feat: validate bucket names (#102)

* #101: added validation for s3_bucket_name* input variables

* #101: remove override variable from conditional bc validation condition can only refer to tha variable being validated

* #101: try to fix validation regex error

* #101: escape backslashes

* #101: remove lookaheads from regex bc tf doesn't support them

* #101: added missing backslash escape

* fix: do not allow uppercase letters for bucket names

* fix: do not fail vailidation when bucket names are not specified

Co-authored-by: nozaq <code@nozaq.com>

variables.tf

@@ -186,11 +186,19 @@ variable "s3_bucket_name" {
   description = "If override_s3_bucket_name is true, use this bucket name instead of dynamic name with bucket_prefix"
   type        = string
   default     = ""
+  validation {
+    condition     = length(var.s3_bucket_name) == 0 || length(regexall("^[a-z0-9][a-z0-9\\-.]{1,61}[a-z0-9]$", var.s3_bucket_name)) > 0
+    error_message = "Input variable s3_bucket_name is invalid. Please refer to https://docs.aws.amazon.com/AmazonS3/latest/userguide/bucketnamingrules.html."
+  }
 }
 variable "s3_bucket_name_replica" {
   description = "If override_s3_bucket_name is true, use this bucket name for replica instead of dynamic name with bucket_prefix"
   type        = string
   default     = ""
+  validation {
+    condition     = length(var.s3_bucket_name_replica) == 0 || length(regexall("^[a-z0-9][a-z0-9\\-.]{1,61}[a-z0-9]$", var.s3_bucket_name_replica)) > 0
+    error_message = "Input variable s3_bucket_name_replica is invalid. Please refer to https://docs.aws.amazon.com/AmazonS3/latest/userguide/bucketnamingrules.html."
+  }
 }
 
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