* Introduce "Local" terminology for non-absolute provider config addresses
In a future change AbsProviderConfig and LocalProviderConfig are going to
become two entirely distinct types, rather than Abs embedding Local as
written here. This naming change is in preparation for that subsequent
work, which will also include introducing a new "ProviderConfig" type
that is an interface that AbsProviderConfig and LocalProviderConfig both
implement.
This is intended to be largely just a naming change to get started, so
we can deal with all of the messy renaming. However, this did also require
a slight change in modeling where the Resource.DefaultProviderConfig
method has become Resource.DefaultProvider returning a Provider address
directly, because this method doesn't have enough information to construct
a true and accurate LocalProviderConfig -- it would need to refer to the
configuration to know what this module is calling the provider it has
selected.
In order to leave a trail to follow for subsequent work, all of the
changes here are intended to ensure that remaining work will become
obvious via compile-time errors when all of the following changes happen:
- The concept of "legacy" provider addresses is removed from the addrs
package, including removing addrs.NewLegacyProvider and
addrs.Provider.LegacyString.
- addrs.AbsProviderConfig stops having addrs.LocalProviderConfig embedded
in it and has an addrs.Provider and a string alias directly instead.
- The provider-schema-handling parts of Terraform core are updated to
work with addrs.Provider to identify providers, rather than legacy
strings.
In particular, there are still several codepaths here making legacy
provider address assumptions (in order to limit the scope of this change)
but I've made sure each one is doing something that relies on at least
one of the above changes not having been made yet.
* addrs: ProviderConfig interface
In a (very) few special situations in the main "terraform" package we need
to make runtime decisions about whether a provider config is absolute
or local.
We currently do that by exploiting the fact that AbsProviderConfig has
LocalProviderConfig nested inside of it and so in the local case we can
just ignore the wrapping AbsProviderConfig and use the embedded value.
In a future change we'll be moving away from that embedding and making
these two types distinct in order to represent that mapping between them
requires consulting a lookup table in the configuration, and so here we
introduce a new interface type ProviderConfig that can represent either
AbsProviderConfig or LocalProviderConfig decided dynamically at runtime.
This also includes the Config.ResolveAbsProviderAddr method that will
eventually be responsible for that local-to-absolute translation, so
that callers with access to the configuration can normalize to an
addrs.AbsProviderConfig given a non-nil addrs.ProviderConfig. That's
currently unused because existing callers are still relying on the
simplistic structural transform, but we'll switch them over in a later
commit.
* rename LocalType to LocalName
Co-authored-by: Kristin Laemmert <mildwonkey@users.noreply.github.com>
The existing "type" argument allows specifying a type constraint that
allows for some basic validation, but often there are more constraints on
a variable value than just its type.
This new feature (requiring an experiment opt-in for now, while we refine
it) allows specifying arbitrary validation rules for any variable which
can then cause custom error messages to be returned when a caller provides
an inappropriate value.
variable "example" {
validation {
condition = var.example != "nope"
error_message = "Example value must not be \"nope\"."
}
}
The core parts of this are designed to do as little new work as possible
when no validations are specified, and thus the main new checking codepath
here can therefore only run when the experiment is enabled in order to
permit having validations.
Traditionally we've preferred to release new language features in major
releases only, because we can then use the beta cycle to gather feedback
on the feature and learn about any usability challenges or other
situations we didn't consider during our design in time to make those
changes before inclusion in a stable release.
This "experiments" feature is intended to decouple the feedback cycle for
new features from the major release rhythm, and thus allow us to release
new features in minor releases by first releasing them as experimental for
a minor release or two, adjust for any feedback gathered during that
period, and then finally remove the experiment gate and enable the feature
for everyone.
The intended model here is that anything behind an experiment gate is
subject to breaking changes even in patch releases, and so any module
using these experimental features will be broken by a future Terraform
upgrade.
The behavior implemented here is:
- Recognize a new "experiments" setting in the "terraform" block which
allows module authors to explicitly opt in to experimental features.
terraform {
experiments = [resource_for_each]
}
- Generate a warning whenever loading a module that has experiments
enabled, to avoid accidentally depending on experimental features and
thus risking unexpected breakage on next Terraform upgrade.
- We check the enabled experiments against the configuration at module
load time, which means that experiments are scoped to a particular
module. Enabling an experiment in one module does not automatically
enable it in any other module.
This experiments mechanism is itself an experiment, and so I'd like to
use the resource for_each feature to trial it. Because any configuration
using experiments is subject to breaking changes, we are free to adjust
this experiments feature in future releases as we see fit, but once
for_each is shipped without an experiment gate we'll be blocked from
making significant changes to it until the next major release at least.
Add deprecation warning for references from destroy provisioners or
their connections to external resources or values. In order to ensure
resource destruction can be completed correctly, destroy nodes must be
able to evaluate with only their instance state.
We have sufficient information to validate destroy-time provisioners
early on during the config loading process. Later on these can be
converted to hard errors, and only allow self, count.index, and each.key
in destroy provisioners. Limited the provisioner and block evaluation
scope later on is tricky, but if the references can never be loaded,
then they will never be encountered during evaluation.
Following on from de652e22a26b, this introduces deprecation warnings for
when an attribute value expression is a template with only a single
interpolation sequence, and for variable type constraints given in quotes.
As with the previous commit, we allowed these deprecated forms with no
warning for a few releases after v0.12.0 to ensure that folks who need to
write cross-compatible modules for a while during upgrading would be able
to do so, but we're now marking these as explicitly deprecated to guide
users towards the new idiomatic forms.
The "terraform 0.12upgrade" tool would've already updated configurations
to not hit these warnings for those who had pre-existing configurations
written for Terraform 0.11.
The main target audience for these warnings are newcomers to Terraform who
are learning from existing examples already published in various spots on
the wider internet that may be showing older Terraform syntax, since those
folks will not be running their configurations through the upgrade tool.
These warnings will hopefully guide them towards modern Terraform usage
during their initial experimentation, and thus reduce the chances of
inadvertently adopting the less-readable legacy usage patterns in
greenfield projects.
Terraform 0.12.0 removed the need for putting references and keywords
in quotes, but we disabled the deprecation warnings for the initial
release in order to avoid creating noise for folks who were intentionally
attempting to maintain modules that were cross-compatible with both
Terraform 0.11 and Terraform 0.12.
However, with Terraform 0.12 now more widely used, the lack of these
warnings seems to be causing newcomers to copy the quoted versions from
existing examples on the internet, which is perpetuating the old and
confusing quoted form in newer configurations.
In preparation for phasing out these deprecated forms altogether in a
future major release, and for the shorter-term benefit of giving better
feedback to newcomers when they are learning from outdated examples, we'll
now re-enable those deprecation warnings, and be explicit that the old
forms are intended for removal in a future release.
In order to properly test this, we establish a new set of test
configurations that explicitly mark which warnings they are expecting and
verify that they do indeed produce those expected warnings. We also
verify that the "success" tests do _not_ produce warnings, while removing
the ones that were previously written to succeed but have their warnings
ignored.
This also fixes a few things with resource for_each:
It makes validation more like validation for count.
It makes sure the index is stored in the state properly.
When loading nested modules, the child module diagnostics were dropped
in the recursive function. This mean that the config from the submodules
wasn't fully loaded, even though no errors were reported to the user.
This caused further problems if the plan was stored in a plan file, when
means only the partial configuration was stored for the subsequent apply
operation, which would result in unexplained "Resource node has no
configuration attached" errors later on.
Also due to the child module diagnostics being lost, any newly added
nested modules would be silently ignored until `init` was run again
manually.
Martin Atkins