dotnet · maddymontaquila · Jul 29, 2025 · Jul 3, 2025 · Jul 4, 2025 · Jul 4, 2025
@@ -7,6 +7,10 @@ Write for readers who may have a limited vocabulary or are not native English sp
 - Use active voice
 - Use the second person (you, your) to address the reader directly
 
+## Lists
+
+Use lists more sparingly. Use them only when they help to clarify the content. Use bullet points for unordered lists and numbered lists for ordered lists. Regardless of the type of list, always use sentence-style capitalization, complete sentences, and proper punctuation.
+
 ## Headings
 
 Headings use sentence-style capitalization. Always capitalize the first word of a heading. Do not use gerunds (e.g., "Using" or "Creating") in heading.

@@ -1,5 +1,8 @@
 syntax: glob
 
+.aspire/
+**/.aspire/
+
 # Python virtual environments
 .venv
 

@@ -55,6 +55,7 @@ For more information, see [.NET Aspire and launch profiles](../fundamentals/laun
 |--|--|--|
 | `ASPIRE_ALLOW_UNSECURED_TRANSPORT` | `false` | Allows communication with the app host without https. `ASPNETCORE_URLS` (dashboard address) and `ASPIRE_RESOURCE_SERVICE_ENDPOINT_URL` (app host resource service address) must be secured with HTTPS unless true. |
 | `ASPIRE_CONTAINER_RUNTIME` | `docker` | Allows the user of alternative container runtimes for resources backed by containers. Possible values are `docker` (default) or `podman`. See [Setup and tooling overview for more details](../fundamentals/setup-tooling.md).  |
+| `ASPIRE_VERSION_CHECK_DISABLED` | `false` | When set to `true`, .NET Aspire doesn't check for newer versions on startup. |
 
 ## Resource service
 

@@ -1,7 +1,7 @@
 ---
 title: Eventing in .NET Aspire
 description: Learn how to use the .NET eventing features with .NET Aspire.
-ms.date: 04/04/2025
+ms.date: 07/10/2025
 ---
 
 # Eventing in .NET Aspire
@@ -17,48 +17,55 @@ In this article, you learn how to use the eventing features in .NET Aspire.
 The following events are available in the app host and occur in the following order:
 
 1. <xref:Aspire.Hosting.ApplicationModel.BeforeStartEvent>: This event is raised before the app host starts.
-1. <xref:Aspire.Hosting.ApplicationModel.AfterEndpointsAllocatedEvent>: This event is raised after the app host allocated endpoints.
+1. <xref:Aspire.Hosting.ApplicationModel.ResourceEndpointsAllocatedEvent>: This event is raised per resource after its endpoints are allocated.
 1. <xref:Aspire.Hosting.ApplicationModel.AfterResourcesCreatedEvent>: This event is raised after the app host created resources.
 
 All of the preceding events are analogous to the [app host life cycles](xref:dotnet/aspire/app-host#app-host-life-cycles). That is, an implementation of the <xref:Aspire.Hosting.Lifecycle.IDistributedApplicationLifecycleHook> could handle these events just the same. With the eventing API, however, you can run arbitrary code when these events are raised and event define custom events—any event that implements the <xref:Aspire.Hosting.Eventing.IDistributedApplicationEvent> interface.
 
 ### Subscribe to app host events
 
-To subscribe to the built-in app host events, use the eventing API. After you have a distributed application builder instance, walk up to the <xref:Aspire.Hosting.IDistributedApplicationBuilder.Eventing?displayProperty=nameWithType> property and call the <xref:Aspire.Hosting.Eventing.IDistributedApplicationEventing.Subscribe``1(System.Func{``0,System.Threading.CancellationToken,System.Threading.Tasks.Task})> API. Consider the following sample app host _Program.cs_ file:
+To subscribe to the built-in app host events, use the eventing API. After you have a distributed application builder instance, walk up to the <xref:Aspire.Hosting.IDistributedApplicationBuilder.Eventing?displayProperty=nameWithType> property and call the <xref:Aspire.Hosting.Eventing.IDistributedApplicationEventing.Subscribe``1(System.Func{``0,System.Threading.CancellationToken,System.Threading.Tasks.Task})> API. Consider the following sample app host _AppHost.cs_ file:
 
