[probes.http] Allow specifying proxy connect headers (#763)

probes/http/http.go

@@ -123,6 +123,10 @@ func (p *Probe) getTransport() (*http.Transport, error) {
 			return nil, fmt.Errorf("error parsing proxy URL (%s): %v", p.c.GetProxyUrl(), err)
 		}
 		transport.Proxy = http.ProxyURL(url)
+
+		for k, v := range p.c.GetProxyConnectHeader() {
+			transport.ProxyConnectHeader.Add(k, v)
+		}
 	}
 
 	if p.c.GetDisableCertValidation() || p.c.GetTlsConfig() != nil {

probes/http/proto/config.proto

@@ -74,7 +74,7 @@ message ProbeConf {
   // }   
   repeated Header headers = 8;
   map<string, string> header = 20;
-
+  
   // Request body. This field works similar to the curl's data flag. If there
   // are multiple "body" fields, we combine their values with a '&' in between.
   //
@@ -118,6 +118,11 @@ message ProbeConf {
   // Proxy URL, e.g. http://myproxy:3128
   optional string proxy_url = 16;
 
+  // HTTP proxy connect headers. These headers are passed on to the CONNECT
+  // requests to the HTTP proxies. Note that CONNECT method is used to fetch
+  // HTTPS URLs via HTTP proxies.
+  map<string, string> proxy_connect_header = 23;
+
   // User agent. Default user agent is Go's default user agent.
   optional string user_agent = 19;
 

probes/http/proto/config_proto_gen.cue

@@ -130,6 +130,13 @@ import (
 	// Proxy URL, e.g. http://myproxy:3128
 	proxyUrl?: string @protobuf(16,string,name=proxy_url)
 
+	// HTTP proxy connect headers. These headers are passed on to the CONNECT
+	// requests to the HTTP proxies. Note that CONNECT method is used to fetch
+	// HTTPS URLs via HTTP proxies.
+	proxyConnectHeader?: {
+		[string]: string
+	} @protobuf(23,map[string]string,proxy_connect_header)
+
 	// User agent. Default user agent is Go's default user agent.
 	userAgent?: string @protobuf(19,string,name=user_agent)