Create omitted function

Signed-off-by: Bruno Almeida <bruno.almeida@nokia.com>

pkg/engine/funcs.go

@@ -55,6 +55,8 @@ func funcMap() template.FuncMap {
 		"fromJson":      fromJSON,
 		"fromJsonArray": fromJSONArray,
 
+		"omitted": omitted,
+
 		// This is a placeholder for the "include" function, which is
 		// late-bound to a template. By declaring it here, we preserve the
 		// integrity of the linter.
@@ -174,3 +176,10 @@ func fromJSONArray(str string) []interface{} {
 	}
 	return a
 }
+
+func omitted(a, b interface{}) interface{} {
+	if b == nil {
+		return a
+	}
+	return b
+}

pkg/engine/funcs_test.go

@@ -94,6 +94,14 @@ func TestFuncs(t *testing.T) {
 		tpl:    `{{ fromYamlArray . }}`,
 		expect: `[error unmarshaling JSON: while decoding JSON: json: cannot unmarshal object into Go value of type []interface {}]`,
 		vars:   `hello: world`,
+	}, {
+		tpl:    `{{ .hello | omitted 'yes' }}`,
+		expect: `false`,
+		vars:   map[string]bool{"hello": false},
+	}, {
+		tpl:    `{{ .value | omitted 'yes' }}`,
+		expect: `yes`,
+		vars:   map[string]bool{"hello": false},
 	}, {
 		// This should never result in a network lookup. Regression for #7955
 		tpl:    `{{ lookup "v1" "Namespace" "" "unlikelynamespace99999999" }}`,