fix: argument list to long error for large dags

Signed-off-by: Anay Sharma <anay20sharma11@gmail.com>

Author: AnaySharmaCode

backend/src/v2/cmd/driver/main.go

@@ -29,6 +29,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"strings"
 
 	"github.com/golang/glog"
 	"github.com/kubeflow/pipelines/api/v2alpha1/go/pipelinespec"
@@ -146,6 +147,18 @@ func drive() (err error) {
 		return err
 	}
 
+	// Support reading component spec from a file if value starts with @
+	// This bypasses exec() argument size limits for large workflows
+	if strings.HasPrefix(*componentSpecJson, "@") {
+		filePath := (*componentSpecJson)[1:] // Remove the "@" prefix
+		data, err := os.ReadFile(filePath)
+		if err != nil {
+			return fmt.Errorf("failed to read component spec from file %s: %w", filePath, err)
+		}
+		*componentSpecJson = string(data)
+		glog.Infof("Read component spec from file: %s (%d bytes)", filePath, len(data))
+	}
+
 	proxy.InitializeConfig(*httpProxy, *httpsProxy, *noProxy)
 	glog.Infof("input ComponentSpec:%s\n", prettyPrint(*componentSpecJson))
 	componentSpec := &pipelinespec.ComponentSpec{}