Terraform - iterate over nested map

I am trying to create IAM binding for Bigquery dataset using the resource - google_bigquery_dataset_iam_binding. The requirement is I read the parameters in this resource (dataset_id, role, members) using a variable of the following structure -

 bq_iam_role_bindings = { "member1" = { "dataset1" : ["role1","role2", "role5"], "dataset2" : ["role3","role2"], }, "member2" = { "dataset3" : ["role1","role4"], "dataset2" : ["role5"], } } 

So, I need to loop over this variable and get the roles assigned on a dataset for each member. Here total resources created would be eight (for each member, each dataset and each role). I am new to terraform and understand only how to apply simple for loop over a map and for_each loop in a resource. Want to understand how is it possible what I am trying to do.

This is the nearest what I have found - Map within a map in terraform variables where I can read the value in a nested map but I need to extract key also in my case. Can anyone help here please.

1 Answer

You could re-organize it into more for_each friendly list of objects and store it in a local helper_list.

For example:

variable "bq_iam_role_bindings" { default = { "member1" = { "dataset1" : ["role1","role2", "role5"], "dataset2" : ["role3","role2"], }, "member2" = { "dataset3" : ["role1","role4"], "dataset2" : ["role5"], } } } locals { helper_list = flatten([for member, value in var.bq_iam_role_bindings: flatten([for dataset, roles in value: [for role in roles: {"member" = member "dataset" = dataset "role" = role} ]]) ]) } 

which will result in helper_list in the form of:

[ { "dataset" = "dataset1" "member" = "member1" "role" = "role1" }, { "dataset" = "dataset1" "member" = "member1" "role" = "role2" }, { "dataset" = "dataset1" "member" = "member1" "role" = "role5" }, { "dataset" = "dataset2" "member" = "member1" "role" = "role3" }, { "dataset" = "dataset2" "member" = "member1" "role" = "role2" }, { "dataset" = "dataset2" "member" = "member2" "role" = "role5" }, { "dataset" = "dataset3" "member" = "member2" "role" = "role1" }, { "dataset" = "dataset3" "member" = "member2" "role" = "role4" }, ] 

The above form is much easier to work with for_each, e.g.:

resource "google_bigquery_dataset_iam_binding" "reader" { for_each = { for idx, record in local.helper_list : idx => record } dataset_id = each.value.dataset role = each.value.role members = [ each.value.member ] }