Dapr Component Specification Validation (+ Source Generators)

[FullStackChef]

Related to an existing integration?

Yes

Existing integration

Hosting.Dapr

Overview

By leveraging source generators, we can create a strongly-typed, fluent builder interface that encapsulates the component metadata.

For example, rather than working with untyped dictionaries, the source generator would produce metadata classes (like RedisStateMetadata) with defined properties:

public class RedisStateMetadata
{
    public string RedisHost { get; set; }
    public int RedisPort { get; set; }
    public SecretRef RedisPassword { get; set; }
}

• Catch Errors Early: Identify misconfigurations before the application even runs.
• Enforce Consistency: Ensure that every component adheres to its expected schema.
• Improve Developer Experience: Provide immediate feedback through compile-time warnings or errors, reducing runtime surprises.
• The goal is to offer a robust, type-safe mechanism that validates the Dapr component specifications, thereby increasing reliability and reducing debugging time.

Usage example

1. Fluent Chaining

This approach uses individual fluent methods to configure each property:

var builder = new DaprComponentBuilder();

builder.AddDaprRedisStateStore("myDaprRedisStateStore")
    .WithHost("127.0.0.1")
    .WithPort(6379)
    .WithPassword(passwordParam);

Here, AddDaprRedisStateStore("myDaprRedisStateStore") initializes the configuration for a Redis state store with the provided name. The subsequent fluent methods (WithHost, WithPort, and WithPassword) configure the strongly typed RedisStateMetadata.

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2. Lambda Configuration in the Method

This variant offers an overload that accepts an Action<RedisStateMetadata> for inline configuration:

var builder = new DaprComponentBuilder();

builder.AddDaprRedisStateStore("myDaprRedisStateStore", metadata =>
{
    metadata.RedisHost = "127.0.0.1";
    metadata.RedisPort = 6379;
    metadata.RedisPassword = passwordParam;
});

This API variant bundles the configuration into a single call, offering a compact way to set up the metadata.

---

3. WithMetadata Extension

The third approach separates the initial resource creation from metadata configuration using a dedicated WithMetadata method:

var builder = new DaprComponentBuilder();

builder.AddDaprRedisStateStore("myDaprRedisStateStore")
    .WithMetadata(metadata =>
    {
        metadata.RedisHost = "127.0.0.1";
        metadata.RedisPort = 6379;
        metadata.RedisPassword = passwordParam;
    });

In this scenario, AddDaprRedisStateStore first creates the state store resource, and then WithMetadata allows you to configure the associated metadata using a lambda expression. This approach maintains the separation of concerns while still providing a fluent and strongly typed configuration experience.

Breaking change?

Yes

Alternatives

Each of the apis would support the future generation of a WithReference API that can be used to provide a rich experience for configuring dapr components based on aspire managed resources

Additional context

No response

Help us help you

Yes, I'd like to be assigned to work on this item

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