Configo.Design

Configo.Design

Design-time support for Configo.

This package enables the configo schema generate dotnet tool to introspect your application's DI container and produce an appsettings.schema.json file with accurate JSON schema definitions for all your configuration sections.

How it works

Configo.Design registers a hosted service that is a no-op during normal application startups. It only activates when the application is launched by the configo schema generate tool (i.e., when the CONFIGO_GENERATING_SCHEMA=true environment variable is set).

When activated, the service discovers all bound configuration sections and writes a lightweight bindings manifest (a temp JSON file) that tells the tool which CLR types are bound to which configuration section names. It then stops the application. The tool reads this manifest, loads the application's compiled assemblies, and generates the full JSON schema using NJsonSchema — entirely within the tool process. The application itself never references NJsonSchema.

Installation

<PackageReference Include="Configo.Design">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>

Why PrivateAssets=all? This is a design-time dependency — it is only needed when running the configo schema generate tool, not during normal application execution. Using PrivateAssets=all prevents Configo.Design from flowing transitively to any project that references yours as a library.

Usage

In your Program.cs, register the schema generator alongside your other services:

// This is a no-op unless run under `configo schema generate`.
builder.Services.AddConfigoDesign();

Then run the tool from your project directory:

dotnet configo schema generate
dotnet configo schema generate --output ./appsettings.schema.json

Skipping database migrations during schema generation

When running under the tool, you may want to skip startup work (like EF Core migrations) that requires a live database. Use ConfigoDesignEnvironment.IsActive to guard it:

if (!ConfigoDesignEnvironment.IsActive)
{
    await app.Services.MigrateAsync();
}