Added `toYamlPretty` template function

Signed-off-by: Fred Heinecke <fred.heinecke@goteleport.com>

go.mod

@@ -45,7 +45,7 @@ require (
 	k8s.io/klog/v2 v2.100.1
 	k8s.io/kubectl v0.28.2
 	oras.land/oras-go v1.2.4
-	sigs.k8s.io/yaml v1.3.0
+	sigs.k8s.io/yaml v1.4.0
 )
 
 require (

go.sum

@@ -555,3 +555,5 @@ sigs.k8s.io/structured-merge-diff/v4 v4.2.3 h1:PRbqxJClWWYMNV1dhaG4NsibJbArud9kF
 sigs.k8s.io/structured-merge-diff/v4 v4.2.3/go.mod h1:qjx8mGObPmV2aSZepjQjbmb2ihdVs8cGKBraizNC69E=
 sigs.k8s.io/yaml v1.3.0 h1:a2VclLzOGrwOHDiV8EfBGhvjHvP46CtW5j6POvhYGGo=
 sigs.k8s.io/yaml v1.3.0/go.mod h1:GeOyir5tyXNByN85N/dRIT9es5UQNerPYEKK56eTBm8=
+sigs.k8s.io/yaml v1.4.0 h1:Mk1wCc2gy/F0THH0TAp1QYyJNzRm2KCLy3o5ASXVI5E=
+sigs.k8s.io/yaml v1.4.0/go.mod h1:Ejl7/uTz7PSA4eKMyQCUTnhZYNmLIl+5c2lQPGR2BPY=

pkg/engine/funcs.go

@@ -25,6 +25,7 @@ import (
 	"github.com/BurntSushi/toml"
 	"github.com/Masterminds/sprig/v3"
 	"sigs.k8s.io/yaml"
+	goYaml "sigs.k8s.io/yaml/goyaml.v3"
 )
 
 // funcMap returns a mapping of all of the functions that Engine has.
@@ -49,6 +50,7 @@ func funcMap() template.FuncMap {
 	extra := template.FuncMap{
 		"toToml":        toTOML,
 		"toYaml":        toYAML,
+		"toYamlPretty":  toYAMLPretty,
 		"fromYaml":      fromYAML,
 		"fromYamlArray": fromYAMLArray,
 		"toJson":        toJSON,
@@ -88,6 +90,19 @@ func toYAML(v interface{}) string {
 	return strings.TrimSuffix(string(data), "\n")
 }
 
+func toYAMLPretty(v interface{}) string {
+	var data bytes.Buffer
+	encoder := goYaml.NewEncoder(&data)
+	encoder.SetIndent(2)
+	err := encoder.Encode(v)
+
+	if err != nil {
+		// Swallow errors inside of a template.
+		return ""
+	}
+	return strings.TrimSuffix(data.String(), "\n")
+}
+
 // fromYAML converts a YAML document into a map[string]interface{}.
 //
 // This is not a general-purpose YAML parser, and will not parse all valid

pkg/engine/funcs_test.go

@@ -33,6 +33,10 @@ func TestFuncs(t *testing.T) {
 		tpl:    `{{ toYaml . }}`,
 		expect: `foo: bar`,
 		vars:   map[string]interface{}{"foo": "bar"},
+	}, {
+		tpl:    `{{ toYamlPretty . }}`,
+		expect: "baz:\n  - 1\n  - 2\n  - 3",
+		vars:   map[string]interface{}{"baz": []int{1, 2, 3}},
 	}, {
 		tpl:    `{{ toToml . }}`,
 		expect: "foo = \"bar\"\n",