did I do something wrong? or I found a bug? - terraform

Question

this is to prove that there might be a bug in setintersection() or keys() in terraform v1.2.1
that it treats local and var differently.
I hope someone can help to confirm, or point out if I did something wrong?
# this file is to prove that there might be a bug in setintersection() or keys() in terraform v1.2.1
# that it treats local and var differently.
# I hope someone can help to confirm, or point out if I did something wrong?
# local.regions is to serve as the setintersection control set of strings
# as the keys(s_v) has non-region-related keys
locals {
regions = ["region-1", "region-2"]
}
# local.local_obj has the exact same data structure as of var.var_obj
locals {
local_obj = {
collection_local = {
subnet_local = {
other_keys = "somthing"
region-1 = "cidr-for-region-1-for-local-obj"
# region-2 = "cidr-for-region-2-for-local-obj"
}
}
}
}
# var.var_obj is a map(map(object())) data structure, outter map is the collection of subnets,
# inner map is the subnets within a collection, object is the subnet config
variable "var_obj" {
type = map(
map (
object ({
other_keys = "whatever"
region-1 = optional(string)
region-2 = optional(string)
})
)
)
default = {
collection_var = {
subnet_var = {
other_keys = "something_else"
region-1 = "cidr-for-region-1-for-var-obj"
# region-2 = "cidr-for-region-2-for-var-obj"
}
}
}
}
# local.transform-local and local.transform-var are two transforming locals to suite subnet resource needs
locals {
transform-local = flatten([
for c_k,c_v in local.local_obj : [
for s_k, s_v in c_v : [
for rg in setintersection(local.regions, keys(s_v)) : {
name = "${rg}-${s_k}"
region = rg
ip_cidr_range = s_v[rg]
}
]
]
])
transform-var = flatten([
for c_k,c_v in var.var_obj : [
for s_k, s_v in c_v : [
for rg in setintersection(local.regions, keys(s_v)) : {
name = "${rg}-${s_k}"
region = rg
ip_cidr_range = s_v[rg]
}
]
]
])
}
# output.contrast is to show the different behavior of setintersection() and keys() on local and var
# I think it is a bug?
# as commenting out the region-2 in local and var has different behavior,
# local behaves corretly, not producing region-2 record at all,
# but var transformer produced a region-2 record without ip_cidr_range, which will break the resource code execution
output "contrast" {
value = {
transform-local = local.transform-local
transform-var = local.transform-var
}
}
if uncommenting the region-2 line, setintersection() and keys() behave exactly the same on local and var:
output:
contrast : {
transform-local : [
{
name : "region-1-subnet_local"
ip_cidr_range : "cidr-for-region-1-for-local-obj"
region : "region-1"
}
{
name : "region-2-subnet_local"
ip_cidr_range : "cidr-for-region-2-for-local-obj"
region : "region-2"
}
]
transform-var : [
{
name : "region-1-subnet_var"
ip_cidr_range : "cidr-for-region-1-for-var-obj"
region : "region-1"
}
{
name : "region-2-subnet_var"
ip_cidr_range : "cidr-for-region-2-for-var-obj"
region : "region-2"
}
]
}
but if I comment out the region-2 line (as shown in code above), transform-var output is not desirable as it produces something that will cause malfunctioning
output:
contrast : {
transform-local : [
{
name : "region-1-subnet_local"
ip_cidr_range : "cidr-for-region-1-for-local-obj"
region : "region-1"
}
]
transform-var : [
{
name : "region-1-subnet_var"
ip_cidr_range : "cidr-for-region-1-for-var-obj"
region : "region-1"
}
{
name : "region-2-subnet_var"
region : "region-2"
}
]
}