One-way communication in relation-get (was Re: Juju feedback from the Launchpad Yellow Squad)

[Kapil Thangavelu]

Excerpts from Gary Poster's message of Wed Feb 15 14:43:43 -0500 2012:
> On 02/15/12 13:30, Graham Binns wrote:
> 
> >   * The one-way communication aspect of relation-set was surprising (so I
> >     can relation-set foo=bar but I can never find out later on what I've
> >     already told a relation about config options).
> >     It would be great if there were a utility to retrieve whatever had
> >     been sent to a relation. This would also be a nice way of caching
> >     things for Charms :).
> 
> hazmat pointed out on IRC that this is possible now, and that 
> "relation-get -h" gives some direction on how.  Putting "relation-get 
> -h" and https://juju.ubuntu.com/docs/charm.html#hook-environment 
> together, if you want to get the value for "mykey" that you set in a 
> relation, you can use "relation-get mykey $JUJU_UNIT_NAME".
> 
> hazmat continued, "it needs  documentation, and it looks like it should 
> be a switch so a key doesn't need to be specified."

fwiw, I found that the current implementation supports not passing an explicit 
key via usage of '-' as the key name to get all key/values.

-k