fix: added validation to CBR input (#787)

Author: aamadeuss

README.md

@@ -160,7 +160,7 @@ For more info, see [Understanding user roles and resources](https://cloud.ibm.co
 | Name | Description | Type | Default | Required |
 |------|-------------|------|---------|:--------:|
 | <a name="input_access_tags"></a> [access\_tags](#input\_access\_tags) | A list of access tags to apply to the Key Protect instance. Only used if 'create\_key\_protect\_instance' is set to `true`. | `list(string)` | `[]` | no |
-| <a name="input_cbr_rules"></a> [cbr\_rules](#input\_cbr\_rules) | (Optional, list) List of context-based restriction rules to create | <pre>list(object({<br/>    description = string<br/>    account_id  = string<br/>    rule_contexts = list(object({<br/>      attributes = optional(list(object({<br/>        name  = string<br/>        value = string<br/>    }))) }))<br/>    enforcement_mode = string<br/>    operations = optional(list(object({<br/>      api_types = list(object({<br/>        api_type_id = string<br/>      }))<br/>    })))<br/>  }))</pre> | `[]` | no |
+| <a name="input_cbr_rules"></a> [cbr\_rules](#input\_cbr\_rules) | The context-based restrictions rule to create. Only one rule is allowed. | <pre>list(object({<br/>    description = string<br/>    account_id  = string<br/>    rule_contexts = list(object({<br/>      attributes = optional(list(object({<br/>        name  = string<br/>        value = string<br/>    }))) }))<br/>    enforcement_mode = string<br/>    operations = optional(list(object({<br/>      api_types = list(object({<br/>        api_type_id = string<br/>      }))<br/>    })))<br/>  }))</pre> | `[]` | no |
 | <a name="input_create_key_protect_instance"></a> [create\_key\_protect\_instance](#input\_create\_key\_protect\_instance) | A flag to control whether a Key Protect instance is created. The default is `true`. | `bool` | `true` | no |
 | <a name="input_dual_auth_delete_enabled"></a> [dual\_auth\_delete\_enabled](#input\_dual\_auth\_delete\_enabled) | If set to `true`, a dual authorization policy is enabled on the Key Protect instance. After the dual authorization policy is set on the instance, it cannot be reverted. An instance with dual authorization policy enabled cannot be destroyed by using Terraform. Only used if 'create\_key\_protect\_instance' is set to `true`. | `bool` | `false` | no |
 | <a name="input_enable_metrics"></a> [enable\_metrics](#input\_enable\_metrics) | Set to `true` to enable metrics on the Key Protect instance. Only used if 'create\_key\_protect\_instance' is set to `true`. In order to view metrics, you need an IBM Cloud Monitoring (Sysdig) instance that is located in the same region as the Key Protect instance. After you provision a Monitoring instance, enable platform metrics to monitor your Key Protect instance. | `bool` | `true` | no |

variables.tf

@@ -182,7 +182,7 @@ variable "cbr_rules" {
       }))
     })))
   }))
-  description = "(Optional, list) List of context-based restriction rules to create"
+  description = "The context-based restrictions rule to create. Only one rule is allowed."
   default     = []
   # Validation happens in the rule module
   # NOTE: Context-based restriction rules applies to Key Protect instances only and is not supported by Hyper Protect Crypto Services (HPCS) instances
@@ -192,4 +192,8 @@ variable "cbr_rules" {
     condition     = var.existing_kms_instance_crn == null ? true : length(regexall(".*hscrypto.*", var.existing_kms_instance_crn)) > 0 ? length(var.cbr_rules) == 0 : true
     error_message = "When passing a Hyper Protect Crypto Services (HPCS) instance as a value for `existing_kms_instance_crn` you cannot provide `cbr_rules`. Context-based restrictions are not supported by HPCS instances. For more information, go to [services that integrate with context-based restrictions](https://cloud.ibm.com/docs/account?topic=account-context-restrictions-whatis#cbr-adopters)."
   }
+  validation {
+    condition     = length(var.cbr_rules) <= 1
+    error_message = "Only one CBR rule is allowed."
+  }
 }