The remote backend uses backend.ParseVariableValues locally only to decide
if the user seems to be trying to use -var or -var-file options locally,
since those are not supported for the remote backend.
Other than detecting those, we don't actually have any need to use the
results of backend.ParseVariableValues, and so it's better for us to
ignore any errors it produces itself and prefer to just send a
potentially-invalid request to the remote system and let the remote system
be responsible for validating it.
This then avoids issues caused by the fact that when remote operations are
in use the local system does not have all of the required context: it
can't see which environment variables will be set in the remote execution
context nor which variables the remote system will set using its own
generated -var-file based on the workspace stored variables.
During the 0.12 work we intended to move all of the variable value
collection logic into the UI layer (command package and backend packages)
and present them all together as a unified data structure to Terraform
Core. However, we didn't quite succeed because the interactive prompts
for unset required variables were still being handled _after_ calling
into Terraform Core.
Here we complete that earlier work by moving the interactive prompts for
variables out into the UI layer too, thus allowing us to handle final
validation of the variables all together in one place and do so in the UI
layer where we have the most context still available about where all of
these values are coming from.
This allows us to fix a problem where previously disabling input with
-input=false on the command line could cause Terraform Core to receive an
incomplete set of variable values, and fail with a bad error message.
As a consequence of this refactoring, the scope of terraform.Context.Input
is now reduced to only gathering provider configuration arguments. Ideally
that too would move into the UI layer somehow in a future commit, but
that's a problem for another day.
Previously we were using the experimental HCL 2 repository, but now we'll
shift over to the v2 import path within the main HCL repository as part of
actually releasing HCL 2.0 as stable.
This is a mechanical search/replace to the new import paths. It also
switches to the v2.0.0 release of HCL, which includes some new code that
Terraform didn't previously have but should not change any behavior that
matters for Terraform's purposes.
For the moment the experimental HCL2 repository is still an indirect
dependency via terraform-config-inspect, so it remains in our go.sum and
vendor directories for the moment. Because terraform-config-inspect uses
a much smaller subset of the HCL2 functionality, this does still manage
to prune the vendor directory a little. A subsequent release of
terraform-config-inspect should allow us to completely remove that old
repository in a future commit.
For users who in previous versions have relied on our lack of checking for
whether variables are declared, they may previously have seen an
overwhelming number of warnings when running Terraform v0.12.
Here we cap that number at three specific warnings and then one general
warning, so we can still give a specific source location for the first
couple (for users who have genuinely made a typo) but summarize away a
large number for those who are seeing this because they've not yet
migrated to using environment variables.
In Terraform 0.11 and earlier we just silently ignored undeclared
variables in -var-file and the automatically-loaded .tfvars files. This
was a bad user experience for anyone who made a typo in a variable name
and got no feedback about it, so we made this an error for 0.12.
However, several users are now relying on the silent-ignore behavior for
automation scenarios where they pass the same .tfvars file to all
configurations in their organization and expect Terraform to ignore any
settings that are not relevant to a specific configuration. We never
intentionally supported that, but we don't want to immediately break that
workflow during 0.12 upgrade.
As a compromise, then, we'll make this a warning for v0.12.0 that contains
a deprecation notice suggesting to move to using environment variables
for this "cross-configuration variables" use-case. We don't produce errors
for undeclared variables in environment variables, even though that
potentially causes the same UX annoyance as ignoring them in vars files,
because environment variables are assumed to live in the user's session
and this it would be very inconvenient to have to unset such variables
when moving between directories. Their "ambientness" makes them a better
fit for these automatically-assigned general variable values that may or
may not be used by a particular configuration.
This can revert to being an error in a future major release, after users
have had the opportunity to migrate their automation solutions over to
use environment variables.
We don't seem to have any tests covering this specific situation right
now. That isn't ideal, but this change is so straightforward that it would
be relatively expensive to build new targeted test cases for it and so
I instead just hand-tested that it is indeed now producing a warning where
we were previously producing an error. Hopefully if there is any more
substantial work done on this codepath in future that will be our prompt
to add some unit tests for this.
This new source type should be used for variables loaded from .tfvars files that were explicitly passed as command line arguments (e.g. -var-file=foo.tfvars)
Due to how deeply the configuration types go into Terraform Core, there
isn't a great way to switch out to HCL2 gradually. As a consequence, this
huge commit gets us from the old state to a _compilable_ new state, but
does not yet attempt to fix any tests and has a number of known missing
parts and bugs. We will continue to iterate on this in forthcoming
commits, heading back towards passing tests and making Terraform
fully-functional again.
The three main goals here are:
- Use the configuration models from the "configs" package instead of the
older models in the "config" package, which is now deprecated and
preserved only to help us write our migration tool.
- Do expression inspection and evaluation using the functionality of the
new "lang" package, instead of the Interpolator type and related
functionality in the main "terraform" package.
- Represent addresses of various objects using types in the addrs package,
rather than hand-constructed strings. This is not critical to support
the above, but was a big help during the implementation of these other
points since it made it much more explicit what kind of address is
expected in each context.
Since our new packages are built to accommodate some future planned
features that are not yet implemented (e.g. the "for_each" argument on
resources, "count"/"for_each" on modules), and since there's still a fair
amount of functionality still using old-style APIs, there is a moderate
amount of shimming here to connect new assumptions with old, hopefully in
a way that makes it easier to find and eliminate these shims later.
I apologize in advance to the person who inevitably just found this huge
commit while spelunking through the commit history.
Keith Kirk