This includes the fix for a bug in what Terraform calls the "yamldecode"
function, where it was not correctly handling any situation where the
decode result is a null value. It was previously returning an unknown
value in that case, whereas now it returns a null value as expected.

* Convert variable types before applying defaults

* revert change to unrelated test

* Add another test case to verify behaviour

* update go-cty

* Update internal/terraform/eval_variable.go
Co-authored-by: alisdair <alisdair@users.noreply.github.com>
Co-authored-by: alisdair <alisdair@users.noreply.github.com>

* Update go-cty to latest version

* go mod tidy

Added support for generic OIDC authentication (eg. Gitlab) and ensure documentation is more clear about it´s usage. oidc_request_url and oidc_request_token are meant to be used for Github Actions only.

* Add ability to use customer-managed KMS key to encrypt state, add acceptance tests

* Change test names for different encrpytion methods

* Commit files updated by `go mod tidy`

* Add guard against missing ENVs to `setupKmsKey` func

* Update KMS setup function to get credentials from ENVs

* Update tests to not include zero-values in config

This means that default values are supplied later by TF instead of supplied as config from the user

This also avoids issues related to making field conflicts explicit with `ConflictsWith`

* Make `encryption_key` & `kms_encryption_key` conflicting fields

Removing the Default from `encryption_key` does not appear to be a breaking change when tested manually

* Add ability to set `kms_encryption_key` via ENV

* Refactor `encryption_key` to use `DefaultFunc` to access ENV, if set

* Remove comments

* Update `gcs` backend docs & descriptions in schema

* Update `gcs` backend docs to include information on encryption methods

* Apply technical writing suggestions from code review
Co-authored-by: Matthew Garrell <69917312+mgarrell777@users.noreply.github.com>

* Update documentation to remove passive voice

* Change use of context in tests, add inline comment, update logs

* Remove use of `ReadPathOrContents` for new field
Co-authored-by: Matthew Garrell <69917312+mgarrell777@users.noreply.github.com>

Also add regression test coverage of the crash. This would occur when
objects with optional attributes had default values of different type
from the attribute type, and the objects were members of a collection.

For example:

list(object({
  a = optional(set(string), [])
}))

If this type constraint is applied to a variable value where one object
has a set(string) value for a, and the other object applies the empty
tuple default, Terraform would crash.

This commit updates the go-tfe library to the latest version (1.10.0). This is needed by
later commits for the pre-apply task stage.

The 2.14.0 release of HCL includes the typeexpr changes we tested here,
so now we can revert to using the HCL package and remove our fork.

* remove deprecated backends

* remove backend docs

Remove references to deprecated backends from docs.

This fixes a possible panic in what Terraform calls the "flatten" function
in situations where a user passes in a null value of a sequence type.
The function will now treat that the same as a null value of any other
type.

* refactor: Use tfaddr for provider address parsing

* refactor: Use tfaddr for module address parsing

* deps: introduce hashicorp/terraform-registry-address

* Fail global required_version check if it contains any prerelease fields

* go mod tidy

* Improve required_version prerelease not supported error string

* Add prerelease version constraint unit tests

* Fix side-effects by populating global diags too soon

This allows us to remove the manual replace directives
github.com/dgrijalva/jwt-go and google.golang.org/grpc, so that we can
remove the CVE warnings and update the grpc packages.

While the etcdv3 backend is also marked as deprecated, the changes here
are done in a manner to keep that backend working for the time being.

This means we can now use type parameter syntax where appropriate.

This commit also includes an upgrade to the golang.org/x/tools module,
in order to get a newer version of "stringer" that supports the type
parameters syntax.

The version that was in use previously broke my runs with a nice `ssh:
handshake failed: agent unsupported algorithm "ssh-ed25519"` error.  I
took a further look into this, and saw that the change that broke ssh
for me was fixed in https://github.com/golang/crypto/commit/46612604a.
Yay!

This tagged release is a superset of the specific commit we had previously
selected, adding in just an improved error message for inconsistent result
types in a conditional expression.

This is intended to eventually replace the CircleCI-based checks we use
as part of the PR process in this repository. We're already using GitHub
Actions for various other processes in this repository, so this change is
motivated by consistency of having all of our automation running in the
same system and written in the same language.

This is not a complete replacement for our CircleCI workflow yet, and
probably won't ever be because the CircleCI workflow contains some steps
that are arguably redundant with other processes we follow elsewhere.
However, the CircleCI workflow remains for now and won't be removed until
we're satisfied that enough of it is replicated by this GitHub Actions
workflow.

Upgrade go-tfe dependency to use 1.0 version. It contains breaking changes, so we are updating method signatures, method names and the type of optional parameters, as needed. (#30626)

`go-slug` has been updated to not upload `terraform.tfstate` to the slug
so that a user will no longer receive the error message about the
leftover state file after migrating from the local backend to TFC.