add internal droplets package to parse a policy

internal/droplets/droplets.go

@@ -0,0 +1,58 @@
+package droplets
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/digitalocean/godo"
+	"sigs.k8s.io/yaml"
+)
+
+func ReadDropletBackupPolicy(stdin io.Reader, path string) (*godo.DropletBackupPolicyRequest, error) {
+	var policy io.Reader
+	if path == "-" && stdin != nil {
+		policy = stdin
+	} else {
+		specFile, err := os.Open(path) // guardrails-disable-line
+		if err != nil {
+			if os.IsNotExist(err) {
+				return nil, fmt.Errorf("opening droplet backup policy: %s does not exist", path)
+			}
+			return nil, fmt.Errorf("opening droplet backup policy: %w", err)
+		}
+		defer specFile.Close()
+		policy = specFile
+	}
+
+	byt, err := io.ReadAll(policy)
+	if err != nil {
+		return nil, fmt.Errorf("reading droplet backup policy: %w", err)
+	}
+
+	s, err := ParseDropletBackupPolicy(byt)
+	if err != nil {
+		return nil, fmt.Errorf("parsing droplet backup policy: %w", err)
+	}
+
+	return s, nil
+}
+
+func ParseDropletBackupPolicy(spec []byte) (*godo.DropletBackupPolicyRequest, error) {
+	jsonSpec, err := yaml.YAMLToJSON(spec)
+	if err != nil {
+		return nil, err
+	}
+
+	dec := json.NewDecoder(bytes.NewReader(jsonSpec))
+	dec.DisallowUnknownFields()
+
+	var policy godo.DropletBackupPolicyRequest
+	if err := dec.Decode(&policy); err != nil {
+		return nil, err
+	}
+
+	return &policy, nil
+}

internal/droplets/droplets_test.go

@@ -0,0 +1 @@
+package droplets