-:::code source="snippets/AspireApp/AspireApp.AppHost/Program.cs":::
+:::code source="snippets/AspireApp/AspireApp.AppHost/AppHost.cs":::
 
 The preceding code is based on the starter template with the addition of the calls to the `Subscribe` API. The `Subscribe<T>` API returns a <xref:Aspire.Hosting.Eventing.DistributedApplicationEventSubscription> instance that you can use to unsubscribe from the event. It's common to discard the returned subscriptions, as you don't usually need to unsubscribe from events as the entire app is torn down when the app host is shut down.
 
 When the app host is run, by the time the .NET Aspire dashboard is displayed, you should see the following log output in the console:
 
-:::code language="Plaintext" source="snippets/AspireApp/AspireApp.AppHost/Console.txt" highlight="2,10-14,20":::
+:::code language="Plaintext" source="snippets/AspireApp/AspireApp.AppHost/Console.txt" highlight="2,10,12,14,16,22":::
 
-The log output confirms that event handlers are executed in the order of the app host life cycle events. The subscription order doesn't affect execution order. The `BeforeStartEvent` is triggered first, followed by `AfterEndpointsAllocatedEvent`, then each resource has its `ResourceEndpointsAllocatedEvent` event fired, and finally `AfterResourcesCreatedEvent`.
+The log output confirms that event handlers are executed in the order of the app host life cycle events. The subscription order doesn't affect execution order. The `BeforeStartEvent` is triggered first, followed by each resource's `ResourceEndpointsAllocatedEvent`, and finally `AfterResourcesCreatedEvent`.
 
 ## Resource eventing
 
 In addition to the app host events, you can also subscribe to resource events. Resource events are raised specific to an individual resource. Resource events are defined as implementations of the <xref:Aspire.Hosting.Eventing.IDistributedApplicationResourceEvent> interface. The following resource events are available in the listed order:
 
-1. `InitializeResourceEvent`: Raised by orchestrators to signal to resources that they should initialize themselves.
+1. <xref:Aspire.Hosting.ApplicationModel.InitializeResourceEvent>: Raised by orchestrators to signal to resources that they should initialize themselves.
+1. <xref:Aspire.Hosting.ApplicationModel.ResourceEndpointsAllocatedEvent>: Raised when the orchestrator allocates endpoints for a resource.
 1. <xref:Aspire.Hosting.ApplicationModel.ConnectionStringAvailableEvent>: Raised when a connection string becomes available for a resource.
 1. <xref:Aspire.Hosting.ApplicationModel.BeforeResourceStartedEvent>: Raised before the orchestrator starts a new resource.
 1. <xref:Aspire.Hosting.ApplicationModel.ResourceReadyEvent>: Raised when a resource initially transitions to a ready state.
 
 ### Subscribe to resource events
 
-To subscribe to resource events, use the eventing API. After you have a distributed application builder instance, walk up to the <xref:Aspire.Hosting.IDistributedApplicationBuilder.Eventing?displayProperty=nameWithType> property and call the <xref:Aspire.Hosting.Eventing.IDistributedApplicationEventing.Subscribe``1(Aspire.Hosting.ApplicationModel.IResource,System.Func{``0,System.Threading.CancellationToken,System.Threading.Tasks.Task})> API. Consider the following sample app host _Program.cs_ file:
+To subscribe to resource events, use the convenience-based extension methods—`On*`. After you have a distributed application builder instance, and a resource builder, walk up to the instance and chain a call to the desired `On*` event API. Consider the following sample _AppHost.cs_ file:
 
-:::code source="snippets/AspireApp/AspireApp.ResourceAppHost/Program.cs":::
+:::code source="snippets/AspireApp/AspireApp.ResourceAppHost/AppHost.cs":::
 
