Maintenance zone support for suspending provider

[slemrmartin]

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1455145
Issue: ManageIQ/manageiq#17489

Suspending provider consists of moving provider (ExtManagementSystem) to maintenance zone.

Maintenance zone will be created in Zone.seed and identified by association to region.
Name of zone will be generated as maintenance_#{uuid}. This zone will have visible flag set to false, which will be handled by PRs in UI and API.

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This is an alternative to #222, where zone is supposed to be identified by unique name.

• (dependent) Suspend providers manageiq#17452

[slemrmartin]

cc @agrare @Fryguy @bdunne @Ladas @carbonin

[bdunne]

👍 I prefer this approach. I would probably put Zone.update_all(:visible => true) in the same migration that adds the column.

[Ladas]

@bdunne I believe this is the last day we can merge it? So can you? (btw. I believe it was already commented that we should not mix data and schema migrations together)

[Ladas]

👍

[agrare]

@slemrmartin what does the corresponding core PR look like if the maintenance zone name isn't constant?
e.g. here https://github.com/ManageIQ/manageiq/pull/17452/files#diff-d8c450b508868941c2b0c5884e718324R129 where all we know is the maintenance zone name.
Are you going to have to do some query for Zone.where(:visible => :false) and cache that name?

[bdunne]

We should probably implement a Zone.maintenance_zone method that caches on the class

[carbonin]

I know this was here from the original PR, but I'm not a fan of the name of this column.

backup makes it sound like it will get used if there is a problem rather than as a part of normal operation (i.e. resume).

I haven't been able to come up with anything I'm really happy with, but here are some of my thoughts:

• runtime_zone
• zone_before_pause

Any other ideas? @agrare @Fryguy ?

[slemrmartin]

original_zone?

[carbonin]

I also considered original_zone or last_zone, but really this is something specific to pausing an ems so I would rather make that obvious from the attribute name.

Spoke about it for a bit with @jrafanie, our "Master Namer of Things" and we came up with zone_when_paused. How about that?

[jrafanie]

Naming is hard

[agrare]

Don't want to bikeshed too much about the name, but zone_when_paused would be the maintenance zone, I'd think zone_before_pause would be better than zone_when_paused

[carbonin]

Generally, I'm with @bdunne. This looks like a much better approach than a rename. I'll 👍 if we can come up with a better name for the backup_zone column.

[slemrmartin]

@slemrmartin what does the corresponding core PR look like if the maintenance zone name isn't constant?
e.g. here https://github.com/ManageIQ/manageiq/pull/17452/files#diff-d8c450b508868941c2b0c5884e718324R129 where all we know is the maintenance zone name.
Are you going to have to do some query for Zone.where(:visible => :false) and cache that name?

@agrare there can be used Zone.maintenance_zone&.name (which will be changed to find zone by region.maintenance_zone).
Flag "visible" will be used by UI and API and can be more used for hide it from user's eyes.

[slemrmartin]

We should probably implement a Zone.maintenance_zone method that caches on the class

It's is implemented in dependent PR, only has to be changed according to this PR

[agrare]

@slemrmartin @bdunne 👍

[miq-bot]

Checked commits slemrmartin/manageiq-schema@a73880e~...eab842d with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
5 files checked, 2 offenses detected

db/migrate/20180618084054_init_zones_visibility.rb

• ❗ - Line 13, Col 12 - Rails/SkipsModelValidations - Avoid using update_all because it skips validations.
• ❗ - Line 7, Col 12 - Rails/SkipsModelValidations - Avoid using update_all because it skips validations.

[agrare]

LGTM, @carbonin / @bdunne thoughts?