feat: print resources with a matching label selector

cmd/command.go

@@ -227,7 +227,7 @@ func Command() *cobra.Command { //nolint:funlen
 		"output",
 		"o",
 		"",
-		"output format (json,name,path,references,table,yaml)")
+		"output format (json,name,path,references,selector,table,yaml)")
 
 	var state struct {
 		allMatchers matcher.Matcher

printer/printer.go

@@ -46,6 +46,9 @@ func ByName(name string) (func(io.Writer, []resources.Resource) error, error) {
 	case "references":
 		return References, nil
 
+	case "selector":
+		return Selector, nil
+
 	case "table":
 		return Table, nil
 

printer/selector.go

@@ -0,0 +1,47 @@
+// Copyright Josh Komoroske. All rights reserved.
+// Use of this source code is governed by the MIT license,
+// a copy of which can be found in the LICENSE.txt file.
+// SPDX-License-Identifier: MIT
+
+package printer
+
+import (
+	"fmt"
+	"io"
+	"maps"
+	"slices"
+	"strings"
+
+	"github.com/rodaine/table"
+
+	"github.com/joshdk/krf/resources"
+)
+
+// Selector prints each given resources.Resource with the resource name and a
+// matching label selector.
+func Selector(w io.Writer, items []resources.Resource) error {
+	tbl := table.New("Name", "Selector")
+	tbl.WithPrintHeaders(false)
+	tbl.WithWriter(w)
+
+	for _, item := range items {
+		var (
+			labels    = item.GetLabels()
+			selectors []string
+		)
+
+		// Sort all labels by key name.
+		for _, key := range slices.Sorted(maps.Keys(labels)) {
+			selectors = append(selectors, fmt.Sprintf("%s=%s", key, labels[key]))
+		}
+
+		tbl.AddRow(
+			fmt.Sprintf("%s/%s", item.GetKind(), item.GetName()),
+			strings.Join(selectors, ","),
+		)
+	}
+
+	tbl.Print()
+
+	return nil
+}