Making logging configurable (#60)

* Making logging configurable
* Setting a default for bucket name
* set the default to true
* Adding the new variable into tests

.travis.yml

@@ -30,7 +30,7 @@ script:
   -
   - terraform init
   - terraform fmt -check=true
-  - terraform validate -var "region=${AWS_REGION}" -var "subnets=[]" -var "vpc_id=vpc-abcde012" -var "load_balancer_name=my-lb" -var "log_bucket_name=my-log-bucket" -var "security_groups=[]"
+  - terraform validate -var "region=${AWS_REGION}" -var "subnets=[]" -var "vpc_id=vpc-abcde012" -var "load_balancer_name=my-lb" -var "log_enable=true" -var "log_bucket_name=my-log-bucket" -var "security_groups=[]"
   - docker run --rm -v $(pwd):/app/ --workdir=/app/ -t wata727/tflint --error-with-issues
   - cd examples/alb_test_fixture
   - terraform init

main.tf

@@ -11,7 +11,7 @@ resource "aws_lb" "application" {
   tags                       = "${merge(var.tags, map("Name", var.load_balancer_name))}"
 
   access_logs {
-    enabled = true
+    enabled = "${var.log_enable}"
     bucket  = "${var.log_bucket_name}"
     prefix  = "${var.log_location_prefix}"
   }

variables.tf

@@ -80,8 +80,14 @@ variable "load_balancer_update_timeout" {
   default     = "10m"
 }
 
+variable "log_enable" {
+  description = "Enable logging"
+  default     = true
+}
+
 variable "log_bucket_name" {
   description = "S3 bucket (externally created) for storing load balancer access logs."
+  default     = ""
 }
 
 variable "log_location_prefix" {