monorepo

Co-authored-by: Malte Poll <mp@edgeless.systems>
Co-authored-by: katexochen <katexochen@users.noreply.github.com>
Co-authored-by: Daniel Weiße <dw@edgeless.systems>
Co-authored-by: Thomas Tendyck <tt@edgeless.systems>
Co-authored-by: Benedict Schlueter <bs@edgeless.systems>
Co-authored-by: leongross <leon.gross@rub.de>
Co-authored-by: Moritz Eckert <m1gh7ym0@gmail.com>

coordinator/kubernetes/k8sapi/resources/marshal.go

@@ -0,0 +1,124 @@
+package resources
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+
+	"gopkg.in/yaml.v3"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	"k8s.io/client-go/kubernetes/scheme"
+)
+
+// Marshaler is used by all k8s resources that can be marshaled to YAML.
+type Marshaler interface {
+	Marshal() ([]byte, error)
+}
+
+// MarshalK8SResources marshals every field of a struct into a k8s resource YAML.
+func MarshalK8SResources(resources interface{}) ([]byte, error) {
+	serializer := json.NewYAMLSerializer(json.DefaultMetaFactory, nil, nil)
+	var buf bytes.Buffer
+
+	// reflect over struct containing fields that are k8s resources
+	value := reflect.ValueOf(resources)
+	if value.Kind() != reflect.Ptr && value.Kind() != reflect.Interface {
+		return nil, errors.New("marshal on non-pointer called")
+	}
+	elem := value.Elem()
+	if elem.Kind() == reflect.Struct {
+		// iterate over all struct fields
+		for i := 0; i < elem.NumField(); i++ {
+			field := elem.Field(i)
+			var inter interface{}
+			// check if value can be converted to interface
+			if field.CanInterface() {
+				inter = field.Addr().Interface()
+			} else {
+				continue
+			}
+			// convert field interface to runtime.Object
+			obj, ok := inter.(runtime.Object)
+			if !ok {
+				continue
+			}
+
+			if i > 0 {
+				// separate YAML documents
+				buf.Write([]byte("---\n"))
+			}
+			// serialize k8s resource
+			if err := serializer.Encode(obj, &buf); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+// UnmarshalK8SResources takes YAML and converts it into a k8s resources struct.
+func UnmarshalK8SResources(data []byte, into interface{}) error {
+	// reflect over struct containing fields that are k8s resources
+	value := reflect.ValueOf(into).Elem()
+	if value.Kind() != reflect.Struct {
+		return errors.New("can only reflect over struct")
+	}
+
+	decoder := serializer.NewCodecFactory(scheme.Scheme).UniversalDecoder()
+	documents, err := splitYAML(data)
+	if err != nil {
+		return fmt.Errorf("unable to split deployment YAML into multiple documents: %w", err)
+	}
+	if len(documents) != value.NumField() {
+		return fmt.Errorf("expected %v YAML documents, got %v", value.NumField(), len(documents))
+	}
+
+	for i := 0; i < value.NumField(); i++ {
+		field := value.Field(i)
+		var inter interface{}
+		// check if value can be converted to interface
+		if !field.CanInterface() {
+			return fmt.Errorf("cannot use struct field %v as interface", i)
+		}
+		inter = field.Addr().Interface()
+		// convert field interface to runtime.Object
+		obj, ok := inter.(runtime.Object)
+		if !ok {
+			return fmt.Errorf("cannot convert struct field %v as k8s runtime object", i)
+		}
+
+		// decode YAML document into struct field
+		if err := runtime.DecodeInto(decoder, documents[i], obj); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// splitYAML splits a YAML multidoc into a slice of multiple YAML docs.
+func splitYAML(resources []byte) ([][]byte, error) {
+	dec := yaml.NewDecoder(bytes.NewReader(resources))
+	var res [][]byte
+	for {
+		var value interface{}
+		err := dec.Decode(&value)
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		valueBytes, err := yaml.Marshal(value)
+		if err != nil {
+			return nil, err
+		}
+		res = append(res, valueBytes)
+	}
+	return res, nil
+}