Obsolete the IDistributedApplicationLifecycleHook interface and extension methods and add a new eventing based replacement

playground/CustomResources/CustomResources.AppHost/TestResource.cs

@@ -2,14 +2,15 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Globalization;
+using Aspire.Hosting.Eventing;
 using Aspire.Hosting.Lifecycle;
 using Microsoft.Extensions.Logging;
 
 static class TestResourceExtensions
 {
     public static IResourceBuilder<TestResource> AddTestResource(this IDistributedApplicationBuilder builder, string name)
     {
-        builder.Services.TryAddLifecycleHook<TestResourceLifecycleHook>();
+        builder.Services.TryAddEventingSubscriber<TestResourceLifecycle>();
 
         var rb = builder.AddResource(new TestResource(name))
                       .WithInitialState(new()
@@ -27,13 +28,16 @@ public static IResourceBuilder<TestResource> AddTestResource(this IDistributedAp
     }
 }
 
-internal sealed class TestResourceLifecycleHook(ResourceNotificationService notificationService, ResourceLoggerService loggerService) : IDistributedApplicationLifecycleHook, IAsyncDisposable
+internal sealed class TestResourceLifecycle(
+    ResourceNotificationService notificationService,
+    ResourceLoggerService loggerService
+    ) : IDistributedApplicationEventingSubscriber
 {
     private readonly CancellationTokenSource _tokenSource = new();
 
-    public Task BeforeStartAsync(DistributedApplicationModel appModel, CancellationToken cancellationToken = default)
+    public Task OnBeforeStartAsync(BeforeStartEvent @event, CancellationToken cancellationToken = default)
     {
-        foreach (var resource in appModel.Resources.OfType<TestResource>())
+        foreach (var resource in @event.Model.Resources.OfType<TestResource>())
         {
             var states = new[] { "Starting", "Running", "Finished", "Uploading", "Downloading", "Processing", "Provisioning" };
             var stateStyles = new[] { "info", "success", "warning", "error" };
@@ -76,6 +80,12 @@ public ValueTask DisposeAsync()
         _tokenSource.Cancel();
         return default;
     }
+
+    public Task Subscribe(IDistributedApplicationEventing eventing, DistributedApplicationExecutionContext executionContext, CancellationToken cancellationToken)
+    {
+        eventing.Subscribe<BeforeStartEvent>(OnBeforeStartAsync);
+        return Task.CompletedTask;
+    }
 }
 
 sealed class TestResource(string name) : Resource(name)

playground/HealthChecks/HealthChecksSandbox.AppHost/Program.cs

@@ -1,13 +1,14 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Aspire.Hosting.Eventing;
 using Aspire.Hosting.Lifecycle;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
 
 var builder = DistributedApplication.CreateBuilder(args);
 
-builder.Services.TryAddLifecycleHook<TestResourceLifecycleHook>();
+builder.Services.TryAddEventingSubscriber<TestResourceLifecycle>();
 
 AddTestResource("healthy", HealthStatus.Healthy, "I'm fine, thanks for asking.");
 AddTestResource("unhealthy", HealthStatus.Unhealthy, "I can't do that, Dave.", exceptionMessage: "Feeling unhealthy.");
@@ -60,11 +61,11 @@ void AddTestResource(string name, HealthStatus status, string? description = nul
 
 internal sealed class TestResource(string name) : Resource(name);
 
-internal sealed class TestResourceLifecycleHook(ResourceNotificationService notificationService) : IDistributedApplicationLifecycleHook
+internal sealed class TestResourceLifecycle(ResourceNotificationService notificationService) : IDistributedApplicationEventingSubscriber
 {
-    public Task BeforeStartAsync(DistributedApplicationModel appModel, CancellationToken cancellationToken)
+    public Task OnBeforeStartAsync(BeforeStartEvent @event, CancellationToken cancellationToken)
     {
-        foreach (var resource in appModel.Resources.OfType<TestResource>())
+        foreach (var resource in @event.Model.Resources.OfType<TestResource>())
         {
             Task.Run(
                 async () =>
@@ -80,4 +81,10 @@ await notificationService.PublishUpdateAsync(
 
         return Task.CompletedTask;
     }
+
+    public Task Subscribe(IDistributedApplicationEventing eventing, DistributedApplicationExecutionContext executionContext, CancellationToken cancellationToken)
+    {
+        eventing.Subscribe<BeforeStartEvent>(OnBeforeStartAsync);
+        return Task.CompletedTask;
+    }
 }

