refactor hasher

api/hasher/hasher.go

@@ -8,6 +8,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"sort"
+
+	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
 // SortArrayAndComputeHash sorts a string array and
@@ -50,3 +52,141 @@ func Encode(hex string) (string, error) {
 func Hash(data string) string {
 	return fmt.Sprintf("%x", sha256.Sum256([]byte(data)))
 }
+
+// HashRNode returns the hash value of input RNode
+func HashRNode(node *yaml.RNode) (string, error) {
+	// get node kind
+	kindNode, err := node.Pipe(yaml.FieldMatcher{Name: "kind"})
+	if err != nil {
+		return "", err
+	}
+	kind := kindNode.YNode().Value
+
+	// calculate hash for different kinds
+	switch kind {
+	case "ConfigMap":
+		return configMapHash(node)
+	case "Secret":
+		return secretHash(node)
+	default:
+		return defaultHash(node)
+	}
+}
+
+// configMapHash returns a hash of the ConfigMap.
+// The Data, Kind, and Name are taken into account.
+func configMapHash(node *yaml.RNode) (string, error) {
+	encoded, err := encodeConfigMap(node)
+	if err != nil {
+		return "", err
+	}
+	h, err := Encode(Hash(encoded))
+	if err != nil {
+		return "", err
+	}
+	return h, nil
+}
+
+// SecretHash returns a hash of the Secret.
+// The Data, Kind, Name, and Type are taken into account.
+func secretHash(node *yaml.RNode) (string, error) {
+	encoded, err := encodeSecret(node)
+	if err != nil {
+		return "", err
+	}
+	h, err := Encode(Hash(encoded))
+	if err != nil {
+		return "", err
+	}
+	return h, nil
+}
+
+// unstructuredHash creates a hash for an arbitrary type.
+// All fields of the object are taken into account when generating the hash.
+// This is a fallback for when a specalised hash for the type is unavailable.
+func defaultHash(node *yaml.RNode) (string, error) {
+	encoded, err := json.Marshal(node.YNode())
+	if err != nil {
+		return "", err
+	}
+	h, err := Encode(Hash(string(encoded)))
+	if err != nil {
+		return "", err
+	}
+	return h, nil
+}
+
+func getNodeValues(node *yaml.RNode, paths []string) (map[string]interface{}, error) {
+	values := make(map[string]interface{})
+	for _, p := range paths {
+		vn, err := node.Pipe(yaml.Lookup(p))
+		if err != nil {
+			return map[string]interface{}{}, err
+		}
+		if vn == nil {
+			values[p] = ""
+			continue
+		}
+		if vn.YNode().Kind != yaml.ScalarNode {
+			vs, err := vn.MarshalJSON()
+			if err != nil {
+				return map[string]interface{}{}, err
+			}
+			// data, binaryData and stringData are all maps
+			var v map[string]interface{}
+			json.Unmarshal(vs, &v)
+			values[p] = v
+		} else {
+			values[p] = vn.YNode().Value
+		}
+	}
+	return values, nil
+}
+
+// encodeConfigMap encodes a ConfigMap.
+// Data, Kind, and Name are taken into account.
+// BinaryData is included if it's not empty to avoid useless key in output.
+func encodeConfigMap(node *yaml.RNode) (string, error) {
+	// get fields
+	paths := []string{"metadata/name", "data", "binaryData"}
+	values, err := getNodeValues(node, paths)
+	if err != nil {
+		return "", err
+	}
+	m := map[string]interface{}{"kind": "ConfigMap", "name": values["metadata/name"],
+		"data": values["data"]}
+	if _, ok := values["binaryData"].(map[string]interface{}); ok {
+		m["binaryData"] = values["binaryData"]
+	}
+
+	// json.Marshal sorts the keys in a stable order in the encoding
+	data, err := json.Marshal(m)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}
+
+// encodeSecret encodes a Secret.
+// Data, Kind, Name, and Type are taken into account.
+// StringData is included if it's not empty to avoid useless key in output.
+func encodeSecret(node *yaml.RNode) (string, error) {
+	// get fields
+	paths := []string{"type", "metadata/name", "data", "stringData"}
+	values, err := getNodeValues(node, paths)
+	if err != nil {
+		return "", err
+	}
+	m := map[string]interface{}{"kind": "Secret", "type": values["type"],
+		"name": values["metadata/name"], "data": values["data"]}
+	if _, ok := values["stringData"].(map[string]interface{}); ok {
+		m["stringData"] = values["stringData"]
+	}
+
+	// json.Marshal sorts the keys in a stable order in the encoding
+	data, err := json.Marshal(m)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}