-The preceding code subscribes to the `InitializeResourceEvent`, `ResourceReadyEvent`, `ConnectionStringAvailableEvent`, and `BeforeResourceStartedEvent` events on the `cache` resource. When <xref:Aspire.Hosting.RedisBuilderExtensions.AddRedis*> is called, it returns an <xref:Aspire.Hosting.ApplicationModel.IResourceBuilder`1> where `T` is a <xref:Aspire.Hosting.ApplicationModel.RedisResource>. The resource builder exposes the resource as the <xref:Aspire.Hosting.ApplicationModel.IResourceBuilder`1.Resource?displayProperty=nameWithType> property. The resource in question is then passed to the `Subscribe` API to subscribe to the events on the resource.
+The preceding code subscribes to the `InitializeResourceEvent`, `ResourceReadyEvent`, `ResourceEndpointsAllocatedEvent`, `ConnectionStringAvailableEvent`, and `BeforeResourceStartedEvent` events on the `cache` resource. When <xref:Aspire.Hosting.RedisBuilderExtensions.AddRedis*> is called, it returns an <xref:Aspire.Hosting.ApplicationModel.IResourceBuilder`1> where `T` is a <xref:Aspire.Hosting.ApplicationModel.RedisResource>. Chain calls to the `On*` methods to subscribe to the events. The `On*` methods return the same <xref:Aspire.Hosting.ApplicationModel.IResourceBuilder`1> instance, so you can chain multiple calls:
+
+- `OnInitializeResource`: Subscribes to the <xref:Aspire.Hosting.ApplicationModel.InitializeResourceEvent>.
+- `OnResourceEndpointsAllocated`: Subscribes to the <xref:Aspire.Hosting.ApplicationModel.ResourceEndpointsAllocatedEvent> event.
+- `OnConnectionStringAvailable`: Subscribes to the <xref:Aspire.Hosting.ApplicationModel.ConnectionStringAvailableEvent> event.
+- `OnBeforeResourceStarted`: Subscribes to the <xref:Aspire.Hosting.ApplicationModel.BeforeResourceStartedEvent> event.
+- `OnResourceReady`: Subscribes to the <xref:Aspire.Hosting.ApplicationModel.ResourceReadyEvent> event.
 
 When the app host is run, by the time the .NET Aspire dashboard is displayed, you should see the following log output in the console:
 
-:::code language="Plaintext" source="snippets/AspireApp/AspireApp.ResourceAppHost/Console.txt" highlight="8,10,12,18":::
+:::code language="Plaintext" source="snippets/AspireApp/AspireApp.ResourceAppHost/Console.txt" highlight="8,10,12,14,20":::
 
 > [!NOTE]
-> Some events are blocking. For example, when the `BeforeResourceStartEvent` is published, the startup of the resource will be blocked until all subscriptions for that event on a given resource have completed executing. Whether an event is blocking or not depends on how it is published (see the following section).
+> Some events block execution. For example, when the `BeforeResourceStartedEvent` is published, the resource startup blocks until all subscriptions for that event on a given resource finish executing. Whether an event blocks or not depends on how you publish it (see the following section).
 
 ## Publish events
 
@@ -74,15 +81,15 @@ Then, you can subscribe and publish the event by calling the either of the follo
 When events are dispatched, you can control how the events are dispatched to subscribers. The event dispatch behavior is specified with the `EventDispatchBehavior` enum. The following behaviors are available:
 
 - <xref:Aspire.Hosting.Eventing.EventDispatchBehavior.BlockingSequential?displayProperty=nameWithType>: Fires events sequentially and blocks until they're all processed.
-- <xref:Aspire.Hosting.Eventing.EventDispatchBehavior.BlockingConcurrent?displayProperty=nameWithType>: Fires events concurrently and blocks until they are all processed.
+- <xref:Aspire.Hosting.Eventing.EventDispatchBehavior.BlockingConcurrent?displayProperty=nameWithType>: Fires events concurrently and blocks until they're all processed.
 - <xref:Aspire.Hosting.Eventing.EventDispatchBehavior.NonBlockingSequential?displayProperty=nameWithType>: Fires events sequentially but doesn't block.
 - <xref:Aspire.Hosting.Eventing.EventDispatchBehavior.NonBlockingConcurrent?displayProperty=nameWithType>: Fires events concurrently but doesn't block.
 
