Alerting: Support tls config for webhook receiver (#93513)

Adds the ability to configure tls settings on the webhook receiver (e.g. to skip server certificate validation)

pkg/services/notifications/webhook.go

@@ -7,10 +7,10 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"net"
 	"net/http"
 	"net/url"
-	"time"
+
+	alertingReceivers "github.com/grafana/alerting/receivers"
 
 	"github.com/grafana/grafana/pkg/util"
 )
@@ -23,6 +23,7 @@ type Webhook struct {
 	HttpMethod  string
 	HttpHeader  map[string]string
 	ContentType string
+	TLSConfig   *tls.Config
 
 	// Validation is a function that will validate the response body and statusCode of the webhook. Any returned error will cause the webhook request to be considered failed.
 	// This can be useful when a webhook service communicates failures in creative ways, such as using the response body instead of the status code.
@@ -34,21 +35,6 @@ type WebhookClient interface {
 	Do(req *http.Request) (*http.Response, error)
 }
 
-var netTransport = &http.Transport{
-	TLSClientConfig: &tls.Config{
-		Renegotiation: tls.RenegotiateFreelyAsClient,
-	},
-	Proxy: http.ProxyFromEnvironment,
-	Dial: (&net.Dialer{
-		Timeout: 30 * time.Second,
-	}).Dial,
-	TLSHandshakeTimeout: 5 * time.Second,
-}
-var netClient WebhookClient = &http.Client{
-	Timeout:   time.Second * 30,
-	Transport: netTransport,
-}
-
 func (ns *NotificationService) sendWebRequestSync(ctx context.Context, webhook *Webhook) error {
 	if webhook.HttpMethod == "" {
 		webhook.HttpMethod = http.MethodPost
@@ -85,7 +71,7 @@ func (ns *NotificationService) sendWebRequestSync(ctx context.Context, webhook *
 		request.Header.Set(k, v)
 	}
 
-	resp, err := netClient.Do(request)
+	resp, err := alertingReceivers.NewTLSClient(webhook.TLSConfig).Do(request)
 	if err != nil {
 		return redactURL(err)
 	}