From ddd65eda580c59f0895f30f8193f9f9ae17c2640 Mon Sep 17 00:00:00 2001
From: Marcin Owsiany <mowsiany@D2iQ.com>
Date: Tue, 3 Mar 2020 08:35:11 +0100
Subject: [PATCH] KEP-25: Implementation of toYaml function. (#1375)

Signed-off-by: Marcin Owsiany <mowsiany@D2iQ.com>
---
 pkg/engine/renderer/engine.go      | 2 ++
 pkg/engine/renderer/engine_test.go | 8 ++++++++
 pkg/engine/renderer/functions.go   | 9 +++++++++
 3 files changed, 19 insertions(+)
 create mode 100644 pkg/engine/renderer/functions.go

diff --git a/pkg/engine/renderer/engine.go b/pkg/engine/renderer/engine.go
index 6eccb158e..2d2802276 100644
--- a/pkg/engine/renderer/engine.go
+++ b/pkg/engine/renderer/engine.go
@@ -34,6 +34,8 @@ type Engine struct {
 func New() *Engine {
 	f := sprig.TxtFuncMap()
 
+	f["toYaml"] = ToYaml
+
 	// Prevent environment access inside the running KUDO Controller
 	funcs := []string{"env", "expandenv", "base", "dir", "clean", "ext", "isAbs"}
 
diff --git a/pkg/engine/renderer/engine_test.go b/pkg/engine/renderer/engine_test.go
index b43bb299a..7f41a5796 100644
--- a/pkg/engine/renderer/engine_test.go
+++ b/pkg/engine/renderer/engine_test.go
@@ -22,6 +22,14 @@ func TestRender(t *testing.T) {
 			},
 			expected: "Name: Bob User"},
 		{name: "function", template: "Name: {{ .Params.Name | upper }}", params: map[string]interface{}{"Name": "hello"}, expected: "Name: HELLO"},
+		{
+			name:     "toYaml",
+			template: "{{ toYaml .Params.Dict | trim | indent 2 }}",
+			params: map[string]interface{}{
+				"Dict": map[string]string{"Foo": "Bar", "Baz": "Quux"},
+			},
+			expected: "  Baz: Quux\n  Foo: Bar",
+		},
 	}
 
 	engine := New()
diff --git a/pkg/engine/renderer/functions.go b/pkg/engine/renderer/functions.go
new file mode 100644
index 000000000..44c09f19c
--- /dev/null
+++ b/pkg/engine/renderer/functions.go
@@ -0,0 +1,9 @@
+package renderer
+
+import "gopkg.in/yaml.v2"
+
+// ToYaml takes any value, and returns its YAML representation as a string.
+func ToYaml(v interface{}) (string, error) {
+	out, err := yaml.Marshal(v)
+	return string(out), err
+}