feat: add runtime generated entity clients

Author: Christoph Bühler

src/KubeOps.Abstractions/Builder/IOperatorBuilder.cs

@@ -21,41 +21,40 @@ public interface IOperatorBuilder
 
     /// <summary>
     /// <para>
-    /// Register an entity within the operator.
-    /// Entities must be registered to be used in controllers and other
-    /// elements like Kubernetes clients.
-    /// </para>
-    /// <para>
-    /// This method will also register a transient IKubernetesClient{TEntity} for
-    /// the entity.
+    /// Register an entity Kubernetes client within the operator.
+    /// This is used to register IKubernetesClient{TEntity} for the entity.
+    /// An alternative way to create any Kubernetes client is to use the
+    /// KubernetesClientFactory or instantiate the client by yourself.
     /// </para>
     /// </summary>
     /// <param name="metadata">The metadata of the entity.</param>
     /// <typeparam name="TEntity">The type of the entity.</typeparam>
     /// <returns>The builder for chaining.</returns>
-    IOperatorBuilder AddEntity<TEntity>(EntityMetadata metadata)
+    IOperatorBuilder AddEntityClient<TEntity>(EntityMetadata metadata)
         where TEntity : IKubernetesObject<V1ObjectMeta>;
 
     /// <summary>
-    /// Add a controller implementation for a specific entity to the operator.
-    /// The metadata for the entity must be added as well.
+    /// <para>
+    /// Register an entity Kubernetes client within the operator.
+    /// This is used to register IKubernetesClient{TEntity} for the entity.
+    /// An alternative way to create any Kubernetes client is to use the
+    /// KubernetesClientFactory or instantiate the client by yourself.
+    /// This method uses reflection to get the metadata from the entity.
+    /// </para>
     /// </summary>
-    /// <typeparam name="TImplementation">Implementation type of the controller.</typeparam>
-    /// <typeparam name="TEntity">Entity type.</typeparam>
+    /// <typeparam name="TEntity">The type of the entity.</typeparam>
     /// <returns>The builder for chaining.</returns>
-    IOperatorBuilder AddController<TImplementation, TEntity>()
-        where TImplementation : class, IEntityController<TEntity>
+    IOperatorBuilder AddEntityClient<TEntity>()
         where TEntity : IKubernetesObject<V1ObjectMeta>;
 
     /// <summary>
-    /// Add a controller implementation for a specific entity with the
-    /// entity metadata.
+    /// Add a controller implementation for a specific entity to the operator.
+    /// The metadata for the entity must be added as well.
     /// </summary>
-    /// <param name="metadata">The metadata of the entity.</param>
     /// <typeparam name="TImplementation">Implementation type of the controller.</typeparam>
     /// <typeparam name="TEntity">Entity type.</typeparam>
     /// <returns>The builder for chaining.</returns>
-    IOperatorBuilder AddControllerWithEntity<TImplementation, TEntity>(EntityMetadata metadata)
+    IOperatorBuilder AddController<TImplementation, TEntity>()
         where TImplementation : class, IEntityController<TEntity>
         where TEntity : IKubernetesObject<V1ObjectMeta>;
 

src/KubeOps.Generator/Generators/EntityDefinitionGenerator.cs

@@ -98,7 +98,7 @@ public void Execute(GeneratorExecutionContext context)
                                         MemberAccessExpression(
                                             SyntaxKind.SimpleMemberAccessExpression,
                                             IdentifierName("builder"),
-                                            GenericName(Identifier("AddEntity"))
+                                            GenericName(Identifier("AddEntityClient"))
                                                 .WithTypeArgumentList(
                                                     TypeArgumentList(
                                                         SingletonSeparatedList<TypeSyntax>(

src/KubeOps.Operator/Builder/OperatorBuilder.cs

@@ -13,6 +13,7 @@
 using KubeOps.Abstractions.Finalizer;
 using KubeOps.Abstractions.Queue;
 using KubeOps.KubernetesClient;
+using KubeOps.Operator.Client;
 using KubeOps.Operator.Finalizer;
 using KubeOps.Operator.Queue;
 using KubeOps.Operator.Watcher;
@@ -35,10 +36,17 @@ public OperatorBuilder(IServiceCollection services, OperatorSettings settings)
 
     public IServiceCollection Services { get; }
 
-    public IOperatorBuilder AddEntity<TEntity>(EntityMetadata metadata)
+    public IOperatorBuilder AddEntityClient<TEntity>(EntityMetadata metadata)
         where TEntity : IKubernetesObject<V1ObjectMeta>
     {
-        Services.AddTransient<IKubernetesClient<TEntity>>(_ => new KubernetesClient<TEntity>(metadata));
+        Services.AddTransient<IKubernetesClient<TEntity>>(_ => KubernetesClientFactory.Create<TEntity>(metadata));
+        return this;
+    }
+
+    public IOperatorBuilder AddEntityClient<TEntity>()
+        where TEntity : IKubernetesObject<V1ObjectMeta>
+    {
+        Services.AddTransient<IKubernetesClient<TEntity>>(_ => KubernetesClientFactory.Create<TEntity>());
         return this;
     }
 
