This doc was originally written in the middle of Terraform v0.12
development while some refactoring was already in progress. Here we update
those parts to refer to where the relevant functionality finally landed,
and also update some things that we did not anticipate changing at the
time but ended up having to be changed during the v0.12 development
anyway.
For a while now we've been gathering some codebase-level docs that felt
out-of-place on the main Terraform website (since they are about the
implementation, not usage) but we had no existing suitable place to put
them.
In order to make this information more available (and, hopefully, more
likely to stay up-to-date as we change things), here we'll establish the
"docs" directory as a place to keep documentation aimed at those who are
working on code changes to the Terraform Core codebase.
User-oriented docs should never appear in this directory. The Terraform
website is always the better place for those. The set of docs here is
rudimentary to start and we'll see if it makes sense to expand and
reorganize it over time based on the experience with having these initial
docs available.
In the terraform state documentation the verb "map" is widely used to
describe the relationship between an item in the state and in the real world
whereas the verb "attach" is not used anywhere.
For 0.11 I just specified the naming rules; for 0.12, I added some info about
referencing values and tightened up the layout of the optional arguments.
This commit also syncs up descriptions of `depends_on`.
Add the (forces new resource) annotation to the diff output for provider
tests failures when we can. This helps providers narrow down what might
be triggering changes when encountering test failures with the new SDK.
'legacy' doesn't seem to be a thing anymore, and we were missing some
of the other values for -type. Also -no-color doesn't seem to be
relevant to this command.
1. The double "$" in the template confuses readers
2. As far as I can tell the variable "count" is not used either in this example
(it is in the next example though)
When a resource type schema includes dynamically-typed attributes we can't
do any automatic conversion from flatmap to JSON because we don't know
how to interpret the keys that start with the dynamically-typed
attribute's prefix.
To work around that, we'll instead just ask the SDK to do a no-op upgrade
(current and target versions are the same) which will convert from flatmap
to JSON using the SDK's own logic as a side-effect.
This situation should rarely arise in real-world use, but it ends up being
very important for the helper/resource provider test harness because it
is forced to lower the state back to flatmap repeatedly after every step
in order to run legacy checking and processing code.
The previous commit added this flag but did not implement it. Here we
implement it by adjusting the shape of schema we return to Terraform Core
to mark the attribute as untyped and then ensure that gets handled
correctly on the SDK side.
When running in v0.12-and-higher mode, this will cause the SDK to report
the type of the attribute as "any", effectively skipping type checking
on the Core side altogether and checking only in the SDK and provider
code.
The practical impact of this is to restore the v0.11-style checking
behavior of allowing object values to be missing certain attributes as
long as they are marked as optional in the schema. The SDK can do this
because it uses a unified schema model for both object values and nested
blocks, while Terraform Core only supports the idea of "optional" when
talking about attributes in nested blocks.
This is a continuation of the pile of workarounds that also includes
the ConfigMode and AsSingle fields, allowing providers to selectively opt
out of new v0.12 behaviors in situations where they conflict with
decisions made in the design of the providers in our old world where
Terraform Core delegated _all_ validation to providers.
This is designed as an opt-in so that we can limit its impact only to
specific cases where it's needed and minimize the risk of regressions
elsewhere. Providers should use this sparingly only in situations where
prevailing usage disagrees with the new expectations of Terraform Core in
v0.12.
This commit only adds the flag, and does not implement any behavior for it
yet. That means this commit can exist in both the v0.11 and v0.12
codebases, allowing for API compatibility. A subsequent commit for v0.12
(not included in v0.11) will then implement this behavior.
This includes a fix to prevent unintentional infinite recursion when
trying to unify multiple object types to a single type for conversion to
list(any).
Sadly I wasn't able to reproduce the problem as reported (in #20728), so
therefore I wasn't able to write a Terraform test for it, but I have
confirmed that the cty behavior here was incorrect anyway (recursively
calling the same function we're already in with the same arguments is
clearly not productive) and so this change will allow whatever situation
that was to terminate with a type conversion error, rather than causing a
stack overflow.
It's likely that there is another bug lurking under this, since the
problematic code here was supposed to be unreachable, but avoiding the
crash is the priority for now. If the problem re-surfaces then it should
at least be an error message with some additional context about what the
goal of the caller was.
This also includes an unrelated fix for the gocty package, which doesn't
affect Terraform because it makes very little use of that package.
The templatefile function only has two arguments, so ArgErrorf can be
called with only zero or one as the argument index. If we are out of
bounds then HCL itself will panic trying to build the error message for
this call when called as an HCL function.
Unfortunately there isn't really a great layer in Terraform to test for
this class of bug systematically, because we are currently testing these
functions directly rather than going through HCL to do it. For the moment
we'll just live with that, but if we see this class of error arise again
we might consider either reworking the tests in this package to work with
HCL expression source code instead of direct calls or adding some
additional tests elsewhere that do so.
Due to these tests happening in the wrong order, removing an object from
the end of a sequence of objects would previously cause a bounds-check
panic.
Rather than a more severe rework of the logic here, for now we'll just
introduce an extra precondition to prevent the panic. The code that
follows already handles the case where there _is_ no new object (i.e. the
"old" object is being deleted) as long as we're able to pass through this
type-checking logic.
The new "JSON list of objects - removing item" test covers this problem
by rendering a diff for an object being removed from the end of a list
of objects within a JSON value.
It's important to preserve the provider address because during the destroy
phase of provider tests we'll use the references in the state to determine
which providers are required, and so without this attempts to override
the provider using the "provider" meta-argument can cause failures at
destroy time when the wrong provider gets selected.
(This is particularly acute in the google-beta provider tests because that
provider is _always_ used with provider = "google-beta" to override the
default behavior of using the normal "google" provider.)
* docs: elaborate on supported remote backend versions
This PR adds a few lines to the docs to indicate which commands are
supported by what version of the remote backend and it makes a
recommendation about which version to use.
* Clarify remote state storage w/ TFE [skip ci]
Specifically, that this is the backend to use with remote state (all
tiers) and Free-Tier vs. Enterprise tiers differ in remote operations
* website: Arrange remote backend info differently
The hcldec package has no awareness of the dynamic block extension, so the
hcldec.Variables function misses any variables declared inside dynamic
blocks.
dynblock.VariablesHCLDec is a drop-in replacement for hcldec.Variables
that _is_ aware of dynamic blocks, returning all of the same variables
that hcldec would find naturally plus also any variables used inside
the dynamic block "for_each" and "labels" arguments and inside the
nested "content" block.
This includes improved functionality for HCL's "dynamic block extension",
which will allow us (in a subsequent commit) to properly detect
dependencies inside nested "dynamic" blocks, where currently they get
missed.
For this commit though, we just upgrade HCL to a version that includes it
and make a small change to our "lang" package to align with an upstream
renaming.
Martin Atkins