[Linux-HA] resource group design question (2)

[Daniel X Moore]

Andrew Beekhof wrote:
>> But this prevents us from adding/removing sub-resources
>> effectively as HB knows nothing of them.
> 
> in what way does HB prevent this?
> if you change the value then we'll tell your resource the new value.

The _new_ value, yes. Not the old, so the plugin doesn't know what to 
stop (if any).

Also, there's no way for the program which makes the change to 
synchronize against the plugin starting/stopping the sub-resource. eg: 
you add a sub-resource, but there's no way to ask HB when that change 
has actually taken effect.

>>> I'm really interested in that use case. It's morning here and I
>>> can only imagine that you want to dynamically order the way the
>>> parts are handled.
>> Each resource within the group needs a number of sub-resources
>> started/stopped and the sequence is mixed up between the resources when
>> starting/stopping everything together.
> 
> define "mixed up"

Each sub-resource has a number of phases for start & stop. We need to 
run one phase for each sub-resource, then the next phase for each 
sub-resource etc. -> we need to know the list of sub-resources so we can 
process them together.

>> Hope this explains it!
> 
> not really - but maybe i'm thick

more likely, I'm not explaining it properly. It'd be easy with a 
white-board.

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