Terraform Outputs across modules - variables

Question

I am struggling to work out how to pass outputs from a module and to consume it an another.
My folder structure:
.
├── main.tf
├── modules
│   ├── cloudwatch-event
│   │   ├── basic_event_rule.tf
│   │   ├── basic_event_target.tf
│   │   └── variables.tf
│   └── lambda
│      ├── basic_lambda.tf
│      ├── output.tf
│      ├── lambda.py
│      └── variables.tf
├── lambda
│   ├── main.tf
│   └── variables.tf
└── terraform.tfvar
In order to add scheduling to the lambda, i need to consume the Lambda ARN in to the CloudWatch module.
The lambda - basic_lambda.tf
resource "aws_lambda_function" "lambda_function" {
The lambda - outputs.tf
output "lambda_arn" {
value = "${aws_lambda_function.lambda_function.arn}"
In my lambda application module, i have this in my main lambda/main.tf
module "cloudwatch-event" {
source = "../modules/cloudwatch-event"
lambda_arn = "${module.lambda.lambda_arn}"
module "lambda" {
source = "../modules/lambda"
My lambda/variables.tf includes the lambda_arn variable as a string
variable "lambda_arn" {
type = "string"
}
The root main file looks like this:
provider "aws" {
region = var.aws_region
}
module "accesskey-lambda" {
source = "./lambda/"
}
Running TF i get this
Error: Missing required argument
on main.tf line 5, in module "accesskey-lambda":
5: module "accesskey-lambda" {
The argument "lambda_arn" is required, but no definition was found.
then adding it to the root main file doesnt resolve my issues.
Thanks
Nick

Answer 1

Solved, i had a typo
in the cloudwatch/basic_event_target.tf
arn = "${var.lambda_arn}"
Then in the cloudwatch/variable
variable "lambda_arn" {
type = string
}
The module then needed
module "cloudwatch-event" {
source = "../modules/cloudwatch-event"
lambda_arn = "${module.lambda.lambda_arn}"
}