Deprecate the app_engine sub-block of google_project, and create a
google_app_engine_application resource instead. Also, add some tests for
its behaviour, as well as some documentation for it.
Note that this is largely an implementation of the ideas discussed in
#2118, except we're not using CustomizeDiff to reject deletions without
our special flag set, because CustomizeDiff apparently doesn't run on
Delete. Who knew? This leaves us rejecting the deletion at apply time,
which is less than ideal, but the only other option I see is to silently
not delete the resource, and that's... not ideal, either.
This also stops the app_engine sub-block on google_project from forcing
new when it's removed, and sets it to computed, so users can safely move
from using the sub-block to using the resource without state surgery or
deleting their entire project. This does mean it's impossible to delete
an App Engine application from a sub-block now, but seeing as that was
the same situation before, and we just papered over it by making the
project recreate itself in that situation, and people Were Not Fans of
that, I'm considering that an acceptable casualty.
Fix Dana's comments, one of which exposed a bug: we weren't actually
fixing the diff. Because resolveImage can return multiple formats, and
only returns a self_link if a self_link is passed in, it was diffing
more often than not against a self_link supplied in the config. We just
had a bug in our CustomizeDiff function that concealed this.
I added the resolvedImageSelfLink helper function to turn the output
from resolveImage into a self_link, which fixes the problem. It also has
the knock-on effect of fixing #2067 at the same time, which is nice. I
decided to add another function instead of just modifying resolveImage
to always return a self_link because I don't want to deal with the
backwards compatibility problems of changing how we're storing a bunch
of things in state this close to 1.19.0. And honestly, we should
probably just be storing the self_link always, _anyways_.
We don't need quite so many `GetOk`s since the client library will ignore any fields that are set to the zero value for that type. I left a few that involved error-handling or things that had to be set before other things, but this at least should make the code a bit nicer to look at.
Tests are passing except the ones that were already failing in CI.
Google Apps is a former name.
Also, I mention primary domain and domain alias. It seems I have
to use the primary domain. Otherwise, GCP replaces the field to the primary one.
And every time Terraform plan returns a diff about it.
I used domain alias for `members` arg in `google_project_iam_member`
resource. `terraform apply` was succeeded. However, when I run modify
other resources, I got a diff about the `google_project_iam_member`
resource.
