Model Dapr sidecar as an Aspire resource

[philliphoff]

Currently, Dapr sidecars are modeled as annotations on a parent resource, which indicates the need for a Dapr sidecar started for that resource. The Dapr lifecycle hook will then generate appropriate Dapr CLI executable resources to start the sidecars. When publishing, that hook will write Dapr sidecar resources to the manifest.

This model has a disadvantage in that, because the sidecars are not true resources, users cannot modify them like other resources (e.g. set environment variables). This was done originally due to the tight 1:1 mapping between Dapr sidecar and parent resource. For example, it would be semantically invalid to create a Dapr sidecar resource and then reference it from several resources.

This PR updates the model such that the Dapr sidecar is a true resource, but one exposed only through the existing AddDaprSidecar() API to avoid semantic errors; users cannot create an arbitrary Dapr sidecar resource, only configure the one associated with a given resource. The API allows the existing sidecar options (if any) to be specified, as well as use the existing resource annotation helpers, such as WithEnvironment().

The API looks like:

builder.AddProject<Projects.DaprServiceA>("servicea")
       .WithDaprSidecar(
                 sidecarBuilder =>
                 {
                     sidecarBuilder
                         .WithOptions(new DaprSidecarOptions { ... })
                         .WithEnvironment("DAPR_TEST_VAR", "Dapr Test Value");
                 }
       )

NOTE: Currently only the environment variables annotations are applied to the implicit Dapr CLI executable resource.

Resolves #1553

Microsoft Reviewers: Open in CodeFlow

[davidfowl]

We'll end up having 3 resources in the UI once we do this #436

[philliphoff]

We'll end up having 3 resources in the UI once we do this #436

I'm ok with that, though I'm curious as to what the UX for that will be like. It'd be neat to be able to arrange the resources in some sort of hierarchical way.

[GFlisch]

Any idea when the preview3 with this feature will be available?

[davidfowl]

February is the next release. You can use ci builds to help verify this feature though.

[bit365]

thanks ^_^