proxyd: Log sanitized RPC requests (#2470)

.changeset/blue-olives-add.md

+---
+'@eth-optimism/proxyd': patch
+---
+
+proxyd: Log ssanitized RPC requests

go/proxyd/server.go

@@ -27,6 +27,7 @@ const (
 	MaxBatchRPCCalls        = 100
 	cacheStatusHdr          = "X-Proxyd-Cache-Status"
 	defaultServerTimeout    = time.Second * 10
+	maxLogLength            = 1000
 )
 
 type Server struct {
@@ -237,6 +238,12 @@ func (s *Server) handleSingleRPC(ctx context.Context, req *RPCReq) (*RPCRes, boo
 		return NewRPCErrorRes(req.ID, ErrMethodNotWhitelisted), false
 	}
 
+	log.Info("RPC request",
+		"method", req.Method,
+		"params", truncate(string(req.Params)),
+		"id", truncate(string(req.ID)),
+	)
+
 	var backendRes *RPCRes
 	backendRes, err := s.cache.GetRPC(ctx, req)
 	if err != nil {
@@ -457,3 +464,11 @@ func (n *NoopRPCCache) GetRPC(context.Context, *RPCReq) (*RPCRes, error) {
 func (n *NoopRPCCache) PutRPC(context.Context, *RPCReq, *RPCRes) error {
 	return nil
 }
+
+func truncate(str string) string {
+	if len(str) > maxLogLength {
+		return str[:maxLogLength] + "..."
+	} else {
+		return str
+	}
+}