Prior to Terraform 0.12 these two functions were the only way to construct
literal lists and maps (respectively) in HIL expressions. Terraform 0.12,
by switching to HCL 2, introduced first-class syntax for constructing
tuple and object values, which can then be converted into list and map
values using the tolist and tomap type conversion functions.
We marked both of these functions as deprecated in the Terraform v0.12
release and have since then mentioned in the docs that they will be
removed in a future Terraform version. The "terraform 0.12upgrade" tool
from Terraform v0.12 also included a rule to automatically rewrite uses
of these functions into equivalent new syntax.
The main motivation for removing these now is just to get this change made
prior to Terraform 1.0. as we'll be doing with various other deprecations.
However, a specific reason for these two functions in particular is that
their existence is what caused us to invent the idea of a "type expression"
as a distinct kind of expression in Terraform v0.12, and so removing them
now would allow potentially unifying type expressions with value
expressions in a future release.
We do not have any current specific plans to make that change, but one
potential motivation for doing so would be to take another attempt at a
generalized "convert" function which takes a type as one of its arguments.
Our previous attempt to implement such a function was foiled by the fact
that Terraform's expression validator doesn't have any way to know to
treat one argument of a particular function as special, and so it was
generating incorrect error messages. We won't necessarily do that, but
having these "list" and "map" functions out of the way leaves the option
open.
This is an analog to the "alltrue" function, using OR as the reduce
operator rather than AND.
This also includes some simplification of the "alltrue" implementation
to implement it similarly as a sort of reduce operation with AND
as the reduce operator, but with the same effective behavior.
Fix for issue #26320 - this allows us to derive known values from
partially known maps where we can, and may prevent unnecessary
destroy/rebuild cycles during apply in some cases.
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."
}
}
```
The map function assumed that the key arguments were strings, and would
panic if they were not.
After this commit, calling `map(1, 2)` will result in a map `{"1" = 1}`,
and calling `map(null, 1)` will result in a syntax error.
Fixes#23346, fixes#23043
This PR implements 2 changes to the merge function.
- Rather than always defining the merge return type as dynamic, return
a precise type when all argument types match, or all possible object
attributes are known.
- Always return a value containing all keys when the keys are known.
This allows the use of merge output in for_each, even when keys are yet
to be determined.
* lang/funcs: lookup() can work with maps of lists, maps and objects
lookup() can already handle aribtrary objects of (whatever) and should
handle maps of (whatever) similarly.
The function would previously panic when one or more null values were among the arguments.
The new behavior treats nulls as empty strings, therefore, it removes them.
Added higher-level test for matchkeys to exercise mixing
types in searchset. This had to be in the functions tests so the HCL
auto conversion from tuple to list would occur.
`matchkeys` was returning a (false) error if the searchset was a
variable, since then the type of the keylist and searchset parameters
would not match.
This does slightly change the behavior: previously matchkeys would
produce an error if the parameters were not of the same type, for e.g.
if searchset was a list of strings and keylist was a list of integers.
This no longer produces an error.
Previously the type-selection codepath for an input tuple referred
unconditionally to the start and end index values. In the Type callback,
only the types of the arguments are guaranteed to be known, so any access
to the values must be guarded with an .IsKnown check, or else the function
will not short-circuit properly when an unknown value is passed.
Now we will check the start and end indices are in range when we have
enough information to do so, but we'll return an approximate result if
either is unknown.
FlattenFunc can return lists and tuples when individual elements are
unknown. Only return an unknown tuple if the number of elements cannot
be determined because it contains an unknown series.
Make sure flatten can handle non-series elements, which were previously
lost due to passing a slice value as the argument.
When slicing a list containing unknown values, the list itself is known,
and slice should return the proper slice of that list.
Make SliceFunc return the correct type for slices of tuples, and
disallow slicing sets.
cty now guarantees that sets of primitive values will iterate in a
reasonable order. Previously it was the caller's responsibility to deal
with that, but we invariably neglected to do so, causing inconsistent
ordering. Since cty prioritizes consistent behavior over performance, it
now imposes its own sort on set elements as part of iterating over them so
that calling applications don't have to worry so much about it.
This change also causes cty to consistently push unknown and null values
in sets to the end of iteration, where before that was undefined. This
means that our diff output will now consistently list additions before
removals when showing sets, rather than the ordering being undefined as
before.
The ordering of known, non-null, non-primitive values is still not
contractually fixed but remains consistent for a particular version of
cty.
* 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
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.
Now that our language supports tuple/object types in addition to list/map
types, it's convenient for zipmap to be able to produce an object type
given a tuple, since this makes it symmetrical with "keys" and "values"
such the the following identity holds for any map or object value "a"
a == zipmap(keys(a), values(a))
When the values sequence is a tuple, the result has an object type whose
attribute types correspond to the given tuple types.
Since an object type has attribute names as part of its definition, there
is the additional constraint here that the result has an unknown type
(represented by the dynamic pseudo-type) if the given values is a tuple
and the given keys contains any unknown values. This isn't true for values
as a list because we can predict the resulting map element type using
just the list element type.
The "values" function wasn't producing consistently-ordered keys in its
result, leading to crashes. This fixes#19204.
While working on these functions anyway, this also improves slightly their
precision when working with object types, where we can produce a more
complete result for unknown values because the attribute names are part
of the type. We can also produce results for known maps that have unknown
elements; these unknowns will also appear in the values(...) result,
allowing them to propagate through expressions.
Finally, this adds a few more test cases to try different permutations
of empty and unknown values.
When the value we're looking in has an object type, we need to know the
key in order to decide the result type. Therefore an object lookup with
an unknown key must produce cty.DynamicVal, not an unknown value with a
known type.
Since we need to know the index to know the result type for a tuple, we
need a special case here to deal with that situation and return
cty.DynamicVal; we can't predict the result type exactly until we know the
element type.
Martin Atkins