A very common question since we launched the two repetition constructs
is how to deal with situations where the input data structure doesn't
match one-to-one with the desired configuration.
This adds some full worked examples of two common situations that have
come up in questions. To avoid adding a lot of extra content to the
already-large "expressions" and "resources" pages, the main bulk of this
new content lives with the relevant functions themselves as a full example
of one thing they are good for, and then we'll link to them from the two
general documentation sections where folks are likely to be reading when
they encounter the problem.
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.
The cidrsubnets function signature is intentionally very low-level and
focused on the core requirement of generating addresses. This registry
module then wraps it with some additional functionality to make it more
convenient to generate and use subnet address ranges.
This is a companion to cidrsubnet that allows bulk-allocation of multiple
subnet addresses at once, with automatic numbering.
Unlike cidrsubnet, cidrsubnets allows each of the allocations to have a
different prefix length, and will pack the networks consecutively into the
given address space. cidrsubnets can potentially create more complicated
addressing schemes than cidrsubnet alone can, because it's able to take
into account the full set of requested prefix lengths rather than just
one at a time.
* website/formatdate: update example
The given example was showing HOUR:MONTH instead of HOUR:MINUTE
Fixes#22598
* website/import: remove reference to no-longer-working option
Users can no longer supply `-config=""` to tell Terraform not to load
configuration for import.
Fixes#22294
* website/provisioners: `host` is required in connection blocks
Fixes#21877
* website/variables: clarify variable definition precedence
It was not entirely obvious that a variable could not be assigned
multiples times in a single source.
Fixes#21682
* website/backend/local: add `workspace_dir` attribute
Fixes#21391
* website/output: `sensitive` outputs are redacted in output
Fixes#21502
* website/backends: sidebar order tweak
It makes sense for backend 'configuration' to appear before 'init'.
Fixes#13796
* Revert "website/formatdate: update example"
This reverts commit ccd93c86ddd15a21625c0767702ee1cc62e77254.
Reference: https://github.com/hashicorp/terraform/issues/16697
Enumerates a set of regular file names from a given glob pattern. Implemented via the Go stdlib `path/filepath.Glob()` functionality. Notably, stdlib does not support `**` or `{}` extended patterns. See also: https://github.com/golang/go/issues/11862
To support the extended glob patterns, it will require adding a dependency on a third party library or adding our own matching code.
The Terraform Enterprise brand has now been split into two parts:
- Terraform Cloud is the application that helps teams use Terraform together,
with remote state storage, a shared run environment, etc.
- Terraform Enterprise is the on-premise distribution that lets enterprises run
a private instance of the Terraform Cloud application.
The former TFE docs have been split accordingly.
- Make these descriptions more similar, since they do basically the same thing.
- Add some subheaders to break up the wall of text and make it more skimmable.
- Nudge people more firmly toward `for_each` if they need to actually
incorporate data from a variable into their instances.
- Add version note so you know whether you can use this yet.
These existing upstream cty functions allow matching strings against
regular expression patterns, which can be useful if you need to consume
a non-standard string format that Terraform doesn't (and can't) have a
built-in function for.
We added the csvdecode function originally with the intent of it being
used with for_each, but because csvdecode was released first we had a
section in its documentation warning about the downsides of using it with
"count", since that seemed like something people would be likely to try.
With resource "for_each" now merged, we can replace that scary section
with a more positive example of using these two features together.
We still include a paragraph noting that "count" _could_ be used here, but
with a caution against doing so. This is in the hope of helping users
understand the difference between these two patterns and why for_each is
the superior choice for most situations.
The search "terraform leading zero" does not find the `format()`
function, which is perfectly capable of adding leading zeros.
Thus I have added this one word to help people find `format()`.
This also includes a previously-missing test that verifies the behavior
described here, implemented as a planning context test for consistency
with how the other ignore_changes tests are handled.
There have been a few questions about this so far which indicated that the
previous docs for this feature were very lacking. This is an attempt to
describe more completely what "any" means, and in particular that it isn't
actually a type at all but rather a placeholder for a type to be selected
dynamically.
Based on some common questions and feedback since the v0.12.0 release,
here we add some small additional content to the documentation for
"dynamic" blocks, covering how to access the keys of the collection being
iterated over and how to fold multiple collections into a single one to
achieve the effect of a nested iteration.
These follow the same principle as jsondecode and jsonencode, but use
YAML instead of JSON.
YAML has a much more complex information model than JSON, so we can only
support a subset of it during decoding, but hopefully the subset supported
here is a useful one.
Because there are many different ways to _generate_ YAML, the yamlencode
function is forced to make some decisions, and those decisions are likely
to affect compatibility with other real-world YAML parsers. Although the
format here is intended to be generic and compatible, we may find that
there are problems with it that'll we'll want to adjust for in a future
release, so yamlencode is therefore marked as experimental for now until
the underlying library is ready to commit to ongoing byte-for-byte
compatibility in serialization.
The main use-case here is met by yamldecode, which will allow reading in
files written in YAML format by humans for use in Terraform modules, in
situations where a higher-level input format than direct Terraform
language declarations is helpful.
This is similar to the function of the same name in Python, generating a
sequence of numbers as a list that can then be used in other
sequence-oriented operations.
The primary use-case for it is to turn a count expressed as a number into
a list of that length, which can then be iterated over or passed to a
collection function to produce that number of something else, as shown
in the example at the end of its documentation page.
- Note that we intentionally omitted it from the sidebar, to reduce confusion.
- Write a summary up top so you can stop reading sooner if you don't actually need this.
