[openstack-dev] [Magnum][Heat] Expression of Bay Status
jay.lau.513 at gmail.com
Wed Mar 11 09:27:22 UTC 2015
2015-03-10 23:21 GMT+08:00 Hongbin Lu <hongbin034 at gmail.com>:
> Hi Adrian,
> On Mon, Mar 9, 2015 at 6:53 PM, Adrian Otto <adrian.otto at rackspace.com>
>> Magnum Team,
>> In the following review, we have the start of a discussion about how to
>> tackle bay status:
>> I think a key issue here is that we are not subscribing to an event feed
>> from Heat to tell us about each state transition, so we have a low degree
>> of confidence that our state will match the actual state of the stack in
>> real-time. At best, we have an eventually consistent state for Bay
>> following a bay creation.
>> Here are some options for us to consider to solve this:
>> 1) Propose enhancements to Heat (or learn about existing features) to
>> emit a set of notifications upon state changes to stack resources so the
>> state can be mirrored in the Bay resource.
> A drawback of this option is that it increases the difficulty of
> trouble-shooting. In my experience of using Heat (SoftwareDeployments in
> particular), Ironic and Trove, one of the most frequent errors I
> encountered is that the provisioning resources stayed in deploying state
> (never went to completed). The reason is that they were waiting a callback
> signal from the provisioning resource to indicate its completion, but the
> callback signal was blocked due to various reasons (e.g. incorrect firewall
> rules, incorrect configs, etc.). Troubling-shooting such problem is
> generally harder.
I think that the "heat convergence" is working on the issues for your
>> 2) Spawn a task to poll the Heat stack resource for state changes, and
>> express them in the Bay status, and allow that task to exit once the stack
>> reaches its terminal (completed) state.
>> 3) Don’t store any state in the Bay object, and simply query the heat
>> stack for status as needed.
>> Are each of these options viable? Are there other options to consider?
>> What are the pro/con arguments for each?
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Jay Lau (Guangya Liu)
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