Ton, could you repost this as a new thread? It has very little to do with the referenced thread.
Excerpts from Ton Ngo's message of 2014-03-17 12:10:33 -0700: > I would like to revisit with more details an idea that was mentioned in the > last design summit and hopefully get some feedback. > > The scenario is troubleshooting a failed template. > Currently we can stop on the point of failure by disabling rollback: this > works well for stack-create; stack-update requires some more work but > that's different thread. In many cases however, the point of failure may > be too late or too hard to debug because the condition causing the failure > may not be obvious or may have been changed. If we can pause the stack at > a point before the failure, then we can check whether the state of the > environment and the stack is what we expect. > The analogy with program debugging is breakpoint/step, so it may be useful > to introduce this same concept in a stack. > > The usage would be something like: > -Run stack-create (or stack-update once it can handle failure) with one or > more resource name specified as breakpoint > -As the engine traverses down the dependency graph, it would stop at the > breakpoint resource and all dependent resources. Other resources with no > dependency will proceed to completion. > -After debugging, continue the stack by: > -Stepping: remove current breakpoint, set breakpoint for next resource > (s) in dependency graph, resume stack-create (or stack-update) > -Running to completion: remove current breakpoint, resume stack-create > (or stack-update) > > Some other possible uses for this breakpoint: > - While developing new template or resource type, bring up a stack to a > point before the new code is to be executed > - Introduce human process: pause the partial stack so the user can get the > stack info and perform some tasks before continuing > > Some issues to consider (with initial feedback from shardy): > - Granularity of stepping: resource level or internal steps within a > resource > - How to specify breakpoints: CLI argument or coded in template or both > - How to handle resources with timer, e.g. wait condition: pause/resume > timer value > - New state for a resource: PAUSED > > Thanks. > > Ton Ngo, > _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