@@ -62,11 +70,6 @@ public IOperatorBuilder AddController<TImplementation, TEntity>()
         return this;
     }
 
-    public IOperatorBuilder AddControllerWithEntity<TImplementation, TEntity>(EntityMetadata metadata)
-        where TImplementation : class, IEntityController<TEntity>
-        where TEntity : IKubernetesObject<V1ObjectMeta> =>
-        AddController<TImplementation, TEntity>().AddEntity<TEntity>(metadata);
-
     public IOperatorBuilder AddFinalizer<TImplementation, TEntity>(string identifier)
         where TImplementation : class, IEntityFinalizer<TEntity>
         where TEntity : IKubernetesObject<V1ObjectMeta>
@@ -86,7 +89,8 @@ private static Func<IServiceProvider, EntityFinalizerAttacher<TImplementation, T
         => services => async entity =>
         {
             var logger = services.GetService<ILogger<EntityFinalizerAttacher<TImplementation, TEntity>>>();
-            var client = services.GetRequiredService<IKubernetesClient<TEntity>>();
+            using var client = services.GetService<IKubernetesClient<TEntity>>() ??
+                               KubernetesClientFactory.Create<TEntity>();
 
             logger?.LogTrace(
                 """Try to add finalizer "{finalizer}" on entity "{kind}/{name}".""",
@@ -206,14 +210,13 @@ private static Func<IServiceProvider, EventPublisher> CreateEventPublisher()
     private void AddOperatorBase()
     {
         Services.AddSingleton(_settings);
-        Services.AddTransient<IKubernetesClient<Corev1Event>>(_ => new KubernetesClient<Corev1Event>(new(
-            Corev1Event.KubeKind, Corev1Event.KubeApiVersion, Plural: Corev1Event.KubePluralName)));
+
+        Services.AddTransient(_ => KubernetesClientFactory.Create<Corev1Event>());
         Services.AddTransient(CreateEventPublisher());
 
         if (_settings.EnableLeaderElection)
         {
-            using var client = new KubernetesClient<Corev1Event>(new(
-                Corev1Event.KubeKind, Corev1Event.KubeApiVersion, Plural: Corev1Event.KubePluralName));
+            using var client = KubernetesClientFactory.Create<Corev1Event>();
 
             var elector = new LeaderElector(
                 new LeaderElectionConfig(

src/KubeOps.Operator/Client/KubernetesClientFactory.cs

@@ -0,0 +1,36 @@
+using k8s;
+using k8s.Models;
+
+using KubeOps.Abstractions.Entities;
+using KubeOps.KubernetesClient;
+using KubeOps.Transpiler;
+
+namespace KubeOps.Operator.Client;
+
+/// <summary>
+/// Factory to create a <see cref="IKubernetesClient{TEntity}"/> for a given <see cref="EntityMetadata"/>
+/// or type.
+/// </summary>
+public static class KubernetesClientFactory
+{
+    /// <summary>
+    /// Create a <see cref="IKubernetesClient{TEntity}"/> for a given <see cref="EntityMetadata"/>.
+    /// This method does not use reflection at runtime since the metadata is already provided.
+    /// </summary>
+    /// <param name="metadata">Metadata for the entity.</param>
+    /// <typeparam name="TEntity">Type of the entity.</typeparam>
+    /// <returns>The created <see cref="IKubernetesClient{TEntity}"/>.</returns>
+    public static IKubernetesClient<TEntity> Create<TEntity>(EntityMetadata metadata)
+        where TEntity : IKubernetesObject<V1ObjectMeta> =>
+        new KubernetesClient<TEntity>(metadata);
+
+    /// <summary>
+    /// Create a <see cref="IKubernetesClient{TEntity}"/> for a given type.
+    /// This method uses reflection at runtime to fetch the metadata for the entity.
+    /// </summary>
+    /// <typeparam name="TEntity">Type of the entity.</typeparam>
+    /// <returns>The created <see cref="IKubernetesClient{TEntity}"/>.</returns>
+    public static IKubernetesClient<TEntity> Create<TEntity>()
+        where TEntity : IKubernetesObject<V1ObjectMeta> =>
+        Create<TEntity>(Entities.ToEntityMetadata(typeof(TEntity)).Metadata);
+}

src/KubeOps.Operator/KubeOps.Operator.csproj

@@ -22,6 +22,7 @@
     <ItemGroup>
         <ProjectReference Include="..\KubeOps.Abstractions\KubeOps.Abstractions.csproj"/>
         <ProjectReference Include="..\KubeOps.KubernetesClient\KubeOps.KubernetesClient.csproj" />
+        <ProjectReference Include="..\KubeOps.Transpiler\KubeOps.Transpiler.csproj" />
     </ItemGroup>
 
