fix: added validation to CBR input (#117)

Author: aamadeuss

README.md

@@ -170,7 +170,7 @@ You need the following permissions to run this module.
 | <a name="input_access_key_name"></a> [access\_key\_name](#input\_access\_key\_name) | The name to give the default IBM Cloud Monitoring Manager access key. Use `disable_access_key_creation` to disable access key creation. For guidance on access keys, see [here](https://cloud.ibm.com/docs/monitoring?topic=monitoring-access_key). | `string` | `"SysdigManagerKey"` | no |
 | <a name="input_access_key_tags"></a> [access\_key\_tags](#input\_access\_key\_tags) | Tags associated with the IBM Cloud Monitoring access key. | `list(string)` | `[]` | no |
 | <a name="input_access_tags"></a> [access\_tags](#input\_access\_tags) | Access Management Tags associated with the IBM Cloud Monitoring instance (Optional, array of strings). | `list(string)` | `[]` | no |
-| <a name="input_cbr_rules"></a> [cbr\_rules](#input\_cbr\_rules) | (Optional, list) List of context-based restrictions 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_disable_access_key_creation"></a> [disable\_access\_key\_creation](#input\_disable\_access\_key\_creation) | When set to true, disables the creation of a default manager access key which is required by agents to ingest metrics. | `bool` | `false` | no |
 | <a name="input_enable_platform_metrics"></a> [enable\_platform\_metrics](#input\_enable\_platform\_metrics) | Receive platform metrics in the provisioned IBM Cloud Monitoring instance. Only 1 instance in a given region can be enabled for platform metrics. | `bool` | `false` | no |
 | <a name="input_instance_name"></a> [instance\_name](#input\_instance\_name) | The name of the IBM Cloud Monitoring instance to create. Defaults to 'cloud-monitoring-<region>' | `string` | `null` | no |

variables.tf

@@ -123,7 +123,11 @@ variable "cbr_rules" {
       }))
     })))
   }))
-  description = "(Optional, list) List of context-based restrictions rules to create"
+  description = "The context-based restrictions rule to create. Only one rule is allowed."
   default     = []
   # Validation happens in the rule module
+  validation {
+    condition     = length(var.cbr_rules) <= 1
+    error_message = "Only one CBR rule is allowed."
+  }
 }