Comment 2 for bug 1694132
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| Dmitrii Shcherbakov (dmitriis) wrote Re: [2.2b4] No way to re-query tags (machine, storage) from MAAS after model creation - have to create a new model | #2 |
Something tells me that it may have to be even more generic.
In general, we might query information about provider-specific information like network spaces, storage tags (or other storage-related information), availability zones, security groups (OpenStack) and possibly other information that we haven't thought about yet:
https:/
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This is a case of a distributed metadata storage and I can think of at least three ways of doing that:
1) manual sync - give a user manual control over that. Trade-off: manual work vs complexity of code;
2) polling - requery automatically in Juju with a subjective pre-defined policy. Trade-off: assumptions and policy maintenance;
3) watchers (event subscription) - subscribe to provider-specific events and update as soon as the new information is available. Trade-off: asynchronous code, providers do not support emission of events and client subscription to those in general (they would have to expose an interface like etcd, Zookeeper, consul etc.).
Realistically, I think it is right that we will go with the first approach. Could be something worth documenting though as people may have different expectations from Juju.