 The default behavior is `EventDispatchBehavior.BlockingSequential`. To override this behavior, when calling a publishing API such as <xref:Aspire.Hosting.Eventing.IDistributedApplicationEventing.PublishAsync*>, provide the desired behavior as an argument.
 
 ## App Host life cycle events
 
-As you have seen, eventing is the most flexible approach. However, in this section you learn about the alternative: life cycle events.
+Eventing offers the most flexibility. However, this section explains the alternative: life cycle events.
 
 The .NET Aspire app host exposes several life cycles that you can hook into by implementing the <xref:Aspire.Hosting.Lifecycle.IDistributedApplicationLifecycleHook> interface. The following lifecycle methods are available:
 
@@ -96,7 +103,7 @@ The .NET Aspire app host exposes several life cycles that you can hook into by i
 
 To register a life cycle hook, implement the <xref:Aspire.Hosting.Lifecycle.IDistributedApplicationLifecycleHook> interface and register the hook with the app host using the <xref:Aspire.Hosting.Lifecycle.LifecycleHookServiceCollectionExtensions.AddLifecycleHook*> API:
 
-:::code source="../fundamentals/snippets/lifecycles/AspireApp/AspireApp.AppHost/Program.cs":::
+:::code source="../fundamentals/snippets/lifecycles/AspireApp/AspireApp.AppHost/AppHost.cs":::
 
 The preceding code:
 

@@ -15,32 +15,21 @@
     .WaitFor(apiService);
 
 builder.Eventing.Subscribe<ResourceEndpointsAllocatedEvent>(
-    (@event, cancellationToken) =>
-    {
-        // The event doesn't expose an IServiceProvider, just write to the console.
-        Console.WriteLine($"""
-                    3. '{@event.Resource.Name}' ResourceEndpointsAllocatedEvent
-            """);
-
-        return Task.CompletedTask;
-    });
-
-builder.Eventing.Subscribe<BeforeStartEvent>(
     static (@event, cancellationToken) =>
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("1. BeforeStartEvent");
+        logger.LogInformation("2. \"{ResourceName}\" ResourceEndpointsAllocatedEvent", @event.Resource.Name);
 
         return Task.CompletedTask;
     });
 
-builder.Eventing.Subscribe<AfterEndpointsAllocatedEvent>(
+builder.Eventing.Subscribe<BeforeStartEvent>(
     static (@event, cancellationToken) =>
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("2. AfterEndpointsAllocatedEvent");
+        logger.LogInformation("1. BeforeStartEvent");
 
         return Task.CompletedTask;
     });
@@ -50,7 +39,7 @@
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("4. AfterResourcesCreatedEvent");
+        logger.LogInformation("3. AfterResourcesCreatedEvent");
 
         return Task.CompletedTask;
     });

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <Sdk Name="Aspire.AppHost.Sdk" Version="9.2.0" />
+  <Sdk Name="Aspire.AppHost.Sdk" Version="9.4.0" />
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -16,8 +16,8 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Aspire.Hosting.AppHost" Version="9.3.1" />
-    <PackageReference Include="Aspire.Hosting.Redis" Version="9.3.1" />
+    <PackageReference Include="Aspire.Hosting.AppHost" Version="9.4.0" />
+    <PackageReference Include="Aspire.Hosting.Redis" Version="9.4.0" />
   </ItemGroup>
 