     <ItemGroup>

src/KubeOps.Operator/Watcher/LeaderAwareResourceWatcher{TEntity}.cs

@@ -19,11 +19,10 @@ internal class LeaderAwareResourceWatcher<TEntity> : ResourceWatcher<TEntity>
     public LeaderAwareResourceWatcher(
         ILogger<LeaderAwareResourceWatcher<TEntity>> logger,
         IServiceProvider provider,
-        IKubernetesClient<TEntity> client,
         TimedEntityQueue<TEntity> queue,
         OperatorSettings settings,
         LeaderElector elector)
-        : base(logger, provider, client, queue, settings)
+        : base(logger, provider, queue, settings)
     {
         _logger = logger;
         _elector = elector;

src/KubeOps.Operator/Watcher/ResourceWatcher{TEntity}.cs

@@ -9,6 +9,7 @@
 using KubeOps.Abstractions.Controller;
 using KubeOps.Abstractions.Finalizer;
 using KubeOps.KubernetesClient;
+using KubeOps.Operator.Client;
 using KubeOps.Operator.Finalizer;
 using KubeOps.Operator.Queue;
 
@@ -36,13 +37,12 @@ internal class ResourceWatcher<TEntity> : IHostedService
     public ResourceWatcher(
         ILogger<ResourceWatcher<TEntity>> logger,
         IServiceProvider provider,
-        IKubernetesClient<TEntity> client,
         TimedEntityQueue<TEntity> queue,
         OperatorSettings settings)
     {
         _logger = logger;
         _provider = provider;
-        _client = client;
+        _client = provider.GetService<IKubernetesClient<TEntity>>() ?? KubernetesClientFactory.Create<TEntity>();
         _queue = queue;
         _settings = settings;
         _finalizers = new(() => _provider.GetServices<FinalizerRegistration>().ToList());
@@ -237,7 +237,7 @@ private async Task ReconcileFinalizer(TEntity entity)
         var pendingFinalizer = entity.Finalizers();
         if (_finalizers.Value.Find(reg =>
                 reg.EntityType == entity.GetType() && pendingFinalizer.Contains(reg.Identifier)) is not
-                { Identifier: var identifier, FinalizerType: var type })
+            { Identifier: var identifier, FinalizerType: var type })
         {
             _logger.LogDebug(
                 """Entity "{kind}/{name}" is finalizing but this operator has no registered finalizers for it.""",

test/KubeOps.Generator.Test/EntityDefinitionGenerator.Test.cs

@@ -35,7 +35,7 @@ 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::V1TestEntity>(V1TestEntity);
+                             builder.AddEntityClient<global::V1TestEntity>(V1TestEntity);
                              return builder;
                          }
                      }
@@ -60,8 +60,8 @@ public static class EntityDefinitions
                          public static readonly EntityMetadata V1AnotherEntity = new("AnotherEntity", "v1", "testing.dev", null);
                          public static IOperatorBuilder RegisterEntities(this IOperatorBuilder builder)
                          {
-                             builder.AddEntity<global::V1TestEntity>(V1TestEntity);
-                             builder.AddEntity<global::V1AnotherEntity>(V1AnotherEntity);
+                             builder.AddEntityClient<global::V1TestEntity>(V1TestEntity);
+                             builder.AddEntityClient<global::V1AnotherEntity>(V1AnotherEntity);
                              return builder;
                          }
                      }

test/KubeOps.Operator.Test/Builder/OperatorBuilder.Test.cs

@@ -42,7 +42,7 @@ public void Should_Add_Default_Resources()
     [Fact]
     public void Should_Add_Entity_Resources()
     {
-        _builder.AddEntity<V1IntegrationTestEntity>(new EntityMetadata("test", "v1", "testentities"));
+        _builder.AddEntityClient<V1IntegrationTestEntity>(new EntityMetadata("test", "v1", "testentities"));
 
         _builder.Services.Should().Contain(s =>
             s.ServiceType == typeof(IKubernetesClient<V1IntegrationTestEntity>) &&

test/KubeOps.Operator.Test/Controller/CancelEntityRequeue.Integration.Test.cs

@@ -45,7 +45,7 @@ public async Task InitializeAsync()
         await _hostBuilder.ConfigureAndStart(builder => builder.Services
             .AddSingleton(Mock)
             .AddKubernetesOperator()
-            .AddControllerWithEntity<TestController, V1IntegrationTestEntity>(meta));
+            .AddController<TestController, V1IntegrationTestEntity>());
     }
 
     public async Task DisposeAsync()