######### Here in main.tf  we use module to create lambda function and invoke it:

module "get_params" {
  source                    = "../../modules/lambda"
  file_name                 = module.get_params_archive.path
  lambda_function_file_name = "get_params"
  function_name             = "get_params"

  invocation = "true"

  environment = merge(map(
    "project", local.project,
    "query", "[ \"key1\", \"key2\" ]"
  ))

}

######### This is in "../../modules/lambda" files, shortened:
### the function creation
resource "aws_lambda_function" "this" {
  filename                       = var.file_name
  function_name                  = local.name
  ...
}

### invocation (var.creation is true)
data "aws_lambda_invocation" "this" {
  count = var.invocation == "true" && var.creation == "true" ? 1 : 0
  function_name = aws_lambda_function.this.function_name

  input = <<JSON
{
  "Name": "Invocation"
}
JSON
}

### output of the module
output "result_map" {
  description = "if result is a map"
  value = data.aws_lambda_invocation.this.*.result_map
}

######### return back to the main code: here's how I get the output to check we have at least something and the lambda works :

output "out_params_map" {
  description = "something"
  value = module.get_params.result_map
}