 </Project>
@@ -1,22 +1,24 @@
 info: Program[0]
       1. BeforeStartEvent
 info: Aspire.Hosting.DistributedApplication[0]
-      Aspire version: 9.3.0-preview.1.25262.2+6d54dc081cd2e7ea435e33f7c0e62ff6946ae66d
+      Aspire version: 9.4.0
 info: Aspire.Hosting.DistributedApplication[0]
       Distributed application starting.
 info: Aspire.Hosting.DistributedApplication[0]
       Application host directory is: ../AspireApp/AspireApp.AppHost
 info: Program[0]
-      2. AfterEndpointsAllocatedEvent
-        3. 'aspire-dashboard' ResourceEndpointsAllocatedEvent
-        3. 'cache' ResourceEndpointsAllocatedEvent
-        3. 'apiservice' ResourceEndpointsAllocatedEvent
-        3. 'webfrontend' ResourceEndpointsAllocatedEvent
+      2. "cache" ResourceEndpointsAllocatedEvent
+info: Program[0]
+      2. "apiservice" ResourceEndpointsAllocatedEvent
+info: Program[0]
+      2. "webfrontend" ResourceEndpointsAllocatedEvent
+info: Program[0]
+      2. "aspire-dashboard" ResourceEndpointsAllocatedEvent
 info: Aspire.Hosting.DistributedApplication[0]
       Now listening on: https://localhost:17178
 info: Aspire.Hosting.DistributedApplication[0]
       Login to the dashboard at https://localhost:17178/login?t=<YOUR_TOKEN>
 info: Program[0]
-      4. AfterResourcesCreatedEvent
+      3. AfterResourcesCreatedEvent
 info: Aspire.Hosting.DistributedApplication[0]
       Distributed application started. Press Ctrl+C to shut down.
@@ -5,45 +5,52 @@
 
 var cache = builder.AddRedis("cache");
 
-builder.Eventing.Subscribe<ResourceReadyEvent>(
-    cache.Resource,
-    static (@event, cancellationToken) =>
+cache.OnResourceReady(static (resource, @event, cancellationToken) =>
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("4. ResourceReadyEvent");
+        logger.LogInformation("5. OnResourceReady");
 
         return Task.CompletedTask;
     });
 
-builder.Eventing.Subscribe<InitializeResourceEvent>(cache.Resource,
-    static (@event, cancellationToken) =>
+cache.OnInitializeResource(
+    static (resource, @event, cancellationToken) =>
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("1. InitializeResourceEvent");
+        logger.LogInformation("1. OnInitializeResource");
 
         return Task.CompletedTask;
     });
 
-builder.Eventing.Subscribe<BeforeResourceStartedEvent>(
-    cache.Resource,
-    static (@event, cancellationToken) =>
+cache.OnBeforeResourceStarted(
+    static (resource, @event, cancellationToken) =>
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("3. BeforeResourceStartedEvent");
+        logger.LogInformation("4. OnBeforeResourceStarted");
+
+
+        return Task.CompletedTask;
+    });
+
+cache.OnResourceEndpointsAllocated(
+    static (resource, @event, cancellationToken) =>
+    {
+        var logger = @event.Services.GetRequiredService<ILogger<Program>>();
+
+        logger.LogInformation("2. OnResourceEndpointsAllocated");
 
         return Task.CompletedTask;
     });
 
-builder.Eventing.Subscribe<ConnectionStringAvailableEvent>(
-    cache.Resource,
-    static (@event, cancellationToken) =>
+cache.OnConnectionStringAvailable(
+    static (resource, @event, cancellationToken) =>
     {
         var logger = @event.Services.GetRequiredService<ILogger<Program>>();
 
-        logger.LogInformation("2. ConnectionStringAvailableEvent");
+        logger.LogInformation("3. OnConnectionStringAvailable");
 
         return Task.CompletedTask;
     });

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <Sdk Name="Aspire.AppHost.Sdk" Version="9.2.0" />
+  <Sdk Name="Aspire.AppHost.Sdk" Version="9.4.0" />
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
@@ -16,8 +16,8 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Aspire.Hosting.AppHost" Version="9.3.1" />
-    <PackageReference Include="Aspire.Hosting.Redis" Version="9.3.1" />
+    <PackageReference Include="Aspire.Hosting.AppHost" Version="9.4.0" />
+    <PackageReference Include="Aspire.Hosting.Redis" Version="9.4.0" />
   </ItemGroup>
 
 </Project>