Hosting.Keycloak: Fix importDirectory param validation in WithRealmImport

[radical]

Description

The import path is expected to be relative to the AppHost path, but here
it was being used as-is - relative to the current working directory.
Instead, expand the path relative to the AppHost path and use that for Directory.Exists check.

This manifested as a failure to import the file when running the app
with Aspire.Hosting.Testing which would start the apphost with
cwd!=apphost .

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue:
  • No

Microsoft Reviewers: Open in CodeFlow

[radical]

cc @julioct

[radical]

We can drop the changes in TestingAppHost1, but then we need to add a test somewhere else. I did try adding Keycloak playground app to the tests for which /alive, and /health work fine but /weatherforecast fails with Endpoint 'http://localhost:52119/weatherforecast' for resource 'apiservice' in app 'Keycloak.AppHost' returned status code Unauthorized.

aspire/playground/keycloak/Keycloak.ApiService/Program.cs

Lines 28 to 40 in 972f9a9

	app.MapGet("/weatherforecast", () =>
	{
	var forecast = Enumerable.Range(1, 5).Select(index =>
	new WeatherForecast
	(
	DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
	Random.Shared.Next(-20, 55),
	summaries[Random.Shared.Next(summaries.Length)]
	))
	.ToArray();
	return forecast;
	})
	.RequireAuthorization();

[radical]

Looks like WithBindMount does not expect the path to exist. And ContainerMountAnnotation even allows a null source path.

aspire/src/Aspire.Hosting/ApplicationModel/ContainerMountAnnotation.cs

Lines 18 to 19 in ac3dbc4

	/// <param name="source">The source path if a bind mount or name if a volume. Can be <c>null</c> if the mount is an anonymous volume.</param>
	/// <param name="target">The target path of the mount.</param>

I'll restore the check, and expand the path using the apphost path.

[julioct]

LGTM

[radical]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[radical]

Merge after #5276 .