playground/Stress/Stress.AppHost/TestResource.cs

@@ -3,14 +3,15 @@
 
 using System.Globalization;
 using Aspire.Dashboard.Model;
+using Aspire.Hosting.Eventing;
 using Aspire.Hosting.Lifecycle;
 using Microsoft.Extensions.Logging;
 
 static class TestResourceExtensions
 {
     public static IResourceBuilder<TestResource> AddTestResource(this IDistributedApplicationBuilder builder, string name)
     {
-        builder.Services.TryAddLifecycleHook<TestResourceLifecycleHook>();
+        builder.Services.TryAddEventingSubscriber<TestResourceLifecycle>();
 
         var rb = builder.AddResource(new TestResource(name))
                       .WithInitialState(new()
@@ -46,13 +47,16 @@ public static IResourceBuilder<TestNestedResource> AddNestedResource(this IDistr
     }
 }
 
-internal sealed class TestResourceLifecycleHook(ResourceNotificationService notificationService, ResourceLoggerService loggerService) : IDistributedApplicationLifecycleHook, IAsyncDisposable
+internal sealed class TestResourceLifecycle(
+    ResourceNotificationService notificationService,
+    ResourceLoggerService loggerService
+    ) : IDistributedApplicationEventingSubscriber, IAsyncDisposable
 {
     private readonly CancellationTokenSource _tokenSource = new();
 
-    public Task BeforeStartAsync(DistributedApplicationModel appModel, CancellationToken cancellationToken = default)
+    public Task OnBeforeStartAsync(BeforeStartEvent @event, CancellationToken cancellationToken = default)
     {
-        foreach (var resource in appModel.Resources.OfType<TestResource>())
+        foreach (var resource in @event.Model.Resources.OfType<TestResource>())
         {
             var states = new[] { "Starting", "Running", "Finished" };
 
@@ -94,6 +98,12 @@ public ValueTask DisposeAsync()
         _tokenSource.Cancel();
         return default;
     }
+
+    public Task Subscribe(IDistributedApplicationEventing eventing, DistributedApplicationExecutionContext executionContext, CancellationToken cancellationToken)
+    {
+        eventing.Subscribe<BeforeStartEvent>(OnBeforeStartAsync);
+        return Task.CompletedTask;
+    }
 }
 
 sealed class TestResource(string name) : Resource(name)

src/Aspire.Hosting.Azure.AppContainers/AzureContainerAppExtensions.cs

@@ -42,7 +42,7 @@ internal static IDistributedApplicationBuilder AddAzureContainerAppsInfrastructu
         // so Azure resources don't need to add the default role assignments themselves
         builder.Services.Configure<AzureProvisioningOptions>(o => o.SupportsTargetedRoleAssignments = true);
 
-        builder.Services.TryAddLifecycleHook<AzureContainerAppsInfrastructure>();
+        builder.Services.TryAddEventingSubscriber<AzureContainerAppsInfrastructure>();
 
         return builder;
     }

src/Aspire.Hosting.Azure.AppContainers/AzureContainerAppsInfrastructure.cs

@@ -5,6 +5,7 @@
 
 using Aspire.Hosting.ApplicationModel;
 using Aspire.Hosting.Azure.AppContainers;
+using Aspire.Hosting.Eventing;
 using Aspire.Hosting.Lifecycle;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
@@ -13,25 +14,19 @@ namespace Aspire.Hosting.Azure;
 
 /// <summary>
 /// Represents the infrastructure for Azure Container Apps within the Aspire Hosting environment.
-/// Implements the <see cref="IDistributedApplicationLifecycleHook"/> interface to provide lifecycle hooks for distributed applications.
 /// </summary>
 internal sealed class AzureContainerAppsInfrastructure(
     ILogger<AzureContainerAppsInfrastructure> logger,
-    IOptions<AzureProvisioningOptions> provisioningOptions,
-    DistributedApplicationExecutionContext executionContext) : IDistributedApplicationLifecycleHook
+    DistributedApplicationExecutionContext executionContext,
+    IOptions<AzureProvisioningOptions> options) : IDistributedApplicationEventingSubscriber
 {
-    public async Task BeforeStartAsync(DistributedApplicationModel appModel, CancellationToken cancellationToken = default)
+    public async Task OnBeforeStartAsync(BeforeStartEvent @event, CancellationToken cancellationToken = default)
     {
-        if (executionContext.IsRunMode)
-        {
-            return;
-        }
-
-        var caes = appModel.Resources.OfType<AzureContainerAppEnvironmentResource>().ToArray();
+        var caes = @event.Model.Resources.OfType<AzureContainerAppEnvironmentResource>().ToArray();
 
         if (caes.Length == 0)
         {
-            EnsureNoPublishAsAcaAnnotations(appModel);
+            EnsureNoPublishAsAcaAnnotations(@event.Model);
             return;
         }
 
