otc: use default transport (#2363)

providers/dns/otc/otc.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"net"
 	"net/http"
 	"time"
 
@@ -55,28 +54,25 @@ type Config struct {
 
 // NewDefaultConfig returns a default configuration for the DNSProvider.
 func NewDefaultConfig() *Config {
+	tr := &http.Transport{}
+
+	defaultTransport, ok := http.DefaultTransport.(*http.Transport)
+	if ok {
+		tr = defaultTransport.Clone()
+	}
+
+	// Workaround for keep alive bug in otc api
+	tr.DisableKeepAlives = true
+
 	return &Config{
 		TTL:                env.GetOrDefaultInt(EnvTTL, minTTL),
 		PropagationTimeout: env.GetOrDefaultSecond(EnvPropagationTimeout, dns01.DefaultPropagationTimeout),
 		PollingInterval:    env.GetOrDefaultSecond(EnvPollingInterval, dns01.DefaultPollingInterval),
 		IdentityEndpoint:   env.GetOrDefaultString(EnvIdentityEndpoint, defaultIdentityEndpoint),
 		SequenceInterval:   env.GetOrDefaultSecond(EnvSequenceInterval, dns01.DefaultPropagationTimeout),
 		HTTPClient: &http.Client{
-			Timeout: env.GetOrDefaultSecond(EnvHTTPTimeout, 10*time.Second),
-			Transport: &http.Transport{
-				Proxy: http.ProxyFromEnvironment,
-				DialContext: (&net.Dialer{
-					Timeout:   30 * time.Second,
-					KeepAlive: 30 * time.Second,
-				}).DialContext,
-				MaxIdleConns:          100,
-				IdleConnTimeout:       90 * time.Second,
-				TLSHandshakeTimeout:   10 * time.Second,
-				ExpectContinueTimeout: 1 * time.Second,
-
-				// Workaround for keep alive bug in otc api
-				DisableKeepAlives: true,
-			},
+			Timeout:   env.GetOrDefaultSecond(EnvHTTPTimeout, 10*time.Second),
+			Transport: tr,
 		},
 	}
 }