non subordinate container scoped relations broken

[Kapil Thangavelu]

on 1.21, i was trying out container scoped relations for non subordinate relations, it appears they are broken and trigger an infinite restart in the unit agent. i have a few use cases for these fwiw (units on the same host communicating to coordinate).

[Kapil Thangavelu (hazmat)]

i was able to workaround in charm land, my only paying attention to the units with the same private ip address.

[Kapil Thangavelu (hazmat)]

the bigger issue is just that this effectively sticks the uniter into an endless restart loop, so should be disallowed if its not supported.

[Menno Finlay-Smits (menno.smits)]

This could be related to the recent env UUID migrations for the relations or relationscopes collections so I'm going to investigate.

Kapil: do you have a minimal way to reproduce the problem?

[Menno Finlay-Smits (menno.smits)]

I've been looking at this today.

The problem isn't specific to 1.21. I can reproduce it on 1.20.11 and even 1.19.4. It looks like non-subordinate-charm container relations have been broken for some time.

[Menno Finlay-Smits (menno.smits)]

To reproduce:

juju bootstrap
juju deploy --repository ~/path/to/repo local:container-scoped-relations-provider
juju deploy --repository ~/path/to/repo local:container-scoped-relations-requirer --to 1
juju add-relation juju add-relation container-scoped-relations-provider container-scoped-relations-requirer

At this point both the provider and requirer uniters continually die and restart, reporting "ModeAbide: service is not a subordinate".

As far as I can tell, when EnterScope() is called as the relation is joined, subordinateOps() decides to create a subordinate unit, which doesn't seem like the right thing to do in this case.

I'm a little unsure of the desired behaviour here. I'll try to catch Will later on.

[Menno Finlay-Smits (menno.smits)]

I've talked to Will and apparently it shouldn't be possible (and doesn't really make sense) to have container scoped relations where neither endpoint is a subordinate service. The fix is to add an extra check to State.AddRelation(). State.InferEndpoints() also needs to be tweaked to ensure it doesn't suggest inappropriate relations.

I'm working on this now.

[Kapil Thangavelu (hazmat)]

re desired behavior, i'd imagine not going into restart loops would be
good, via explicitly support for the scenario (scope != subordinate) or
preventing the scenario by erroring during add-relation

On Fri, Nov 7, 2014 at 3:36 AM, Menno Smits <email address hidden>
wrote:

> To reproduce:
>
> juju bootstrap
> juju deploy --repository ~/path/to/repo
> local:container-scoped-relations-provider
> juju deploy --repository ~/path/to/repo
> local:container-scoped-relations-requirer --to 1
> juju add-relation juju add-relation container-scoped-relations-provider
> container-scoped-relations-requirer
>
> At this point both the provider and requirer uniters continually die and
> restart, reporting "ModeAbide: service is not a subordinate".
>
> As far as I can tell, when EnterScope() is called as the relation is
> joined, subordinateOps() decides to create a subordinate unit, which
> doesn't seem like the right thing to do in this case.
>
> I'm a little unsure of the desired behaviour here. I'll try to catch
> Will later on.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1382751
>
> Title:
> non subordinate container scoped relations broken
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/juju-core/+bug/1382751/+subscriptions
>

[William Reade (fwereade)]

yeah, the plan is to error on add-relation

[Menno Finlay-Smits (menno.smits)]

http://reviews.vapour.ws/r/377/

[Curtis Hovey (sinzui)]

1.22 (master) is fixed with https://github.com/juju/juju/pull/1075

[Menno Finlay-Smits (menno.smits)]

Backported fix to 1.20 in https://github.com/juju/juju/pull/1159 (0817a0ba3b1b228423ccaf43833903b4c44b9a97)

[Simon Davy (bloodearnest)]

The fix for this seems to have unintentionally broken relating 2 subordinates via scoped relations.

Have filed a new bug: https://bugs.launchpad.net/juju-core/+bug/1396625