The -var command line option comes with the disadvantage that a user must
contend both with Terraform's own parser and with the parser in whichever
shell they've decided to use, and different shells on different platforms
have different rules.
Previously we've largely just assumed that folks know the appropriate
syntax for the shell they chose, but it seems that command lines involving
spaces and other special characters arise rarely enough in other commands
that Terraform is often the first time someone needs to learn the
appropriate syntax for their shell.
We can't possibly capture all of the details of all shells in our docs,
because that's far outside of our own scope, but hopefully this new
section will go some way to give some real examples that will help folks
figure out how to write suitable escape sequences, if they choose to
set complex variable values on the command line rather than in .tfvars
as we recommend elsewhere on this page.
Seems like we lost a newline in some of the shuffling it took to get this
into the live website, and so it's formatting oddly in the rendered
website. This restores the intended formatting of this as the start of
a bullet list, rather than as a continuation of the previous paragraph.
* clarify input variables opening sentence
* adjust variables description
* claraify providers text and add learn callout
* add description to providers page
* add desscription and clarify provider configuration
* add deprecation note to versions in proivder configs
* add hands on callout and clarify next steps in intro
* link to language collection from language docs
* give more context about configurtion language up front
* clarify output top page
* reorganize for each intro to present feature before notes
* move description before link out and remove passive voice
* fix typo
* clarify purpose of plan
* move explanation before learn link and fully spell boolean
* add a syntax heading to separate intro from details
* add learn callout to module source docs
* clean up intro to provider requirements and add link
* Apply suggestions from code review
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>
* Apply suggestions from code review
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>
Our module installer has a somewhat-informal idea of a "module package",
which is some external thing we can go fetch in order to add one or more
modules to the current configuration. Our documentation doesn't talk much
about it because most users seem to have found the distinction between
external and local modules pretty intuitive without us throwing a lot of
funny terminology at them, but there are some situations where the
distinction between a module and a module package are material to the
end-user.
One such situation is when using an absolute rather than relative
filesystem path: we treat that as an external package in order to make the
resulting working directory theoretically "portable" (although users can
do various other things to defeat that), and so Terraform will copy the
directory into .terraform/modules in the same way as it would download and
extract a remote archive package or clone a git repository.
A consequence of this, though, is that any relative paths called from
inside a module loaded from an absolute path will fail if they try to
traverse upward into the parent directory, because at runtime we're
actually running from a copy of the directory that's been taking out of
its original context.
A similar sort of situation can occur in a truly remote module package if
the author accidentally writes a "../" source path that traverses up out
of the package root, and so this commit introduces a special error message
for both situations that tries to be a bit clearer about there being a
package boundary and use that to explain why installation failed.
We would ideally have made escaping local references like that illegal in
the first place, but sadly we did not and so when we rebuilt the module
installer for Terraform v0.12 we ended up keeping the previous behavior of
just trying it and letting it succeed if there happened to somehow be a
matching directory at the given path, in order to remain compatible with
situations that had worked by coincidence rather than intention. For that
same reason, I've implemented this as a replacement error message we will
return only if local module installation was going to fail anyway, and
thus it only modifies the error message for some existing error situations
rather than introducing new error situations.
This also includes some light updates to the documentation to say a little
more about how Terraform treats absolute paths, though aiming not to get
too much into the weeds about module packages since it's something that
most users can get away with never knowing.
The Git book seems to be using a different anchor format now, and so this
link was previously effectively linking to the page as a whole rather
than to the specific section we're trying to refer to.
We previously had only very short descriptions of what
-ignore-remote-version does due to having the documentation for it inline
on many different command pages and -help output.
Instead, we'll now centralize the documentation about this argument on
the remote backend page, and link to it or refer to it from all other
locations. This then allows us to spend more words on discussing what
Terraform normally does _without_ this option and warning about the
consequences of using it.
This continues earlier precedent for some local-backend-specific options
which we also don't recommend for typical use. While this does make these
options a little more "buried" than before, that feels justified given
that they are all "exceptional use only" sort of options where users ought
to learn about various caveats before using them.
While there I also took this opportunity to fix some earlier omissions
with the local-backend-specific options and a few other minor consistency
tweaks.
* Add link to Modules in Package Sub-directories
Add link to "Modules in Package Sub-directories" section at top of page
* Fix broken links
* Update aws link, fixes missing anchor linkcheck
Co-authored-by: Tu Nguyen <im2nguyen@users.noreply.github.com>
This pattern follows as a natural consequence of how for_each is defined,
but I've noticed from community forum Q&A that newcomers often don't
immediately notice the connection between what for_each expects as input
and what a for_each resource produces as a result, so my aim here is to
show a short example of that in the hope of helping folks see the link
here and get ideas on how to employ the technique in other situations.
