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client.go
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client.go
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// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package auth
import (
"context"
"log"
"math"
"net"
"net/http"
"net/url"
"runtime"
"strconv"
"time"
"github.com/hashicorp/go-retryablehttp"
)
type httpClientParams struct {
instanceMetadataService bool
retryWaitMin time.Duration
retryWaitMax time.Duration
retryMaxCount int
useProxy bool
}
func defaultHttpClientParams() httpClientParams {
return httpClientParams{
instanceMetadataService: false,
retryWaitMin: 1 * time.Second,
retryWaitMax: 30 * time.Second,
retryMaxCount: 8,
useProxy: true,
}
}
// httpClient returns a shimmed retryablehttp Client, with custom backoff and
// retry settings which can be customized per instance as needed.
func httpClient(params httpClientParams) *http.Client {
r := retryablehttp.NewClient()
r.Logger = log.Default()
r.Backoff = func(min, max time.Duration, attemptNum int, resp *http.Response) time.Duration {
// note: min and max contain the values of r.RetryWaitMin and r.RetryWaitMax
if resp != nil {
if params.instanceMetadataService {
// IMDS uses inappropriate 410 status to indicate a rebooting-like state, retry after 70 seconds
// See https://learn.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/how-to-use-vm-token#retry-guidance
if resp.StatusCode == http.StatusGone {
return 70 * time.Second
}
}
// Always look for Retry-After header, regardless of HTTP status
if s, ok := resp.Header["Retry-After"]; ok {
if sleep, err := strconv.ParseInt(s[0], 10, 64); err == nil {
return time.Second * time.Duration(sleep)
}
}
}
// Exponential backoff when Retry-After header not provided, e.g. IMDS
mult := math.Pow(2, float64(attemptNum)) * float64(min)
sleep := time.Duration(mult)
if float64(sleep) != mult || sleep > max {
sleep = max
}
return sleep
}
var proxyFunc func(*http.Request) (*url.URL, error)
if params.useProxy {
proxyFunc = http.ProxyFromEnvironment
}
r.RetryWaitMin = params.retryWaitMin
r.RetryWaitMax = params.retryWaitMax
r.HTTPClient = &http.Client{
Transport: &http.Transport{
Proxy: proxyFunc,
DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
d := &net.Dialer{Resolver: &net.Resolver{}}
return d.DialContext(ctx, network, addr)
},
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
ForceAttemptHTTP2: true,
MaxIdleConnsPerHost: runtime.GOMAXPROCS(0) + 1,
},
}
return r.StandardClient()
}