Enable Scheduled Shutdown of Guacamole Linux VMs

[marrobi]

As a user I want to specify a time that the VM will automatically shutdown each day to reduce costs.

This needs to be provided in the UI, hence the bundle template schema json will need updating, hence porter yaml, and terraform.

The terraform resource required can be found here.

https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/dev_test_global_vm_shutdown_schedule

[TonyWildish-BH]

@marrobi, we have an implementation we're testing now that takes a different approach. We use an Azure Automation Runbook to look for VMs in resource groups matching rg-${tre_id}-ws-, and monitor them for being idle(*). Then we shut them down. This is better than having a schedule as we have people who work odd hours, and using a schedule can still lead to significant idle time.

We want to extend this, with a "don't shut me down" flag in the VM template, which will add a tag to that VM. Such tagged VMs will be skipped in the shutdown process, and it's up to the user to take care of them. There are edge cases we can foresee where this could be useful.

We can look at contributing this back in the new year if people are interested?

(*) 'idle' is defined as (up for at least one hour) AND (averaging < x% CPU during the last hour)

[marrobi]

As always, we welcome contributions that will be useful for others. I think its potentially two separate features, one to do it on a schedule, ne to do it when idle.