Keep it DRY.

functions.tf

@@ -4,6 +4,7 @@ locals {
     "_dns",
     "gitlab",
   ]
+  function_names = [for name in local.functions : "${local.function_name_prefix}-${replace(name, "_", "")}"]
 }
 
 data "aws_iam_policy_document" "lambda_assume_policy" {
@@ -93,7 +94,7 @@ output "timeout" {
 resource "aws_lambda_function" "function" {
   count             = length(local.functions)
   runtime           = var.runtime
-  function_name     = "${local.function_name_prefix}-${replace(local.functions[count.index], "_", "")}"
+  function_name     = local.function_names[count.index]
   role              = local.lambda_role_arn
   source_code_hash  = filebase64sha256("payload.zip")
   s3_bucket         = local.payloads_bucket_name
@@ -124,7 +125,6 @@ resource "aws_lambda_function" "function" {
 
 locals {
   function_arns     = aws_lambda_function.function.*.arn
-  function_names    = aws_lambda_function.function.*.id
   function_versions = aws_lambda_function.function.*.version
 }
 

log-groups.tf

 resource "aws_cloudwatch_log_group" "lambda" {
-  count             = length(local.functions)
-  name              = "/aws/lambda/${local.function_name_prefix}_${local.functions[count.index]}"
+  count             = length(local.function_names)
+  name              = "/aws/lambda/${local.function_names[count.index]}"
   retention_in_days = var.log_retention
   tags              = local.common_tags
 }