Open Stack

On 08/02/2018 06:27 PM, Jay Pipes wrote:
> On 08/02/2018 06:18 PM, Michael Glasgow wrote:

>> More generally, any time a service fails to deliver a resource which it is
>> primarily designed to deliver, it seems to me at this stage that should
>> probably be taken a bit more seriously than just "check the log file, maybe
>> there's something in there?"  From the user's perspective, if nova fails to
>> produce an instance, or cinder fails to produce a volume, or neutron fails to
>> build a subnet, that's kind of a big deal, right?
>>
>> In such cases, would it be possible to generate a detailed exception object
>> which contains all the necessary info to ascertain why that specific failure
>> occurred?
>
> It's not an exception. It's normal course of events. NoValidHosts means there
> were no compute nodes that met the requested resource amounts.

I'm of two minds here.

On the one hand, you have the case where the end user has accidentally requested 
some combination of things that isn't normally available, and they need to be 
able to ask the provider what they did wrong.  I agree that this case is not 
really an exception, those resources were never available in the first place.

On the other hand, suppose the customer issues a valid request and it works, and 
then issues the same request again and it fails, leading to a violation of that 
customers SLA.  In this case I would suggest that it could be considered an 
exception since the system is not delivering the service that it was intended to 
deliver.

Chris