Comment 15 for bug 1978444

Reviewed: https://review.opendev.org/c/openstack/nova/+/866087
Committed: https://opendev.org/openstack/nova/commit/3cb1e35b5e3a3f8949bb0fd31fb8a246c5346703
Submitter: "Zuul (22348)"
Branch: stable/victoria

commit 3cb1e35b5e3a3f8949bb0fd31fb8a246c5346703
Author: Takashi Kajinami <email address hidden>
Date: Mon Jun 13 14:48:24 2022 +0900

    Retry attachment delete API call for 504 Gateway Timeout

    When cinder-api runs behind a load balancer(eg haproxy), the load
    balancer can return 504 Gateway Timeout when cinder-api does not
    respond within timeout. This change ensures nova retries deleting
    a volume attachment in that case.

    Also this change makes nova ignore 404 in the API call. This is
    required because cinder might continue deleting the attachment even if
    the load balancer returns 504. This also helps us in the situation
    where the volume attachment was accidentally removed by users.

    Conflicts:
        nova/tests/unit/volume/test_cinder.py
        nova/volume/cinder.py

    NOTE(melwitt): The conflicts are due to the following changes not in
    Victoria:

      * I23bb9e539d08f5c6202909054c2dd49b6c7a7a0e
        (Remove six.text_type (1/2))

      * I779bd1446dc1f070fa5100ccccda7881fa508d79
        (Remove six.text_type (2/2))

    Closes-Bug: #1978444
    Change-Id: I593011d9f4c43cdae7a3d53b556c6e2a2b939989
    (cherry picked from commit 8f4b740ca5292556f8e953a30f2a11ed4fbc2945)
    (cherry picked from commit b94ffb1123b1a6cf0a8675e0d6f1072e9625f570)
    (cherry picked from commit 14f9b7627e8a48f546e2f1c79d4336e1e4923501)
    (cherry picked from commit 9b1c078112f11eafbd8e174efbd0e0f9d2c951ee)