How to call a value in map element only when it matches another var - foreach

Question

I am using the Terraform provider mrparkers/keycloak to attempt to assign Keycloak groups a list of users.
The snippet below creates realms, groups, and users correctly, but I am stumped on the final line for calling a list of users which should belong to the group being looped through.
Anything to point me in the right direction would be hugely appreciated. :)
vars
variable "realms" {
description = "realms"
type = set(string)
default = ["mrpc"]
}
variable "mrpc-groups" {
type = map(object({
name = string
realm = string
members = set(string)
}))
default = {
"0" = {
realm = "mrpc"
name = "mrpc-admins"
members = ["hellfire", "hellfire2"]
},
"1" = {
realm = "mrpc"
name = "mrpc-mods"
members = ["hellfire2"]
}
}
}
variable "mrpc-users" {
type = map(object({
username = string
email = string
first_name = string
last_name = string
realm = string
}))
default = {
"0" = {
realm = "mrpc"
username = "hellfire"
email = "bla#bla.bla"
first_name = "hell"
last_name = "fire"
}
"1" = {
realm = "mrpc"
username = "hellfire2"
email = "bla2#bla.bla"
first_name = "hell2"
last_name = "fire2"
}
}
}
resources
resource "keycloak_realm" "realm" {
for_each = var.realms
realm = each.value
}
resource "keycloak_group" "group" {
for_each = var.mrpc-groups
realm_id = each.value["realm"]
name = each.value["name"]
depends_on = [keycloak_realm.realm]
}
resource "keycloak_user" "user" {
for_each = var.mrpc-users
realm_id = each.value["realm"]
username = each.value["username"]
email = each.value["email"]
first_name = each.value["first_name"]
last_name = each.value["last_name"]
}
resource "keycloak_group_memberships" "group_members" {
for_each = keycloak_group.group
realm_id = each.value["realm_id"]
group_id = each.value["name"]
members = [ "hellfire2" ]
# i want this to be var.mrpc-groups.*.members (* used incorrectly here i think)
# if
# var.mrpc-groups.*.name == each.value["name"]
#
# so that the correct member list in the vars is used when the matching group is being looped over
# any method to get the final outcome is good :)
}

Answer 1

We can use the distinct and flatten functions in conjunction with a for expression within a list constructor to solve this:
distinct(flatten([for key, attrs in var.mrpc_groups : attrs.members]))
As tested locally, this will return the following for your values exactly as requested in the question indicated by var.mrpc-groups.*.members:
members = [
"hellfire",
"hellfire2",
]
The for expression iterates through the variable mrpc_groups map and returns the list(string) value assigned to the members key within each group's key value pairs. The lambda/closure scope variables are simply key and attrs because the context is unclear to me, so I was unsure what a more descriptive name would be.
The returned structure would be a list where each element would be the list assigned to the members key (i.e. [["hellfire", "hellfire2"], ["hellfire2"]]). We use flatten to flatten the list of lists into a single list comprised of the elements of each nested list.
There would still be duplicates in this flattened list, and therefore we use the distinct function to return a list comprised of only unique elements.
For the additional question about assigning the members associated with the group at the current iteration, we can simply implement the following:
members = flatten([for key, attrs in var.mrpc_groups : attrs.members if attrs.name == each.value["name"]])
This will similarly iterate through the map variable of var.mrpc_groups, and construct a list of the members list filtered to only the group matching the name of the current group iterated through keycloak_group.group. We then flatten again because it is also a nested list similar to the first question and answer.
Note that for this additional question it would be easier for you in general and for this answer if you restructured the variable keys to be the name of the group instead of as a nested key value pair.