Fwd: [charms.reactive] http relation.available gets called on upgrade-charm hook, gives error.

[Merlijn Sebrechts]

Hi Cory


Thanks for the explanation. Is there a way to override the scope of the
http relation without forking the interface?



Kind regards
Merlijn

2015-10-26 18:21 GMT+01:00 Cory Johns <cory.johns at canonical.com>:

> Merlijn,
>
> You'll note that the docs for auto_accessors
> <https://pythonhosted.org/charms.reactive/charms.reactive.relations.html#charms.reactive.relations.RelationBase.auto_accessors>
> says that it's not a good idea to use with non-GLOBAL scoped relations, for
> this very reason.  The problem is that there's no way which unit's or
> service's host and port you are trying to get, since there could be many.
> If it's true that there should only be a single connected service on this
> relation, then you should switch it to  GLOBAL scope to indicate that.
> Otherwise, you need to be handling the possibility of multiple connected
> units explicitly.
>
> See
> https://github.com/johnsca/juju-relation-mysql/blob/master/provides.py#L74
> for an example of how an interface layer should handle multiple
> conversations.
>
> On Mon, Oct 26, 2015 at 5:58 AM, Merlijn Sebrechts <
> merlijn.sebrechts at gmail.com> wrote:
>
>> Hi all
>>
>>
>> I have the following piece of code that reacts to the
>> httprelation.available hook (called rest2jfed in this case):
>>
>>
>> @when('rest2jfed.available')
>> def setup_rest2jfed(rest2jfed):
>>     hostname = rest2jfed.host()
>>     port = rest2jfed.port()
>>     # Do some stuff with hostname and port
>>     hookenv.status_set('active', 'Ready')
>>
>>
>> This piece of code gets called on the upgrade-charm hook. This throws an
>> error because there is not a relationship context.
>>
>>   File "lib/charms/reactive/relations.py", line 88, in __accessor
>>     return self.get_remote(field)
>>   File "lib/charms/reactive/relations.py", line 308, in get_remote
>>     return self.conversation(scope).get_remote(key, default)
>>   File "lib/charms/reactive/relations.py", line 255, in conversation
>>     raise ValueError('Unable to determine default scope: no current hook
>> or global scope')
>>
>> Am I using this relation wrong or is this a bug?
>>
>>
>>
>> Kind regards
>> Merlijn
>>
>> --
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>>
>
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