charm-cinder-backup-swift-proxy installed python-swiftclient wrong parsing on swift endpoint url

[Yanos Angelopoulos]

In our case, we wanted to use a Swift endpoint on Ceph (ceph-radosgw) for our volume backups.

We used the charm "cinder-backup-swift-proxy".
Among other packages, it also installs the apt package "python3-swiftclient".

In the charm options we used the field:
endpoint-url: "https://radosgw-endpoint:80/swift/"

The fact that the endpoint URL contains a path after the port (swift/) resulted in the following error:

2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall [-] Fixed interval looping call 'cinder.backup.manager.BackupManager._setup_backup_driver' failed: swiftclient.exceptions.ClientException: Capabilities GET failed: https://radosgw-endpoint:80/info 404 Not Found [first 60 chars of response] b'<?xml version="1.0" encoding="UTF-8"?><Error><Code>NoSuchBucket'
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall Traceback (most recent call last):
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall File "/usr/lib/python3/dist-packages/oslo_service/loopingcall.py", line 150, in _run_loop
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall result = func(*self.args, **self.kw)
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall File "/usr/lib/python3/dist-packages/cinder/backup/manager.py", line 163, in _setup_backup_driver
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall backup_service.check_for_setup_error()
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall File "/usr/lib/python3/dist-packages/cinder/backup/drivers/swift.py", line 394, in check_for_setup_error
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall conn.get_capabilities()
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall File "/usr/lib/python3/dist-packages/swiftclient/client.py", line 1928, in get_capabilities
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall return get_capabilities((parsed, self.http_conn[1]))
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall File "/usr/lib/python3/dist-packages/swiftclient/client.py", line 1565, in get_capabilities
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall resp, 'Capabilities GET failed', body)
2020-05-08 18:59:43.374 39951 ERROR oslo.service.loopingcall swiftclient.exceptions.ClientException: Capabilities GET failed: https://radosgw-endpoint:80/info 404 Not Found [first 60 chars of response] b'<?xml version="1.0" encoding="UTF-8"?><Error><Code>NoSuchBucket'

So the URL given was: "https://radosgw-endpoint:80/swift/"
but the URL used was: "https://radosgw-endpoint:80/info/" instead of "https://radosgw-endpoint:80/swift/info/"

This happens because of the python3-swiftclient code, in file "/usr/lib/python3/dist-packages/swiftclient/client.py" in line 1921:

    def get_capabilities(self, url=None):
        url = url or self.url
        if not url:
            url, _ = self.get_auth()
        parsed = urlparse(urljoin(url, '/info'))
        if not self.http_conn:
            self.http_conn = self.http_connection(url)
        return get_capabilities((parsed, self.http_conn[1]))

The line "parsed = urlparse(urljoin(url, '/info'))" removes the existing path ("/swift") from the url.

This issue seems to be fixed in the master branch of "python-swiftclient":
https://opendev.org/openstack/python-swiftclient/src/branch/master/swiftclient/client.py

I think we need an updated version on python3-swiftclient for the apt package.