Fix allowedVmSizes

[jsaun]

AllowedVmSizes isn't currently working after some recent refactor. The allowed vm list was being set up in the constructor before the DoOnceAtStartUpService service has had a chance to run and parse the file.

[BMurri]

The technique used here affords a way to delay the start of a subsequent background service in order to ensure that all needed initialization has been performed.

When using the IOptions pattern, its an anti-pattern to hold onto IConfiguration unless your code is actively changing configuration values.

My honest opinion is that DoOnceAtStartUpService is an anti-pattern by itself, and the operations performed here should be called from either Program.cs or Startup.cs, but I'm not going to litigate that here.

[jsaun]

I'm not quite following how you could use .Wait() in the Startup ConfigureServices method to hold off the batchscheduler singleton until after DoOnceAtStartUpService has run.

I don't have enough experience with IOptions, why is it an anti-pattern to hold onto IConfiguration. It looks like one of the first examples in Microsoft docs is doing just that: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/options?view=aspnetcore-7.0#bind-hierarchical-configuration

[BMurri]

That first example is explicitly NOT the dependency injection example. The second example is explicitly is.

The idea with the Wait is to prevent subsequent services from starting until the required initialization code has completed (so, effectively turning a Task return into the equivalent of a void return, where the return doesn't happen until the method truly has completed). My suggestion was to apply it in the DoOnceAtStartUpService itself if a means of performing the initialization could not be easily performed in the Program or Startup classes.

[MattMcL4475]

should fix this comment to be relevant too

[MattMcL4475]

should fix this comment to be relevant too