remove devices before min-part-hours requires --force

I just reproduced the bug. Working on it

I am a newbie so please point out anything that is not following the requirement. Basically I followed the suggestion and modified the swift/cli/ringbuilder.py and swift/common/ring/builder.py to fix the bug.

I already tested it on my SAIO and it is fine.

Jethro, thanks for your patch. In openstack, patches are always sent to gerrit for code review. You can learn more about the development process here: http://docs.openstack.org/infra/manual/developers.html

Thanks for the info, I believe now the patch is correctly submitted.

> But it'd be better to leave this kind of validation in the Builder code and
> not have pre-rebalance checks like this in the cli code - i'm sure existing
> tests for the builder would have detected this sort of mistake but not all
> scenarios like this get hit through the rinbuilder cli tests.

This is still broken, there's other situations besides device removal that might make it *look* like rebalance isn't going to do anything - but if we would just let it *try* it would work as expected without the --force flag.

Remove the check in the cli code, and expose the error by detecting if

1) no parts have moved
2) the min part hours looks locked (same check as we have already sans the bit about the remove_devices)

If we just let the Builder do it's job this bug would be fixed.

Associated fix in https://review.openstack.org/#/c/326967/

Reviewed: https://review.openstack.org/326967
Committed: https://git.openstack.org/cgit/openstack/swift/commit/?id=47901ea4d7fe5ffbbb826d561ad4a02dc4ea8f4a
Submitter: Jenkins
Branch: master

commit 47901ea4d7fe5ffbbb826d561ad4a02dc4ea8f4a
Author: Christian Schwede <email address hidden>
Date: Wed Jun 8 09:20:26 2016 +0000

    Rebalance with min_part_seconds_left > 0

    As described in bug #1558754 a rebalance after removing a device fails
    if min_part_seconds_left > 0, despite the note that a rebalance should
    remove partitions from removed devices on the next run.

    This patch skips the early exit, and lets the builder itself handling
    the rebalance. Partitions that shouldn't move now are still not moved
    (except for removed devices), and there is still a warning if no
    partition has been moved due to the fact that min_part_hours did not yet
    pass.

    A small test has been added to ensure rebalancing after removing a
    device works without using the --force option (tests fails on current
    master). Another test ensures that a rebalance after a recent change
    (for example increasing a device's weight) does not move partitions and
    still reports the former warning message.

    Closes-Bug: 1558754
    Change-Id: I083022d066338cbe6234bab491c7a8e8e0a7b517

Fix proposed to branch: stable/newton
Review: https://review.openstack.org/433567

This issue was fixed in the openstack/swift 2.13.0 release.

Reviewed: https://review.openstack.org/433567
Committed: https://git.openstack.org/cgit/openstack/swift/commit/?id=9c8c7e8a55d30a84407a7c55ec83292c2b836df6
Submitter: Jenkins
Branch: stable/newton

commit 9c8c7e8a55d30a84407a7c55ec83292c2b836df6
Author: Christian Schwede <email address hidden>
Date: Wed Jun 8 09:20:26 2016 +0000

    Rebalance with min_part_seconds_left > 0

    As described in bug #1558754 a rebalance after removing a device fails
    if min_part_seconds_left > 0, despite the note that a rebalance should
    remove partitions from removed devices on the next run.

    This patch skips the early exit, and lets the builder itself handling
    the rebalance. Partitions that shouldn't move now are still not moved
    (except for removed devices), and there is still a warning if no
    partition has been moved due to the fact that min_part_hours did not yet
    pass.

    A small test has been added to ensure rebalancing after removing a
    device works without using the --force option (tests fails on current
    master). Another test ensures that a rebalance after a recent change
    (for example increasing a device's weight) does not move partitions and
    still reports the former warning message.

    Closes-Bug: 1558754
    Change-Id: I083022d066338cbe6234bab491c7a8e8e0a7b517

This issue was fixed in the openstack/swift 2.10.2 release.