On Tue, Jun 17, 2014 at 6:39 AM, Andrew Wilkins < [email protected]> wrote:
> Hi all, > > I've started looking into fixing > https://bugs.launchpad.net/juju-core/+bug/1215579. The gist is, we > currently set private-address in relation settings when a unit joins, but > never update it. > > I've had some preliminary discussions with John, William and Dimiter, and > came up with the following proposal: > https://docs.google.com/a/canonical.com/document/d/1jCNvS7sSMZqtSnup9rDo3b2Wwgs57NimqMorXr9Ir-o/edit > > If you're a charm author, particularly if you work on "proxy charms", > please take a look at this and let me know of any concerns or suggestions. > I have opened up comments on the doc. > > In a nutshell: > - There will be a new hook, relation-address-changed, and a new tool > called address-get. > - The hook will be called when the relation's address has changed, and > the tool can be called to obtain the address. If the hook is not > implemented, the private-address setting will be updated. Otherwise it is > down to you to decide how you want to react to address changs (e.g. for > proxy charms, probably just don't do anything.) > I think that what the proposal says is subtly different: that is, that we *will* update the private-address setting for that foo relation at the start of the foo-relation-address-changed hook, but that it won't be propagated further until that hook is committed. The upshot is that if you're *not* a proxy charm, you can *probably* ignore the relation-address-changed hook [0]; but if you *are* a proxy charm, you must (almost) certainly overwrite the new private-address setting with that of the endpoint you're proxying. IMO this behaviour is more consistent and predictable than behaving differently depending on whether or not a particular hook is implemented. Cheers William [0] some interfaces have their own language -- say "host" -- and they'll have to be responsible for updating themselves. > > Thanks, > Andrew > > -- > Juju-dev mailing list > [email protected] > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/juju-dev > >
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