In 0.12, the outputs for a data source of terraform_remote_state are
nested under the 'outputs' attribute [1]. This updates the docs
to make this change clearer.
Worked with @radeksimko at Terraform hackday, who has submitted a
related upgrade guide [2]
[1] 1f4d2f4c50/builtin/providers/terraform/data_source_state.go (L16-L43)
[2] d8e00191b7
Because of the different possibilities for arranging the nav sidebars, we want
to make sure:
- IDs for the 0.11 and 0.12 language docs have a common prefix.
- That prefix is not the exact string `docs-config`.
Have I mentioned before that I really dislike this prefix matching behavior.
This is a non-working commit, because a bunch of links (including the sidebar
nav) are broken. Using a transition commit like this makes it easier to see the
changes necessary to get this content woven into the site.
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.
The sethaselement, setintersection, and setunion functions are defined in
the cty stdlib. Making them available in Terraform will make it easier to
work with sets, and complement the currently-Terraform-specific setproduct
function.
In the long run setproduct should probably move into the cty stdlib too,
but since it was submitted as a Terraform function originally we'll leave
it here now for simplicity's sake and reorganize later.
In our new world it produces either a set of a tuple type or a list of a
tuple type, depending on the given argument types.
The resulting collection's element tuple type is decided by the element
types of the given collections, allowing type information to propagate
even if unknown values are present.
This document was previously copied to the "Extending Terraform" section (in the
terraform-website repo), and the old URL was redirected so that the copy in
/guides can no longer be reached on the website. But the old copy of the file
remained, and now it runs the risk of confusing contributors, since the copy in
terraform-website/.../docs/extend is the more up-to-date version.
Kristin Laemmert