On Wed, May 21, 2014 at 10:53 PM, Tudor Rogoz <ro...@adobe.com> wrote:
> Hi, > > > I'm new to juju and I just started to work on a new charm and I'm not > sure how to solve several issues.I will appreciate any advice on this. > > > The topology that I want to achieve is described bellow: > > > My service (i will call it application service) "strongly" depends on > the mongodb service [0].This means that the application service cannot be > installed and started without a mongo previously configured for storing the > application data.The problem is that when I'm deploying the service, > automatically the install, config-service and start hooks will be > triggered, but at this point my service cannot know about mongo service > because a relation between the 2 services is not established yet.So, it's > impossible for me to perform the product installation in the install > hook.An ugly workaround would be to perform the installation in the > relation-joined/relation-cahnged hook, but this would be my last > option.Even in this case the service unit will appear as "started" after > the start hook ends, but nothing will actually run there. > Stuart answered the main points; I'd like to add one more thing: we have some work scheduled to enable charms to report that they are not yet ready. The driver is exactly what you're describing: applications that require a relation to be usable. > I would like for the charm to support the following scenario. > > 1/I deploy the application service > > 2/ the service unit remains in a pending state before the installation > hook will run because the service unit has no access to a mongo service > > 3/ deploy the mongo service which successfully starts > > 4/ add a relation between mongo and application service. The app service > will get the mongo connection information > > 5/ application service installation starts (the install hook is > unblocked), and successfully starts > > > > Another problem that i have is the following: > > For example, one of my application units is getting the connection > details from a specific mongodb unit while running the relation hook, were > i can store the specific information for using it in another hook? Is there > anything implemented in juju for this, or I should write the information in > a file and store it on disk and read from there when is need it? > > > [0] https://github.com/charms/mongodb > <https://github.com/charms/mongodb> > charms/mongodb · GitHub > mongodb - Mirror of juju charm, pull requests and modifications welcome! > Read more... <https://github.com/charms/mongodb> > > > > Thanks a lot, > > Tudor > > > > -- > Juju mailing list > Juju@lists.ubuntu.com > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/juju > >
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