Topology command: open svg graph in the user’s preferred application

cmd/topology.go

@@ -2,8 +2,11 @@ package cmd
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"os"
+	"os/exec"
+	"strings"
 
 	"github.com/goccy/go-graphviz"
 	"github.com/spf13/cobra"
@@ -22,13 +25,13 @@ var (
 func topologyCommand() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "topology",
-		Short: "Read kuadrant topology",
-		Long:  "Read kuadrant topology",
+		Short: "Export and visualize kuadrant topology",
+		Long:  "Export and visualize kuadrant topology",
 		RunE:  runTopology,
 	}
 
 	cmd.Flags().StringVarP(&topologyNS, "namespace", "n", "kuadrant-system", "Topology's namespace")
-	cmd.Flags().StringVarP(&topologyOutputFile, "output", "o", "(required)", "Output file")
+	cmd.Flags().StringVarP(&topologyOutputFile, "output", "o", "", "Output file")
 	err := cmd.MarkFlagRequired("output")
 	if err != nil {
 		panic(err)
@@ -37,6 +40,9 @@ func topologyCommand() *cobra.Command {
 }
 
 func runTopology(cmd *cobra.Command, args []string) error {
+	if !strings.HasSuffix(topologyOutputFile, ".svg") {
+		return errors.New("output file must have .svg extension")
+	}
 	ctx := cmd.Context()
 	configuration, err := config.GetConfig()
 	if err != nil {
@@ -108,5 +114,16 @@ func runTopology(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
+	openCmd := exec.Command("open", topologyOutputFile)
+	// pipe the commands output to the applications
+	// standard output
+	openCmd.Stdout = os.Stdout
+
+	// Run still runs the command and waits for completion
+	// but the output is instantly piped to Stdout
+	if err := openCmd.Run(); err != nil {
+		return err
+	}
+
 	return nil
 }