Improvement: Better handling of cosmos database creation throughput issues

[old-guy-coder]

Describe the current behavior

Creating a SqlDatabase for Cosmos with manual or auto throughput when the SqlDatabase already exists with no dedicated throughput causes an error and prevents ASO from updating the database with error Updating offer to autoscale throughput is not allowed. Please invoke migration API to migrate this offer..

This can occur if the database is created/exists with Manual Throughput and ASO is then adopting that resource with configuration to use Auto throughput

Describe the improvement

Get ASO to trigger the migration API from the Azure REST API

• migrateToAutoscale - /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.DocumentDB/databaseAccounts/{accountName}/sqlDatabases/{databaseName}/throughputSettings/default/migrateToAutoscale, and;
• migrateToManualThroughput - /subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.DocumentDB/databaseAccounts/{accountName}/sqlDatabases/{databaseName}/throughputSettings/default/migrateToManualThroughput if the ASO configuration is transitioning between Manual and Autoscale or visa-versa.

Additional context

None

[theunrepentantgeek]

I believe this could be achieved by implementing the PreReconciliationChecker interface. This extension point receives the current status of the resource, allowing the check to be performed - a migration could be triggered, and Block returned from the extension point.