add ability to update yaml path while preserving comments

2 files changed, 118 insertions, 0 deletions

diff --git a/pkg/utils/yaml_utils/yaml_utils.go b/pkg/utils/yaml_utils/yaml_utils.go
new file mode 100644
index 000000000..9ed7ae875
--- /dev/null
+++ b/pkg/utils/yaml_utils/yaml_utils.go
@@ -0,0 +1,54 @@
+package yaml_utils
+
+import (
+	"fmt"
+
+	"gopkg.in/yaml.v3"
+)
+
+// takes a yaml document in bytes, a path to a key, and a value to set. The value must be a scalar.
+func UpdateYaml(yamlBytes []byte, path []string, value string) ([]byte, error) {
+	// Parse the YAML file.
+	var node yaml.Node
+	err := yaml.Unmarshal(yamlBytes, &node)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse YAML: %w", err)
+	}
+
+	body := node.Content[0]
+
+	updateYamlNode(body, path, value)
+
+	// Convert the updated YAML node back to YAML bytes.
+	updatedYAMLBytes, err := yaml.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to convert YAML node to bytes: %w", err)
+	}
+
+	return updatedYAMLBytes, nil
+}
+
+// Recursive function to update the YAML node.
+func updateYamlNode(node *yaml.Node, path []string, value string) {
+	if len(path) == 0 {
+		node.Value = value
+		return
+	}
+
+	key := path[0]
+	for i := 0; i < len(node.Content)-1; i += 2 {
+		if node.Content[i].Value == key {
+			updateYamlNode(node.Content[i+1], path[1:], value)
+			return
+		}
+	}
+
+	// if the key doesn't exist, we'll add it
+	node.Content = append(node.Content, &yaml.Node{
+		Kind:  yaml.ScalarNode,
+		Value: key,
+	}, &yaml.Node{
+		Kind:  yaml.ScalarNode,
+		Value: value,
+	})
+}
diff --git a/pkg/utils/yaml_utils/yaml_utils_test.go b/pkg/utils/yaml_utils/yaml_utils_test.go
new file mode 100644
index 000000000..4bdfeb432
--- /dev/null
+++ b/pkg/utils/yaml_utils/yaml_utils_test.go
@@ -0,0 +1,64 @@
+package yaml_utils
+
+import "testing"
+
+func TestUpdateYaml(t *testing.T) {
+	tests := []struct {
+		name        string
+		in          string
+		path        []string
+		value       string
+		expectedOut string
+		expectedErr string
+	}{
+		{
+			name:        "update value",
+			in:          "foo: bar\n",
+			path:        []string{"foo"},
+			value:       "baz",
+			expectedOut: "foo: baz\n",
+			expectedErr: "",
+		},
+		{
+			name:        "add new key and value",
+			in:          "foo: bar\n",
+			path:        []string{"foo2"},
+			value:       "baz",
+			expectedOut: "foo: bar\nfoo2: baz\n",
+			expectedErr: "",
+		},
+		{
+			name:        "preserve inline comment",
+			in:          "foo: bar # my comment\n",
+			path:        []string{"foo2"},
+			value:       "baz",
+			expectedOut: "foo: bar # my comment\nfoo2: baz\n",
+			expectedErr: "",
+		},
+		{
+			name:  "nested update",
+			in:    "foo:\n  bar: baz\n",
+			path:  []string{"foo", "bar"},
+			value: "qux",
+			// indentation is not preserved. See https://github.com/go-yaml/yaml/issues/899
+			expectedOut: "foo:\n    bar: qux\n",
+			expectedErr: "",
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			out, err := UpdateYaml([]byte(test.in), test.path, test.value)
+			if test.expectedErr != "" {
+				if err == nil {
+					t.Errorf("expected error %q but got none", test.expectedErr)
+				}
+			} else if err != nil {
+				t.Errorf("unexpected error: %v", err)
+			} else if string(out) != test.expectedOut {
+				t.Errorf("expected %q but got %q", test.expectedOut, string(out))
+			}
+		})
+	}
+}