@@ -42,9 +37,9 @@ public async Task BeforeStartAsync(DistributedApplicationModel appModel, Cancell
                 executionContext,
                 environment);
 
-            foreach (var r in appModel.GetComputeResources())
+            foreach (var r in @event.Model.GetComputeResources())
             {
-                var containerApp = await containerAppEnvironmentContext.CreateContainerAppAsync(r, provisioningOptions.Value, cancellationToken).ConfigureAwait(false);
+                var containerApp = await containerAppEnvironmentContext.CreateContainerAppAsync(r, options.Value, cancellationToken).ConfigureAwait(false);
 
                 // Capture information about the container registry used by the
                 // container app environment in the deployment target information
@@ -68,4 +63,14 @@ private static void EnsureNoPublishAsAcaAnnotations(DistributedApplicationModel
             }
         }
     }
+
+    public Task Subscribe(IDistributedApplicationEventing eventing, DistributedApplicationExecutionContext executionContext, CancellationToken cancellationToken)
+    {
+        if (!executionContext.IsRunMode)
+        {
+            eventing.Subscribe<BeforeStartEvent>(OnBeforeStartAsync);
+        }
+
+        return Task.CompletedTask;
+    }
 }

src/Aspire.Hosting.Azure.AppService/AzureAppServiceEnvironmentExtensions.cs

@@ -26,7 +26,7 @@ internal static IDistributedApplicationBuilder AddAzureAppServiceInfrastructureC
 
         builder.Services.Configure<AzureProvisioningOptions>(options => options.SupportsTargetedRoleAssignments = true);
 
-        builder.Services.TryAddLifecycleHook<AzureAppServiceInfrastructure>();
+        builder.Services.TryAddEventingSubscriber<AzureAppServiceInfrastructure>();
 
         return builder;
     }

src/Aspire.Hosting.Azure.AppService/AzureAppServiceInfrastructure.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Aspire.Hosting.ApplicationModel;
+using Aspire.Hosting.Eventing;
 using Aspire.Hosting.Lifecycle;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
@@ -11,21 +12,20 @@ namespace Aspire.Hosting.Azure.AppService;
 internal sealed class AzureAppServiceInfrastructure(
     ILogger<AzureAppServiceInfrastructure> logger,
     IOptions<AzureProvisioningOptions> provisioningOptions,
-    DistributedApplicationExecutionContext executionContext) :
-    IDistributedApplicationLifecycleHook
+    DistributedApplicationExecutionContext executionContext) : IDistributedApplicationEventingSubscriber
 {
-    public async Task BeforeStartAsync(DistributedApplicationModel appModel, CancellationToken cancellationToken = default)
+    public async Task OnBeforeStartAsync(BeforeStartEvent @event, CancellationToken cancellationToken = default)
     {
         if (!executionContext.IsPublishMode)
         {
             return;
         }
 
-        var appServiceEnvironments = appModel.Resources.OfType<AzureAppServiceEnvironmentResource>().ToArray();
+        var appServiceEnvironments = @event.Model.Resources.OfType<AzureAppServiceEnvironmentResource>().ToArray();
 
         if (appServiceEnvironments.Length == 0)
         {
-            EnsureNoPublishAsAzureAppServiceWebsiteAnnotations(appModel);
+            EnsureNoPublishAsAzureAppServiceWebsiteAnnotations(@event.Model);
             return;
         }
 
@@ -36,7 +36,7 @@ public async Task BeforeStartAsync(DistributedApplicationModel appModel, Cancell
                 executionContext,
                 appServiceEnvironment);
 
-            foreach (var resource in appModel.GetComputeResources())
+            foreach (var resource in @event.Model.GetComputeResources())
             {
                 // Support project resources and containers with Dockerfile
                 if (resource is not ProjectResource && !(resource.IsContainer() && resource.TryGetAnnotationsOfType<DockerfileBuildAnnotation>(out _)))
@@ -67,4 +67,10 @@ private static void EnsureNoPublishAsAzureAppServiceWebsiteAnnotations(Distribut
             }
         }
     }
+
+    public Task Subscribe(IDistributedApplicationEventing eventing, DistributedApplicationExecutionContext executionContext, CancellationToken cancellationToken)
+    {
+        eventing.Subscribe<BeforeStartEvent>(OnBeforeStartAsync);
+        return Task.CompletedTask;
+    }
 }