Using a stream is a no-go due to a bug in libcloud: https://issues.apache.org/jira/browse/LIBCLOUD-935?focusedCommentId=16152982&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-16152982 Instead, write the uploaded file to a named tempfile and pass that to the uploader.