Add ability to make s3 logger optionally. (#13)

LGTM; Merging.

README.md

@@ -35,8 +35,8 @@ For an example of using ALB with ECS look no further than the [hashicorp example
 * `certificate_arn` - . (Required if using HTTPS in `alb_protocols`)
 * `cookie_duration` - If sticky sessions via cookies are desired, set this variable to a value from 2 - 604800 seconds. (Optional)
 * `health_check_path` - Path for the load balancer to health check instances. (Optional; default: /)
-* `log_bucket` - S3 bucket where access logs should land. (Required)
-* `log_prefix` - S3 prefix within the `log_bucket` where logs should land. (Optional)
+* `log_bucket` - S3 bucket where access logs should land. If not set it will be not leave logs. (Optional; default: "")
+* `log_prefix` - S3 prefix within the `log_bucket` where logs should land. (Optional; default: "")
 * `principle_account_id` - A mapping of regions to principle account IDs used to send LB logs. (Should only change as regions are added)
 * `subnets` - ALB will be created in the subnets in this list. (Required)
 * `vpc_id` - Resources will be created in the VPC with this `id`. (Required)

alb/main.tf

@@ -21,14 +21,16 @@ resource "aws_alb" "main" {
   internal        = "${var.alb_is_internal}"
 
   access_logs {
-    bucket = "${var.log_bucket}"
-    prefix = "${var.log_prefix}"
+    bucket  = "${var.log_bucket}"
+    prefix  = "${var.log_prefix}"
+    enabled = "${var.log_bucket != ""}"
   }
 
   tags = "${merge(var.tags, map("Name", format("%s", var.alb_name)))}"
 }
 
 resource "aws_s3_bucket" "log_bucket" {
+  count         = "${var.log_bucket != "" ? 1 : 0}"
   bucket        = "${var.log_bucket}"
   policy        = "${data.template_file.bucket_policy.rendered}"
   force_destroy = true

alb/variables.tf

@@ -56,10 +56,12 @@ variable "health_check_path" {
 
 variable "log_bucket" {
   description = "S3 bucket for storing ALB access logs."
+  default     = ""
 }
 
 variable "log_prefix" {
   description = "S3 prefix within the log_bucket under which logs are stored."
+  default     = ""
 }
 
 variable "principle_account_id" {