHttpClient(logger *log.Logger, timeouts types.Timeouts) HttpClient {
responseHeader := defaultHttpResponseHeaderTimeout
total := defaultHttpTotalTimeout
if timeouts.HTTPResponseHeaders != nil {
responseHeader = *timeouts.HTTPResponseHeaders
}
if timeouts.HTTPTotal != nil {
total = *timeouts.HTTPTotal
}
return HttpClient{
client: &http.Client{
Transport: &http.Transport{
ResponseHeaderTimeout: time.Duration(responseHeader) * time.Second,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
Resolver: &net.Resolver{
PreferGo: true,
},
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
},
},
logger: logger,
timeout: time.Duration(total) * time.Second,
}
}
// getReaderWithHeader performs an HTTP GET on the provided URL with the provided request header
// and returns the response body Reader, HTTP status code, and error (if any). By
// default, User-Agent is added to the header but this can be overridden.
func (c HttpClient) getReaderWithHeader(url string, header http.Header) (io.ReadCloser, int, error) {
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return nil, 0, err
}
req.Header.Set("User-Agent", "Ignition/"+version.Raw)
for key, values := range header {
req.Header.Del(key)
for _, value := range values {
req.Header.Add(key, value)
}
}
ctx := context.Background()
if c.timeout != 0 {
ctx, _ = context.WithTimeout(ctx, c.timeout)
}
duration := initialBackoff
for attempt := 1; ; attempt++ {
c.logger.Debug("GET %s: attempt #%d", url, attempt)
resp, err := ctxhttp.Do(ctx, c.client, req)
if err == nil {
c.logger.Debug("GET result: %s", http.StatusText(resp.StatusCode))
if resp.StatusCode < 500 {
return resp.Body, resp.StatusCode, nil
}
resp.Body.Close()
} else {
c.logger.Debug("GET error: %v", err)
}
duration = duration * 2
if duration > maxBackoff {
duration = maxBackoff
}
// Wait before next attempt or exit if we timeout while waiting
select {
case <-time.After(duration):
case <-ctx.Done():
return nil, 0, ErrTimeout
}
}
}