The differences between the implicit and explicit modes of passing
provider configurations between modules are significant enough to warrant
giving these approaches different names and describing them separately.
This also includes documentation of the current limitation discussed in
#16612, where explicit passing requires a proxy configuration block even
for a _default_ provider configuration, because that limitation is being
accepted for the 0.11.0 release to limit scope.
The initial pass of this section had some remaining ambiguities, so this
is a second revision that attempts to use terminology more consistently
and to not some additional behaviors that were not described in the
initial version.
The modules mechanism has changed quite a bit for version 0.11 and so
although simple usage remains broadly compatible there are some
significant changes in the behavior of more complex modules.
Since large parts of this were rewritten anyway, I also took the
opportunity to do some copy-editing to make the prose on this page more
consistent with our usual editorial voice and to wrap the long
lines.
Terraform modules encapsulate their resources, and dependencies can only
be expressed through outputs, which wasn't clear to me in the existing
documentation. I'm hoping a small change will make that more explicit.
Martin Atkins