feat: Add RemoveFinalizerAsync method to finalizer manager.

docs/docs/finalizer.md

@@ -44,7 +44,7 @@ as scoped resources in DI.
 ## Register a finalizer
 
 To attach a finalizer for a resource, call the
-<xref:KubeOps.Operator.Finalizer.IFinalizerManager`1.RegisterFinalizerAsync``1(`0)>
+<xref:KubeOps.Operator.Finalizer.IFinalizerManager` 1.RegisterFinalizerAsync``1( `0)>
 method in the controller during reconciliation.
 
 ```csharp
@@ -86,3 +86,27 @@ public class TestController : IResourceController<V1TestEntity>
     }
 }
 ```
+
+## Unregistering a finalizer
+
+When a resource is finalized, the finalizer is removed automatically.
+However, if you want to remove a finalizer before a resource is deleted/finalized,
+you can use <xref:KubeOps.Operator.Finalizer.IFinalizerManager` 1.RemoveFinalizerAsync``1( `0)>.
+
+```csharp
+public class TestController : IResourceController<V1TestEntity>
+{
+    private readonly IFinalizerManager<V1TestEntity> _manager;
+
+    public TestController(IFinalizerManager<V1TestEntity> manager)
+    {
+        _manager = manager;
+    }
+
+    public async Task<ResourceControllerResult> CreatedAsync(V1TestEntity resource)
+    {
+        await _manager.RemoveFinalizerAsync<MyFinalizer>(resource);
+        return null;
+    }
+}
+```

src/KubeOps/Operator/Finalizer/FinalizerManager{TEntity}.cs

@@ -25,13 +25,9 @@ internal class FinalizerManager<TEntity> : IFinalizerManager<TEntity>
             _finalizerInstanceBuilder = finalizerInstanceBuilder;
         }
 
-        public async Task RegisterFinalizerAsync<TFinalizer>(TEntity entity)
+        public Task RegisterFinalizerAsync<TFinalizer>(TEntity entity)
             where TFinalizer : IResourceFinalizer<TEntity>
-        {
-            var finalizer = _finalizerInstanceBuilder.BuildFinalizer<TEntity, TFinalizer>();
-
-            await RegisterFinalizerInternalAsync(entity, finalizer);
-        }
+            => RegisterFinalizerInternalAsync(entity, _finalizerInstanceBuilder.BuildFinalizer<TEntity, TFinalizer>());
 
         public async Task RegisterAllFinalizersAsync(TEntity entity)
         {
@@ -40,6 +36,28 @@ public async Task RegisterAllFinalizersAsync(TEntity entity)
                     .Select(f => RegisterFinalizerInternalAsync(entity, f)));
         }
 
+        public async Task RemoveFinalizerAsync<TFinalizer>(TEntity entity)
+            where TFinalizer : IResourceFinalizer<TEntity>
+        {
+            var finalizer = _finalizerInstanceBuilder.BuildFinalizer<TEntity, TFinalizer>();
+
+            _logger.LogTrace(
+                @"Try to add finalizer ""{finalizer}"" on entity ""{kind}/{name}"".",
+                finalizer.Identifier,
+                entity.Kind,
+                entity.Name());
+
+            if (entity.RemoveFinalizer(finalizer.Identifier))
+            {
+                _logger.LogInformation(
+                    @"Removed finalizer ""{finalizer}"" on entity ""{kind}/{name}"".",
+                    finalizer.Identifier,
+                    entity.Kind,
+                    entity.Name());
+                await _client.Update(entity);
+            }
+        }
+
         async Task IFinalizerManager<TEntity>.FinalizeAsync(TEntity entity)
         {
             var semaphore = new SemaphoreSlim(1);

src/KubeOps/Operator/Finalizer/IFinalizerManager{TEntity}.cs

@@ -12,7 +12,7 @@ public interface IFinalizerManager<TEntity>
         where TEntity : IKubernetesObject<V1ObjectMeta>
     {
         /// <summary>
-        /// Register a finalizer for the entity type on the provided instance.
+        /// Register a <see cref="IResourceFinalizer{TEntity}"/> for the entity type on the provided instance.
         /// </summary>
         /// <param name="entity">The entity that will receive the finalizer.</param>
         /// <typeparam name="TFinalizer">The type of the finalizer.</typeparam>
@@ -21,12 +21,22 @@ Task RegisterFinalizerAsync<TFinalizer>(TEntity entity)
             where TFinalizer : IResourceFinalizer<TEntity>;
 
         /// <summary>
-        /// Register all known finalizers for the entity type on the provided instance.
+        /// Register all known <see cref="IResourceFinalizer{TEntity}"/> for the entity type on the provided instance.
         /// </summary>
         /// <param name="entity">The entity that will receive the finalizers.</param>
         /// <returns>A task when the operation is done.</returns>
         Task RegisterAllFinalizersAsync(TEntity entity);
 
+        /// <summary>
+        /// Remove a given <see cref="IResourceFinalizer{TEntity}"/> from an entity, if
+        /// it is registered.
+        /// </summary>
+        /// <param name="entity">The entity that should have the finalizer removed.</param>
+        /// <typeparam name="TFinalizer">The type of the finalizer.</typeparam>
+        /// <returns>A task when the operation is done.</returns>
+        Task RemoveFinalizerAsync<TFinalizer>(TEntity entity)
+            where TFinalizer : IResourceFinalizer<TEntity>;
+
         internal Task FinalizeAsync(TEntity entity);
     }
 }