Fallback to default S3 URL on empty media upload URL in settings.

frontend/src/views/settings/media.vue

@@ -95,8 +95,7 @@
             label-position="on-border"
             :message="$t('settings.media.s3.urlHelp')" expanded>
             <b-input v-model="data['upload.s3.url']"
-              name="upload.s3.url"
-              :disabled="!data['upload.s3.bucket']"
+              name="upload.s3.url" :disabled="!data['upload.s3.bucket']" required
               placeholder="https://s3.region.amazonaws.com" :maxlength="200" />
           </b-field>
         </div>

internal/media/providers/s3/s3.go

@@ -1,7 +1,7 @@
 package s3
 
 import (
-	"errors"
+	"fmt"
 	"io"
 	"strings"
 	"time"
@@ -36,7 +36,7 @@ func NewS3Store(opt Opt) (media.Store, error) {
 		err error
 	)
 	if opt.URL == "" {
-		return nil, errors.New("Invalid AWS URL in settings.")
+		opt.URL = fmt.Sprintf("https://s3.%s.amazonaws.com", opt.Region)
 	}
 	opt.URL = strings.TrimRight(opt.URL, "/")