Hi guys, I recently wrote a barclamp to update system packages on deployed nodes. We will need this for SUSE Cloud to be able to deploy maintenance / security updates to customers. However, due to the nature of the barclamp, it isn't supposed to run all time. Instead, a cloud operator wants to trigger the federated update for a specific set of machines at a specific point in time.
In essence, this means the wrapped cookbook is a one-shot one. With only Chef-means, you would simply remove the updater recipe from a node's run-list afterwards [1]. However, since Crowbar doesn't store the run-list in the node object but a special role (crowbar-$FQDN) we seem to run out of luck with only chef means. Chef-client running on a node simply lacks the rights to modify a global role (i.e. remove a recipe from the role's run-list). The simplest approach would be to just use a special attribute in the cookbook that acts as the 'actually-do-something' switch, e.g. "defaults[:updater][:first-run] = true" which is then set to false after the recipe was applied. This way, the barclamp would end up in "ready" state showing success. But it's totally unclear for the user that the thing is actually one-shot or that he has to edit / re-apply the proposal. So the idea was to deactivate the proposal immediately after it was applied so that it is obvious to the admin that he has to re-apply it (with a potentially different set of nodes). A first shot was to add a callback that is run after ServiceObject#apply_role [2],[3]. However, we won't end up in ready state thus no green bubble, thus there's no mechanism left to actually notify about success or failure. This could be mitigated somewhat with a new state that signals "I ran successfully and disabled myself". It will be very likely that we will have more one-shot barclamps in the future (e.g. evacuate-compute-node), therefore I'd like to get some feedback before going further in any direction. [1] https://github.com/cookbooks/one-shot/blob/master/recipes/default.rb [2] https://gist.github.com/saschpe/5763924 [3] https://github.com/SUSE-Cloud/barclamp-updater/blob/master/crowbar_framework/app/models/updater_service.rb#L41 -- Sascha Peilicke SUSE Linux GmbH, Maxfeldstr. 5, D-90409 Nuernberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer HRB 16746 (AG Nürnberg) _______________________________________________ Crowbar mailing list Crowbar@dell.com https://lists.us.dell.com/mailman/listinfo/crowbar For more information: http://crowbar.github.com/