* lang/funcs: testing of functions through the lang package API
The function-specific unit tests do not cover the HCL conversion that happens when the functions are called in a terraform configuration. For e.g., HCL converts sets to lists before passing it to the function. This means that we could not test passing a set in the function _unit_ tests.
This adds a higher-level acceptance test, plus a check that every (pure) function has a test.
* website/docs: update function documentation
There was some leftover v0.11-style interpolation syntax here.
We prefer to use a "naked" expression in situations like this where the result
isn't a string, because interpolations returning non-strings is a common source
of confusion for new users.
* funcs/coalesce: return the first non-null, non-empty element from a
sequence.
The go-cty coalesce function, which was originally used here, returns the
first non-null element from a sequence. Terraform 0.11's coalesce,
however, returns the first non-empty string from a list of strings.
This new coalesce function aims to preserve terraform's documented
functionality while adding support for additional argument types. The
tests include those in go-cty and adapted tests from the 0.11 version of
coalesce.
* website/docs: update coalesce function document
The re-introduction of some of the ambiguity between argument and nested
block syntax (for compatibility with existing provider patterns)
unfortunately leads to some interesting consequences for attributes using
this mode.
While the behavior is generally as before in straightforward cases, this
page aims to spell out some of the different usage patterns explicitly
for the benefit of those writing more complex configurations, such as
generic re-usable modules where using argument vs. block syntax leads to
some real differences.
This page is intentionally not linked from anywhere in the part of the
website maintained in the Terraform repository. Instead, it can be linked
from the provider documentation for any argument where this pattern is
used, to help users understand the ways in which that argument might
deviate from the usual behaviors of arguments vs. nested blocks.
Some users are not accustomed to thinking of IP addresses in a bitwise
fashion, so the hope here is to give enough of an introduction to that way
of thinking for the reader to understand what the "newbits" and "netnum"
arguments represent.
For 0.11 I just specified the naming rules; for 0.12, I added some info about
referencing values and tightened up the layout of the optional arguments.
This commit also syncs up descriptions of `depends_on`.
As part of this, I'm copying the entire text of the 0.12
docs/configuration/modules.html page into docs/configuration-0-11/modules.html —
some of the 0.11 pages needed to be able to link to the moved content, I
didn't want to jump versions jarringly, and a close reading didn't reveal
anything in there that's inaccurate for 0.11.
The "terraform fmt" command produces a different canonical form than we
were showing in our examples here. Our examples should always reflect the
conventions applied by "terraform fmt" to avoid confusion.
(This particular decision is a pragmatic one because the formatter design
needs to use the same rules for the colon in the ? : conditional operator
as for the colon in "for" expressions.)
Since references to attributes of resources are by far the most common
reference type, and the mapping of resource type config to the attributes
is not always obvious, here we give some real examples of patterns for
accessing different configuration constructs within resource blocks along
with the resource type's exported attributes.
Since we don't have any real examples of labelled nested blocks yet (the
current SDK doesn't support them) I've included a hypothetical example for
now just to establish the patterns around them in preparation for
beginning to introduce them as we roll out this feature in the SDK.
As well as some general consolidation and reorganizing, this also includes
some updated advice for making the best use of new Terraform v0.12
features to create infrastructure building-blocks.
In particular, the "Module Usage" documentation is now consolidated into
the configuration section in order to bring all of our general language
documentation together, and the top-level "Modules" section is now
primarily focused on module _authors_ as an audience, covering topics such
as publishing modules and designing them for reuse.
* docs: update plan command documentation. Fixes#19235
* docs: added a missing reserved variable name. Fixes#19159.
* website: add note that resource names cannot start with a number
* website: add some notes to the 0.12 upgrade guide
In prior versions, we recommended using hash functions in conjunction with
the file function as an idiom for detecting changes to upstream blobs
without fetching and comparing the whole blob.
That approach relied on us being able to return raw binary data from
file(...). Since Terraform strings pass through intermediate
representations that are not binary-safe (e.g. the JSON state), there was
a risk of string corruption in prior versions which we have avoided for
0.12 by requiring that file(...) be used only with UTF-8 text files.
The specific case of returning a string and immediately passing it into
another function was not actually subject to that corruption risk, since
the HIL interpreter would just pass the string through verbatim, but this
is still now forbidden as a result of the stricter handling of file(...).
To avoid breaking these use-cases, here we introduce variants of the hash
functions a with "file" prefix that take a filename for a disk file to
hash rather than hashing the given string directly. The configuration
upgrade tool also now includes a rule to detect the documented idiom and
rewrite it into a single function call for one of these new functions.
This does cause a bit of function sprawl, but that seems preferable to
introducing more complex rules for when file(...) can and cannot read
binary files, making the behavior of these various functions easier to
understand in isolation.
It's not normally necessary to make explicit type conversions in Terraform
because the language implicitly converts as necessary, but explicit
conversions are useful in a few specialized cases:
- When defining output values for a reusable module, it may be desirable
to force a "cleaner" output type than would naturally arise from a
computation, such as forcing a string containing digits into a number.
- Our 0.12upgrade mechanism will use some of these to replace use of the
undocumented, hidden type conversion functions in HIL, and force
particular type interpretations in some tricky cases.
- We've found that type conversion functions can be useful as _temporary_
workarounds for bugs in Terraform and in providers where implicit type
conversion isn't working correctly or a type constraint isn't specified
precisely enough for the automatic conversion behavior.
These all follow the same convention of being named "to" followed by a
short type name. Since we've had a long-standing convention of running all
the words together in lowercase in function names, we stick to that here
even though some of these names are quite strange, because these should
be rarely-used functions anyway.
Graham Davison