Switch to s3 multipart uploads for backups

api/api.go

@@ -185,7 +185,7 @@ func (r *Response) Error() error {
 	var bag RequestErrorBag
 	_ = r.Bind(&bag)
 
-	e := new(RequestError)
+	e := &RequestError{}
 	if len(bag.Errors) > 0 {
 		e = &bag.Errors[0]
 	}

api/backup_endpoints.go

@@ -3,8 +3,35 @@ package api
 import (
 	"fmt"
 	"github.com/pkg/errors"
+	"strconv"
 )
 
+type BackupRemoteUploadResponse struct {
+	CompleteMultipartUpload string
+	AbortMultipartUpload    string
+	Parts                   []string
+	PartSize                int64
+}
+
+func (r *Request) GetBackupRemoteUploadURLs(backup string, size int64) (*BackupRemoteUploadResponse, error) {
+	resp, err := r.Get(fmt.Sprintf("/backups/%s", backup), Q{"size": strconv.FormatInt(size, 10)})
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+	defer resp.Body.Close()
+
+	if resp.HasError() {
+		return nil, resp.Error()
+	}
+
+	var res BackupRemoteUploadResponse
+	if err := resp.Bind(&res); err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	return &res, nil
+}
+
 type BackupRequest struct {
 	Checksum     string `json:"checksum"`
 	ChecksumType string `json:"checksum_type"`