The announcement post contains the information about the temporary
situation where not all of the providers are compatible yet. Linking there
rather than duplicating the information in the upgrade guide means we'll
be able to update in one place as the situation changes.
The new normalization should make preventing those changes unnecessary,
and will also prevent extra empty elements from being added when
resources are refreshed.
We are now allowing the legacy SDK to opt out of the safety checks we try
to do after plan and apply, and so in such cases the before/after values
in planned changes may be inconsistent with our usual rules.
To avoid adding lots of extra complexity to the diff renderer to deal with
these situations, instead we'll normalize the handling of nested blocks
prior to using these values.
In the long run it'd be better to do this normalization at the source,
immediately after we receive an object from a provider using the opt-out,
but we're doing this at the outermost layer for now to avoid risking
unintended impacts on other Terraform Core components when we're just
about to enter the beta phase of the v0.12.0 release cycle.
Now that we have an opt-out to let the legacy SDK return values that are
inconsistent with the new conventions for representing configuration,
various parts of Terraform must now be prepared to deal with
inconsistencies.
This function normalizes the most egregious inconsistencies relating to
the representation of nested blocks, freeing any recipient of its result
from worrying about these inconsistencies itself.
This includes a fix for the parsing of object for expressions in newline-
sensitive contexts like block bodies.
It also includes a change to the JSON syntax decoder that cause it to
consider an explicit null to be equivalent to a property not being set at
all when interpreting a property value as a nested block. (It was
previously doing tha only when interpreting the property value as an
attribute value.)
The upgrade guide had its last major upgrade while we were preparing for
the alpha releases. Now that the upgrade tool is more complete we can
describe the required changes in terms of that tool, and also add
additional information about provider upgrades.
We will revise this at least one more time before v0.12.0 final, but this
is an interim copy of the upgrade guide intended to help those who are
testing the beta releases.
This mirrors the change made for providers, so that default values can
be inserted into the config by the backend implementation. This is only
the interface and method name changes, it does not yet add any default
values.
We brought forward a new implementation of "terraform validate" that was
originally scheduled for a later release after finding that it would be
simpler than reworking the old implementation for new v0.12 assumptions,
but we didn't yet implement "terraform plan -validate-only" in spite of
it being mentioned in the updated docs for "terraform validate".
For now then, the documentation will make the weaker suggestion of running
"terraform plan" to validate a particular _run_ rather than a particular
_module_, which is the closest thing we have for now. At some point after
v0.12.0 we will evaluate whether a validate-only mode for "terraform plan"
(which could then run without configuring the providers at all) is needed.
Andriy Borodiychuk