Allow custom headers in validator client HTTP requests (#15884)

* Allow custom headers in validator client HTTP requests

* changelog <3

* improve flag description

* Bastin's review

* James' review

* add godoc for NodeConnectionOption

validator/helpers/node_connection.go

@@ -10,16 +10,37 @@ import (
 type NodeConnection interface {
 	GetGrpcClientConn() *grpc.ClientConn
 	GetBeaconApiUrl() string
+	GetBeaconApiHeaders() map[string][]string
+	setBeaconApiHeaders(map[string][]string)
 	GetBeaconApiTimeout() time.Duration
+	setBeaconApiTimeout(time.Duration)
 	dummy()
 }
 
 type nodeConnection struct {
 	grpcClientConn   *grpc.ClientConn
 	beaconApiUrl     string
+	beaconApiHeaders map[string][]string
 	beaconApiTimeout time.Duration
 }
 
+// NodeConnectionOption is a functional option for configuring the node connection.
+type NodeConnectionOption func(nc NodeConnection)
+
+// WithBeaconApiHeaders sets the HTTP headers that should be sent to the server along with each request.
+func WithBeaconApiHeaders(headers map[string][]string) NodeConnectionOption {
+	return func(nc NodeConnection) {
+		nc.setBeaconApiHeaders(headers)
+	}
+}
+
+// WithBeaconApiTimeout sets the HTTP request timeout.
+func WithBeaconApiTimeout(timeout time.Duration) NodeConnectionOption {
+	return func(nc NodeConnection) {
+		nc.setBeaconApiTimeout(timeout)
+	}
+}
+
 func (c *nodeConnection) GetGrpcClientConn() *grpc.ClientConn {
 	return c.grpcClientConn
 }
@@ -28,16 +49,30 @@ func (c *nodeConnection) GetBeaconApiUrl() string {
 	return c.beaconApiUrl
 }
 
+func (c *nodeConnection) GetBeaconApiHeaders() map[string][]string {
+	return c.beaconApiHeaders
+}
+
+func (c *nodeConnection) setBeaconApiHeaders(headers map[string][]string) {
+	c.beaconApiHeaders = headers
+}
+
 func (c *nodeConnection) GetBeaconApiTimeout() time.Duration {
 	return c.beaconApiTimeout
 }
 
+func (c *nodeConnection) setBeaconApiTimeout(timeout time.Duration) {
+	c.beaconApiTimeout = timeout
+}
+
 func (*nodeConnection) dummy() {}
 
-func NewNodeConnection(grpcConn *grpc.ClientConn, beaconApiUrl string, beaconApiTimeout time.Duration) NodeConnection {
+func NewNodeConnection(grpcConn *grpc.ClientConn, beaconApiUrl string, opts ...NodeConnectionOption) NodeConnection {
 	conn := &nodeConnection{}
 	conn.grpcClientConn = grpcConn
 	conn.beaconApiUrl = beaconApiUrl
-	conn.beaconApiTimeout = beaconApiTimeout
+	for _, opt := range opts {
+		opt(conn)
+	}
 	return conn
 }