Terraform v0.10 introduced .terraform/plugins as a cache directory for
automatically-installed plugins, Terraform v0.13 later reorganized the
directory structure inside but retained its purpose as a cache.
The local cache used to also serve as a record of specifically which
packages were selected in a particular working directory, with the intent
that a second run of "terraform init" would always select the same
packages again. That meant that in some sense it behaved a bit like a
local filesystem mirror directory, even though that wasn't its intended
purpose.
Due to some unfortunate miscommunications, somewhere a long the line we
published some documentation that _recommended_ using the cache directory
as if it were a filesystem mirror directory when working with Terraform
Cloud. That was really only working as an accident of implementation
details, and Terraform v0.14 is now going to break that because the source
of record for the currently-selected provider versions is now the
public-facing dependency lock file rather than the contents of an existing
local cache directory on disk.
After some consideration of how to move forward here, this commit
implements a compromise that tries to avoid silently doing anything
surprising while still giving useful guidance to folks who were previously
using the unsupported strategy. Specifically:
- The local cache directory will now be .terraform/providers rather than
.terraform/plugins, because .terraform/plugins is effectively "poisoned"
by the incorrect usage that we can't reliably distinguish from prior
version correct usage.
- The .terraform/plugins directory is now the "legacy cache directory". It
is intentionally _not_ now a filesystem mirror directory, because that
would risk incorrectly interpreting providers automatically installed
by Terraform v0.13 as if they were a local mirror, and thus upgrades
and checksum fetches from the origin registry would be blocked.
- Because of the previous two points, someone who _was_ trying to use the
legacy cache directory as a filesystem mirror would see installation
fail for any providers they manually added to the legacy directory.
To avoid leaving that user stumped as to what went wrong, there's a
heuristic for the case where a non-official provider fails installation
and yet we can see it in the legacy cache directory. If that heuristic
matches then we'll produce a warning message hinting to move the
provider under the terraform.d/plugins directory, which is a _correct_
location for "bundled" provider plugins that belong only to a single
configuration (as opposed to being installed globally on a system).
This does unfortunately mean that anyone who was following the
incorrectly-documented pattern will now encounter an error (and the
aforementioned warning hint) after upgrading to Terraform v0.14. This
seems like the safest compromise because Terraform can't automatically
infer the intent of files it finds in .terraform/plugins in order to
decide automatically how best to handle them.
The internals of the .terraform directory are always considered
implementation detail for a particular Terraform version and so switching
to a new directory for the _actual_ cache directory fits within our usual
set of guarantees, though it's definitely non-ideal in isolation but okay
when taken in the broader context of this problem, where the alternative
would be silent misbehavior when upgrading.
The upgrade requirements for this release are considerably more modest
than for Terraform v0.13, so this time we just have some notes about a
few changes in behavior that may be impactful to some users.
This first pass is intended to be included as part of a forthcoming beta
testers' guide as we begin the v0.14 beta testing period. We will make
further changes to this upgrade guide based on feedback from those who
participate in the beta process.
Note that this upgrade guide is not intended as release marketing material
and so its presentation is focused on addressing concerns users might
encounter while upgrading. We'll share highlights from the release in
other contexts, such as the changelog and in the product blog.
This builds on an experimental feature in the underlying cty library which
allows marking specific attribtues of an object type constraint as
optional, which in turn modifies how the cty conversion package handles
missing attributes in a source value: it will silently substitute a null
value of the appropriate type rather than returning an error.
In order to implement the experiment this commit temporarily forks the
HCL typeexpr extension package into a local internal/typeexpr package,
where I've extended the type constraint syntax to allow annotating object
type attributes as being optional using the HCL function call syntax.
If the experiment is successful -- both at the Terraform layer and in
the underlying cty library -- we'll likely send these modifications to
upstream HCL so that other HCL-based languages can potentially benefit
from this new capability.
Because it's experimental, the optional attribute modifier is allowed only
with an explicit opt-in to the module_variable_optional_attrs experiment.
This includes both the main documentation about the lock file itself and
changes to related documentation about Terraform commands that interact
with the lock file.
We will likely continue to update this first pass of documentation as we
get feedback and questions during the prerelease period.
* website: Update all Learn crosslinks
The URL structure on Learn recently changed, so it's time to update some URLs.
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>
Move the information about state from the "caveats" to the main
info section, using similar information to sensitive outputs.
Updates the header of the section from similar inspiration.
We can remove the caveat about changing map elements.
Add a little more text about the intended use case for ignore_changes,
as the common case of fixing erroneous provider behavior should not be
the primary motivation for the maintenance of this feature.
* Put link to tutorial in its own section, call it a tutorial instead of guide, and use new canonical URL.
* Mention limitations of using import with a remote backed
* Typo fix
Co-authored-by: Nick Fagerlund <nick.fagerlund@gmail.com>
This commit adds an `alltrue` function to Terraform configuration. A
reason we might want this function is because it will enable more
powerful custom variable validations. For example:
```hcl
variable "amis" {
type = list(object({
id = string
}))
validation {
condition = (alltrue([
for a in var.amis : length(a.id) > 4 && substr(a.id, 0, 4) == "ami-"
]))
error_message = "The ID of at least one AMI was invalid."
}
}
```
For a credentials helper plugin to be useful with Terraform 0.13+, we
need to cope with the case of having no credentials for a host without
this being an error. This is to allow the public Terraform Registry to
be accessed without supplying a token.
The way to implement this is to respond to queries for credentials for a
host which has no credentials stored with an empty object and a success
exit code. This contradicts the previous documentation, which calls for
an error response in this case.
* Adding not about data-sources and depends-on for 0.12 users
* Bold
* A little more markdown
* A little more markdown for data_sources in 0.12
* Some iteration based on good feedback
Tony Carmichael