Comment 5 for bug 1924917

Reviewed: https://review.opendev.org/c/openstack/tacker/+/815416
Committed: https://opendev.org/openstack/tacker/commit/d40de6c71ecf9d5d31d31ddc94b4ae8ad40f2ca8
Submitter: "Zuul (22348)"
Branch: master

commit d40de6c71ecf9d5d31d31ddc94b4ae8ad40f2ca8
Author: Hiromu Asahina <email address hidden>
Date: Fri Oct 29 23:02:03 2021 +0900

    Fix LCM failure

    In current implementation, if the tacker servers go down during LCM
    operation, the operation state will be fixed to `PROCESSING` even after
    servers restart. Once this problem happens, users cannot change the
    operation state with APIs, which means users have to change the state by
    updating DB directly.

    This patch fixes this problem by adding a `/vnf_lcm_op_occs/{id}/cancel`
    endpoint according to ETSI NFV SOL003 [1]. Users can change the state of
    LCM operations in `PROCESSING` to `FAILED_TEMP` with this API.

    Note that currently the cancel API support only a transition from
    PROCESSING -> FAILED_TEMP (i.e., transitions from ROLLING_BACK and
    STARTING are not supported)

    In addition, as the current ``_get_affected_resources`` doesn't work
    correctly when there are no updated resources, this patch modify
    ``utils.py`` [2] to fix it and update the tests [3] depending on
    ``utils.py``.

    [1] https://www.etsi.org/deliver/etsi_gs/NFV-SOL/001_099/003/03.05.01_60/gs_NFV-SOL003v030501p.pdf
    [2] tacker/vnflcm/utils.py
    [3] tacker/tests/unit/conductor/test_conductor_server.py

    Change-Id: I54aa967be7903c064433f01adf0f99074577a8da
    Closes-bug: #1924917
    Signed-off-by: Hiromu Asahina <email address hidden>