Extend InventoryCollectionDefault::NetworkManager with network_groups

[miha-plesko]

With this commit we implement a class function that is needed when implementing graph inventory refresh for NetworkManager that support NetworkGroup inventory object. The new network_groups function provides hash of common properties that are needed by persister.

@Ladas I've assigned you since I remember you being in charge of introducing graph refresh. Please let me know if someone else should be assigned instead.

@miq-bot add_label enhancement
@miq-bot assign @Ladas

/cc @gberginc

[miq-bot]

Checked commit miha-plesko@254c9d7 with ruby 2.3.3, rubocop 0.47.1, and haml-lint 0.20.0
1 file checked, 0 offenses detected
Everything looks fine. 👍

[Ladas]

Looks good. 👍

For the NetworkGroup itself, I am still not sure whether it gets things clearer or not. It acts the same as CloudNetwork now. So maybe we should keep using CloudNetwork model, until the behavior will become different?

[Ladas]

@miq-bot assign @blomquisg

[miha-plesko]

I'm not sure what the rationale to use NetworkGroup was either, but I think Nuage guys are using miq in production already (not 100% sure about this). I don't think I have balls to go change this without consulting them first 😄

My plan would be to implement graph inventory refresh that works exactly like their current legacy refresher and then drop the legacy refresher completely. Then, having only one fansy refresher, I'd go into changing models if requested. Sounds good?

[miha-plesko]

@blomquisg I think Ladas and myself converged to the point where only merge button needs to be pressed. Naturally, if you have any comments, I'd be glad to hear them.

[blomquisg]

Punting over to @agrare because I think he's been following more of the general networking discussions than I have.

[agrare]

This looks good for parity with current refresh
If we want to merge NetworkGroup and CloudNetwork that will need a migration to move existing data. If this is something you want to do we should do it soon before schema freeze (a few weeks).