@Anonymous Thanks for reaching out. For web apps you can leverage the REST API below to start/stop/restart the app service.
Stop webapp: https://learn.microsoft.com/en-us/rest/api/appservice/web-apps/stop
Start webapp: https://learn.microsoft.com/en-us/rest/api/appservice/web-apps/start
Restart webapp: https://learn.microsoft.com/en-us/rest/api/appservice/web-apps/restart
To get started with Azure REST API you can refer to this document. In your custom application you can call the above REST API to perform different operation.
There is no operation such as start/stop the service bus. Once you have created the resource you will be billed as per the SKU of the Azure service bus. The only way to stop the billing is to delete the service. Please refer to service bus pricing document for more details.
For service bus REST operation, you can refer to this document.
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