Invalid Index on data lookup on multiple vault auth backend - terraform

Question

I am writing a terraform module creates a single entity with multiple aliases. I'm an unable to lookup aliases auth backend. am I missing something. Any help greatly appreciated.
data "vault_auth_backend" "b" {
provider = vault.this
for_each = {
for alias in var.entity.aliases :
alias.type => alias
}
path = each.value.auth_path
}
resource "vault_identity_entity_alias" "alias" {
provider = vault.this
for_each = {
for alias in var.entity.aliases :
alias.name => alias
}
name = each.key
mount_accessor = lookup(data.vault_auth_backend.b[each.key], "accessor", null)
canonical_id = vault_identity_entity.entity.id
}
Terraform Plan output:
Error: Invalid index
on .terraform/modules/vault_dba_entity/main.tf line 31, in resource "vault_identity_entity_alias" "alias":
31: mount_accessor = lookup(data.vault_auth_backend.b[each.key], "accessor", null)
|----------------
| data.vault_auth_backend.b is object with 2 attributes
| each.key is "ldap-team-foo"
The given key does not identify an element in this collection value.
Error: Invalid index
on .terraform/modules/vault_dba_entity/main.tf line 31, in resource "vault_identity_entity_alias" "alias":
31: mount_accessor = lookup(data.vault_auth_backend.b[each.key], "accessor", null)
|----------------
| data.vault_auth_backend.b is object with 2 attributes
| each.key is "aws-team-foo"

Answer 1

Your for_each blocks are not the same: in the vault_auth_backend you are using the type of the alias as the key, while in the vault_identity_entity_alias you are using its name. Then you try to look up in the vault_auth_backend using the name, which won't work because that uses type for its key.
Change the vault_auth_backend to use alias.name => alias instead of alias.type => alias.