* website: v0.15 upgrade guide for sensitive resource attributes
Our earlier draft of this guide didn't include a section about the
stabilization of the "provider_sensitive_attrs" language experiment. This
new section aims to address the situation where a module might previously
have been returning a sensitive value without having marked it as such,
and thus that module will begin returning an error after upgrading to
Terraform v0.15.
As part of that, I also reviewed the existing documentation about these
features and made some edits aiming to make these four different sections
work well together if users refer to them all at once, as they are likely
to do if they follow the new links from the upgrade guide. I aimed to
retain all of the content we had before, but some of it is now in a new
location.
In particular, I moved the discussion about the v0.14 language experiment
into the upgrade guide, because it seems like a topic only really relevant
to those upgrading from an earlier version and not something folks need to
know about if they are using Terraform for the first time in v0.15 or
later.
* minor fixups
Co-authored-by: Kristin Laemmert <mildwonkey@users.noreply.github.com>
In the Terraform language we typically use lists of zero or one values in
some sense interchangably with single values that might be null, because
various Terraform language constructs are designed to work with
collections rather than with nullable values.
In Terraform v0.12 we made the splat operator [*] have a "special power"
of concisely converting from a possibly-null single value into a
zero-or-one list as a way to make that common operation more concise.
In a sense this "one" function is the opposite operation to that special
power: it goes from a zero-or-one collection (list, set, or tuple) to a
possibly-null single value.
This is a concise alternative to the following clunky conditional
expression, with the additional benefit that the following expression is
also not viable for set values, and it also properly handles the case
where there's unexpectedly more than one value:
length(var.foo) != 0 ? var.foo[0] : null
Instead, we can write:
one(var.foo)
As with the splat operator, this is a tricky tradeoff because it could be
argued that it's not something that'd be immediately intuitive to someone
unfamiliar with Terraform. However, I think that's justified given how
often zero-or-one collections arise in typical Terraform configurations.
Unlike the splat operator, it should at least be easier to search for its
name and find its documentation the first time you see it in a
configuration.
My expectation that this will become a common pattern is also my
justification for giving it a short, concise name. Arguably it could be
better named something like "oneornull", but that's a pretty clunky name
and I'm not convinced it really adds any clarity for someone who isn't
already familiar with it.
We previously added a hint to both resource for_each and dynamic blocks
about using the "flatten" and "setproduct" situations to construct
suitable collections to repeat over.
However, we used the same text in both places which ended up stating that
dynamic blocks can only accept map or set values, which is a constraint
that applies to resource for_each (because we need to assign a unique
identifier to each instance) and not to dynamic blocks (which don't have
any uniqueness enforced by Terraform Core itself).
To remove that contradiction with the text above which talks about what
is valid here, I've just generalized this to say "collection", because
the primary point of this paragraph is the "one element per desired nested
block" part, not specifically what sort of collections are permitted in
this location. (Text further up describes the supported types.)
We have these funny extra options that date back to before Terraform even
had remote state, which we've preserved along the way by most recently
incorporating them as special-case overrides for the local backend.
The documentation we had for these has grown less accurate over time as
the details have shifted, and was in many cases missing the requisite
caveats that they are only for the local backend and that backend
configuration is the modern, preferred way to deal with the use-cases they
were intended for.
We always have a bit of a tension with this sort of legacy option because
we want to keep them documented just enough to be useful to someone who
finds an existing script/etc using them and wants to know what they do,
but not to take up so much space that they might distract users from
finding the modern alternative they should consider instead.
As a compromise in that vein here I've created a new section about these
options under the local backend documentation, which then gives us the
space to go into some detail about the various behaviors and interactions
and also to discuss their history and our recommended alternatives. I then
simplified all of the other mentions of these in command documentation
to just link to or refer to the local backend documentation. My hope then
is that folks who need to know what these do can still find the docs, but
that information can be kept out of the direct path of new users so they
can focus on learning about remote backends instead.
This is certainly not the most ideal thing ever, but it seemed like the
best compromise between the competing priorities I described above.
These aim to allow hinting to Terraform about situations where it's not
able to automatically infer value sensitivity.
"nonsensitive" is for situations where Terraform's behavior is too
conservative, such as when a new value is derived from a sensitive value
in such a way that all of the sensitive content is removed.
"sensitive", on the other hand, is for situations where Terraform can't
otherwise infer that a value is sensitive. These situations should be
pretty rare in a module that's making effective use of sensitive input
variables and output values, but the documentation shows one example of
an uncommon situation where a more direct hint via this function would
be needed.
Both of these functions are aimed at only occasional use in unusual
situations. They are here for reasons of pragmatism, not because we
expect them to be used routinely or recommend their use.
Laura Pacilio