Fix rds_instance module… (#56220)

* Fix rds_instance module to run against an (older) existing RDS instance successfully

* Only pop Iops param if no storage_type is given. If given and set to wrong type we get to the AWS client error that informs the user

* Docs syntax fix

* Fix typo in docs

Co-Authored-By: stefanhorning <stefan@hornings.de>

lib/ansible/modules/cloud/amazon/rds_instance.py

@@ -212,7 +212,7 @@ options:
         type: bool
     iops:
         description:
-          - The Provisioned IOPS (I/O operations per second) value.
+          - The Provisioned IOPS (I/O operations per second) value. Is only set when using I(storage_type) is set to io1.
         type: int
     kms_key_id:
         description:
@@ -846,6 +846,8 @@ def get_options_with_changing_values(client, module, parameters):
         parameters.pop('MasterUserPassword', None)
     if cloudwatch_logs_enabled:
         parameters['CloudwatchLogsExportConfiguration'] = cloudwatch_logs_enabled
+    if not module.params['storage_type']:
+        parameters.pop('Iops')
 
     instance = get_instance(client, module, instance_id)
     updated_parameters = get_changing_options_with_inconsistent_keys(parameters, instance, purge_cloudwatch_logs)
@@ -890,7 +892,8 @@ def get_current_attributes_with_inconsistent_keys(instance):
     options['DBParameterGroupName'] = [parameter_group['DBParameterGroupName'] for parameter_group in instance['DBParameterGroups']]
     options['AllowMajorVersionUpgrade'] = None
     options['EnableIAMDatabaseAuthentication'] = instance['IAMDatabaseAuthenticationEnabled']
-    options['EnablePerformanceInsights'] = instance['PerformanceInsightsEnabled']
+    # PerformanceInsightsEnabled is not returned on older RDS instances it seems
+    options['EnablePerformanceInsights'] = instance.get('PerformanceInsightsEnabled', False)
     options['MasterUserPassword'] = None
     options['NewDBInstanceIdentifier'] = instance['DBInstanceIdentifier']