feat: read targets from stdin (#35)

Signed-off-by: Jian Zeng <[email protected]>

cmd/client/main.go

@@ -68,11 +68,16 @@ func (o *Options) Run(ctx context.Context, args []string) error {
 
 	var targets []target
 	if len(o.targetsFile) > 0 {
-		fin, err := os.Open(o.targetsFile)
-		if err != nil {
-			return err
+		var fin *os.File
+		if o.targetsFile == "-" {
+			fin = os.Stdin
+		} else {
+			fin, err = os.Open(o.targetsFile)
+			if err != nil {
+				return err
+			}
+			defer fin.Close()
 		}
-		defer fin.Close()
 		targets, err = parseTargetsFile(fin, ns)
 		if err != nil {
 			return err

cmd/client/template.go

@@ -34,6 +34,9 @@ func example() string {
 
   # Create the agent in the kube-public namespace, and forward local port 5000 to "1.2.3.4:5000"
   {{.Name}} --server.namespace kube-public ip/1.2.3.4 5000
+
+  # Forward traffic to multiple targets
+  echo 'ip/1.2.3.4 5000\nsvc/my-service 8080:80\n-n kube-system deploy/coredns 5353:53@udp' | {{.Name}} -f -
 `
 	tpl, err := template.New("example").Parse(text)
 	if err != nil {