[chef] Re: Re: Re: Double converge, blocking on search, event-driven chef-client?

[Lamont Granquist < >]

On Thu Oct 2 09:52:34 2014, Justin Dossey wrote:
> 4. (paraphrased) Use push jobs to notify nodes when the
> infrastructure is ready for them to converge. The very first
> sentence on the Chef Push Jobs page is "Chef push jobs is an
> extension of the Chef server that allows jobs to be run against
> nodes independently of a chef-client run." We are talking about
> triggering individual resources within a cookbook within a
> chef-client run, so push jobs don't really address this issue at
> all. Also, it would appear that push jobs were meant to be
> triggered by administrators and not by the chef-client. While I'm
> sure it would be possible to set things up in such a way that a
> successful initial converge could trigger a push job, such an
> implementation diverges considerably from the role of push jobs as
> designed.
Triggering a single individual resource is not a pattern we're likely to 
ever support[*].  We have support for override run lists which you can 
use to do a software deployment or configure nagios or whatever and not 
have to go through and create all your home directories for your admins 
and reapply all your sysctl configuration and ssh_known_hosts entries 
and orthogonal stuff you don't care about.  Aside from whatever the docs 
might state, that is certainly a use case for push jobs.  I also don't 
know where the idea was that its only supposed to be kicked off by an 
administrator is coming from, since it is designed to be an 
orchaestration agent. Based on the design you should be able to have 
edge clients (webserver and whatnot) send a push jobs notification that 
amount to announcing that they've newly been built, this could then be 
used to kick off chef-client override runlists on nagios host to have 
them hit search and add the new host to monitoring.  I'm not certain how 
polished push jobs is for all of that right now, but its definitely the 
tool you want for the use case you describe.

[*] you could extract the resource you want to signal and put it in its 
own stand-alone recipe (which you could include_recipe from the run_list 
you normally use) and then only trigger that one-resource-recipe, so I 
guess we do support that if you do the work to extract it...   it won't 
work like a magic cross-server resource notification though.