KubeOps Generator

This is a C# source generator for KubeOps and operators. It is used to generate convenience functions to help registering resources within an operator.

Motivation

The primary goal of this generator is to reduce boilerplate code required in your operator's Program.cs (or startup logic). Instead of manually calling builder.AddController<...>(), builder.AddFinalizer<...>(), builder.AddWebhook<...>(), etc., for every component, the generator scans your project and creates extension methods that register all discovered components with a single call.

Usage

The generator is automatically used when the KubeOps.Generator package is referenced.

dotnet add package KubeOps.Generator

which results in the following csproj reference:

<ItemGroup>
    <PackageReference Include="KubeOps.Generator" Version="...">
        <PrivateAssets>all</PrivateAssets>
        <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
    </PackageReference>
</ItemGroup>

Once referenced, you typically use the main generated extension method in your Program.cs:

using KubeOps.Operator;

var builder = WebApplication.CreateBuilder(args);

// Add KubeOps services and register all discovered components
builder.Services
    .AddKubernetesOperator()
    .RegisterComponents(); // <--- Generated extension method

// ... other service registrations

var app = builder.Build();
// ... configure middleware
app.RunOperatorAsync();

Generated Sources

The generator will automatically generate functions for the IOperatorBuilder.

Entity Metadata / Entity Definitions

The generator creates a file in the root namespace called EntityDefinitions.g.cs. This file contains all entities that are annotated with the KubernetesEntityAttribute. The static class contains the EntityMetadata for the entities as well as a function to register all entities within the IOperatorBuilder.

Example

using KubeOps.Abstractions.Builder;
using KubeOps.Abstractions.Entities;

public static class EntityDefinitions
{
    public static readonly EntityMetadata V1TestEntity = new("TestEntity", "v1", "testing.dev", null);
    public static IOperatorBuilder RegisterEntities(this IOperatorBuilder builder)
    {
        builder.AddEntity<global::Operator.Entities.V1TestEntity>(V1TestEntity);
        return builder;
    }
}

Entity Initializer

All entities must have their Kind and ApiVersion fields set. To achieve this, the generator creates an initializer file for each entity that is annotated with the KubernetesEntityAttribute.

For each partial class that does not contain a default constructor, the generator will create a default constructor that sets the Kind and ApiVersion fields.

For each non partial class, a method extension is created that sets the Kind and ApiVersion fields.

Note

Setting your class partial is crucial for the generator to create the constructor. Also, if some default constructor is already present, the generator uses the method extension fallback.

Example

namespace Operator.Entities;

[KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
public partial class V1TestEntity : CustomKubernetesEntity
{
}

The partial defined entity above will generate the following V1TestEntity.init.g.cs file:

namespace Operator.Entities;
public partial class V1TestEntity
{
    public V1TestEntity()
    {
        ApiVersion = "testing.dev/v1";
        Kind = "TestEntity";
    }
}

The non partial defined entity below:

namespace Operator.Entities;

[KubernetesEntity(Group = "testing.dev", ApiVersion = "v1", Kind = "TestEntity")]
public class V1TestEntity : CustomKubernetesEntity
{
}

will generate a static method extension in EntityInitializer.g.cs for the entity to initialize the fields:

public static class EntityInitializer
{
    public static global::Operator.Entities.V1ClusterTestEntity Initialize(this global::Operator.Entities.V1ClusterTestEntity entity)
    {
        entity.ApiVersion = "testing.dev/v1";
        entity.Kind = "ClusterTestEntity";
        return entity;
    }
}

Controller Registrations

The generator creates a file in the root namespace called ControllerRegistrations.g.cs. This file contains a function to register all found controllers (i.e. classes that implement the IResourceController<TEntity> interface).

Example

using KubeOps.Abstractions.Builder;

public static class ControllerRegistrations
{
    public static IOperatorBuilder RegisterControllers(this IOperatorBuilder builder)
    {
        builder.AddController<global::Operator.Controller.V1TestEntityController, global::Operator.Entities.V1TestEntity>();
        return builder;
    }
}

Finalizer Registrations

The generator creates a file in the root namespace called FinalizerRegistrations.g.cs. This file contains all finalizers with generated finalizer-identifiers. Further, a function to register all finalizers (i.e., classes that implement IResourceFinalizer<TEntity>) is generated.

Example

using KubeOps.Abstractions.Builder;

public static class FinalizerRegistrations
{
    public const string FinalizerOneIdentifier = "testing.dev/finalizeronefinalizer";
    public const string FinalizerTwoIdentifier = "testing.dev/finalizertwofinalizer";
    public static IOperatorBuilder RegisterFinalizers(this IOperatorBuilder builder)
    {
        builder.AddFinalizer<global::Operator.Finalizer.FinalizerOne, global::Operator.Entities.V1TestEntity>(FinalizerOneIdentifier);
        builder.AddFinalizer<global::Operator.Finalizer.FinalizerTwo, global::Operator.Entities.V1TestEntity>(FinalizerTwoIdentifier);
        return builder;
    }
}

Webhook Registrations

The generator creates a file in the root namespace called WebhookRegistrations.g.cs. This file contains a function to register all found webhooks (i.e., classes decorated with [ValidationWebhook], [MutationWebhook], or [ConversionWebhook]).

Example

using KubeOps.Abstractions.Builder;

public static class WebhookRegistrations
{
    public static IOperatorBuilder RegisterWebhooks(this IOperatorBuilder builder)
    {
        // Example assuming MyValidationWebhook and MyMutationWebhook exist
        builder.AddValidationWebhook<global::Operator.Webhooks.MyValidationWebhook, global::Operator.Entities.V1TestEntity>();
        builder.AddMutationWebhook<global::Operator.Webhooks.MyMutationWebhook, global::Operator.Entities.V1TestEntity>();
        return builder;
    }
}

General Operator Extensions

The generator creates a file in the root namespace called OperatorExtensions.g.cs. It contains convenience functions to register all generated sources.

Example

using KubeOps.Abstractions.Builder;

public static class OperatorBuilderExtensions
{
    public static IOperatorBuilder RegisterComponents(this IOperatorBuilder builder)
    {
        builder.RegisterEntities();
        builder.RegisterWebhooks();
        builder.RegisterControllers();
        builder.RegisterFinalizers();
        return builder;
    }
}

Troubleshooting

  • Generated files not visible? Source generators add files during the build process. They might not appear directly in your Visual Studio Solution Explorer unless you explicitly look in the obj/Debug/netX.Y/generated/KubeOps.Generator folder or use features like VS's "Show all files".
  • Changes not picked up? If you add a new controller/finalizer/webhook and it's not being registered, ensure your project compiles successfully and try rebuilding the solution.
  • Entity Initializer not working? Make sure your entity class is marked partial and does not have an explicitly defined parameterless constructor if you want the generator to create one.
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