Orphan addressing / targeting

[phinze]

Instead of trying to skip non-targeted orphans as they are added to
the graph in OrphanTransformer, remove knowledge of targeting from
OrphanTransformer and instead make the orphan resource nodes properly
addressable.

That allows us to use existing logic in TargetTransformer to filter out
the nodes appropriately. This does require adding TargetTransformer to the
list of transforms that run during DynamicExpand so that targeting can
be applied to nodes with expanded counts.

Fixes #4515
Fixes #2538
Fixes #4462

[StefanSmith]

I'm finding that with in releases since about 0.6.6, when I "apply -target=...", orphaned resources are destroyed. Does 4574 change the behaviour such that resources in the state file which are no longer defined in the *.tf files will be ignored rather than destroyed on "apply"?

[phinze]

Alright @mitchellh / @jen20 this should be ready for review. Confirmed it fixes several open bugs and included a covering test for each one.

[mitchellh]

LGTM! I still think at some point we should just measure twice and cut once the targeting syntax to make sure we can get it fully right and test the full supported syntax. But this doesn't appear to introduce any except make the old one work properly so LGTM.

[phinze]

Thanks for the review! Merging. 🚢

I still think at some point we should just measure twice and cut once the targeting syntax to make sure we can get it fully right and test the full supported syntax.

What's there in ResourceAddress has been specced out, docced, and tested pretty extensively. We need to get the same syntax ported over to terraform taint and we need to come up with a story for exclude/inverse targeting (#2253), but other than that I wasn't aware of anything missing. Can you clarify a bit more?

[josephholsten]

So excited to see this merged. Will be verifying this fixes our issues today.

[jjshoe]

Can confirm this works as of e865c34

[ghost]

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