changed variable type of vpc_config (#42)

Terraform registry marked it as required but it's optional.
This is a drop-in replacement (patch version).

modules/lambda/main.tf

@@ -18,7 +18,7 @@ resource "aws_lambda_function" "lambda" {
   timeout          = var.timeout
 
   dynamic "vpc_config" {
-    for_each = var.vpc_config == null ? [] : [var.vpc_config]
+    for_each = length(var.vpc_config) < 1 ? [] : [var.vpc_config]
     content {
       security_group_ids = vpc_config.value.security_group_ids
       subnet_ids         = vpc_config.value.subnet_ids
@@ -48,7 +48,7 @@ resource "aws_iam_role_policy_attachment" "cloudwatch_logs" {
 }
 
 resource "aws_iam_role_policy_attachment" "vpc_attachment" {
-  count = var.vpc_config == null ? 0 : 1
+  count = length(var.vpc_config) < 1 ? 0 : 1
   role  = aws_iam_role.lambda.name
 
   // see https://docs.aws.amazon.com/lambda/latest/dg/vpc.html

modules/lambda/variables.tf

@@ -58,10 +58,7 @@ variable "timeout" {
 
 variable "vpc_config" {
   description = "Provide this to allow your function to access your VPC (if both 'subnet_ids' and 'security_group_ids' are empty then vpc_config is considered to be empty or unset, see https://docs.aws.amazon.com/lambda/latest/dg/vpc.html for details)."
-  type = object({
-    security_group_ids = list(string)
-    subnet_ids         = list(string)
-  })
-  default = null
+  type        = map(list(string))
+  default     = {}
 }
 

variables.tf

@@ -85,9 +85,6 @@ variable "timeout" {
 
 variable "vpc_config" {
   description = "Provide this to allow your function to access your VPC (if both 'subnet_ids' and 'security_group_ids' are empty then vpc_config is considered to be empty or unset, see https://docs.aws.amazon.com/lambda/latest/dg/vpc.html for details)."
-  type = object({
-    security_group_ids = list(string)
-    subnet_ids         = list(string)
-  })
-  default = null
+  type        = map(list(string))
+  default     = {}
 }