Make container runtime health check conditional based on resource requirements

src/Aspire.Hosting/Publishing/ResourceContainerImageBuilder.cs

@@ -134,32 +134,33 @@ public async Task BuildImagesAsync(IEnumerable<IResource> resources, ContainerBu
 
         await using (step.ConfigureAwait(false))
         {
-            // Currently, we build these images to the local Docker daemon. We need to ensure that
-            // the Docker daemon is running and accessible
-
-            var task = await step.CreateTaskAsync(
-                $"Checking {ContainerRuntime.Name} health",
-                cancellationToken).ConfigureAwait(false);
-
-            await using (task.ConfigureAwait(false))
+            // Only check container runtime health if there are resources that need it
+            if (ResourcesRequireContainerRuntime(resources, options))
             {
-                var containerRuntimeHealthy = await ContainerRuntime.CheckIfRunningAsync(cancellationToken).ConfigureAwait(false);
+                var task = await step.CreateTaskAsync(
+                    $"Checking {ContainerRuntime.Name} health",
+                    cancellationToken).ConfigureAwait(false);
 
-                if (!containerRuntimeHealthy)
+                await using (task.ConfigureAwait(false))
                 {
-                    logger.LogError("Container runtime is not running or is unhealthy. Cannot build container images.");
+                    var containerRuntimeHealthy = await ContainerRuntime.CheckIfRunningAsync(cancellationToken).ConfigureAwait(false);
 
-                    await task.FailAsync(
-                        $"{ContainerRuntime.Name} is not running or is unhealthy.",
-                        cancellationToken).ConfigureAwait(false);
+                    if (!containerRuntimeHealthy)
+                    {
+                        logger.LogError("Container runtime is not running or is unhealthy. Cannot build container images.");
 
-                    await step.CompleteAsync("Building container images failed", CompletionState.CompletedWithError, cancellationToken).ConfigureAwait(false);
-                    throw new InvalidOperationException("Container runtime is not running or is unhealthy.");
-                }
+                        await task.FailAsync(
+                            $"{ContainerRuntime.Name} is not running or is unhealthy.",
+                            cancellationToken).ConfigureAwait(false);
 
-                await task.SucceedAsync(
-                    $"{ContainerRuntime.Name} is healthy.",
-                    cancellationToken).ConfigureAwait(false);
+                        await step.CompleteAsync("Building container images failed", CompletionState.CompletedWithError, cancellationToken).ConfigureAwait(false);
+                        throw new InvalidOperationException("Container runtime is not running or is unhealthy.");
+                    }
+
+                    await task.SucceedAsync(
+                        $"{ContainerRuntime.Name} is healthy.",
+                        cancellationToken).ConfigureAwait(false);
+                }
             }
 
             foreach (var resource in resources)
@@ -386,6 +387,17 @@ await ContainerRuntime.BuildImageAsync(
         return await step.CreateTaskAsync(description, cancellationToken).ConfigureAwait(false);
     }
 
+    // .NET Container builds that push OCI images to a local file path do not need a runtime
+    internal static bool ResourcesRequireContainerRuntime(IEnumerable<IResource> resources, ContainerBuildOptions? options)
+    {
+        var hasDockerfileResources = resources.Any(resource =>
+            resource.TryGetLastAnnotation<ContainerImageAnnotation>(out _) &&
+            resource.TryGetLastAnnotation<DockerfileBuildAnnotation>(out _));
+        var usesDocker = options == null || options.ImageFormat == ContainerImageFormat.Docker;
+        var hasNoOutputPath = options?.OutputPath == null;
+        return hasDockerfileResources || usesDocker || hasNoOutputPath;
+    }
+
 }
 
 /// <summary>

tests/Aspire.Hosting.Tests/Publishing/ResourceContainerImageBuilderTests.cs

@@ -382,6 +382,66 @@ public void ContainerBuildOptions_CanSetAllProperties()
         Assert.Equal(ContainerTargetPlatform.LinuxArm64, options.TargetPlatform);
     }
 
+    [Fact]
+    public async Task BuildImagesAsync_WithOnlyProjectResourcesAndOci_DoesNotNeedContainerRuntime()
+    {
+        using var builder = TestDistributedApplicationBuilder.Create(output);
+
+        builder.Services.AddLogging(logging =>
+        {
+            logging.AddFakeLogging();
+            logging.AddXunit(output);
+        });
+
+        // Create a fake container runtime that would fail if called
+        var fakeContainerRuntime = new FakeContainerRuntime(shouldFail: true);
+        builder.Services.AddKeyedSingleton<IContainerRuntime>("docker", fakeContainerRuntime);
+
+        var servicea = builder.AddProject<Projects.ServiceA>("servicea");
+
+        using var app = builder.Build();
+
+        using var cts = new CancellationTokenSource(TestConstants.LongTimeoutTimeSpan);
+        var imageBuilder = app.Services.GetRequiredService<IResourceContainerImageBuilder>();
+
+        // This should not fail despite the fake container runtime being configured to fail
+        // because we only have project resources (no DockerfileBuildAnnotation)
+        var options = new ContainerBuildOptions { ImageFormat = ContainerImageFormat.Oci, OutputPath = "/tmp/test-path" };
+        await imageBuilder.BuildImagesAsync([servicea.Resource], options: options, cts.Token);
+
+        // Validate that the container runtime health check was not called
+        Assert.False(fakeContainerRuntime.WasHealthCheckCalled);
+    }
+
+    [Fact]
+    public async Task BuildImagesAsync_WithDockerfileResources_ChecksContainerRuntimeHealth()
+    {
+        using var builder = TestDistributedApplicationBuilder.Create(output);
+
+        builder.Services.AddLogging(logging =>
+        {
+            logging.AddFakeLogging();
+            logging.AddXunit(output);
+        });
+
+        // Create a fake container runtime that tracks health check calls
+        var fakeContainerRuntime = new FakeContainerRuntime(shouldFail: false);
+        builder.Services.AddKeyedSingleton<IContainerRuntime>("docker", fakeContainerRuntime);
+
+        var (tempContextPath, tempDockerfilePath) = await DockerfileUtils.CreateTemporaryDockerfileAsync();
+        var dockerfileResource = builder.AddDockerfile("test-dockerfile", tempContextPath, tempDockerfilePath);
+
+        using var app = builder.Build();
+
+        using var cts = new CancellationTokenSource(TestConstants.LongTimeoutTimeSpan);
+        var imageBuilder = app.Services.GetRequiredService<IResourceContainerImageBuilder>();
+
+        await imageBuilder.BuildImagesAsync([dockerfileResource.Resource], options: null, cts.Token);
+
+        // Validate that the container runtime health check was called for resources with DockerfileBuildAnnotation
+        Assert.True(fakeContainerRuntime.WasHealthCheckCalled);
+    }
+
     [Fact]
     public async Task BuildImageAsync_ThrowsInvalidOperationException_WhenDockerRuntimeNotAvailable()
     {
@@ -393,7 +453,7 @@ public async Task BuildImageAsync_ThrowsInvalidOperationException_WhenDockerRunt
             logging.AddXunit(output);
         });
 
-        builder.Services.AddKeyedSingleton<IContainerRuntime>("docker", new UnhealthyMockContainerRuntime());
+        builder.Services.AddKeyedSingleton<IContainerRuntime>("docker", new FakeContainerRuntime(shouldFail: true));
 
         var (tempContextPath, tempDockerfilePath) = await DockerfileUtils.CreateTemporaryDockerfileAsync();
         var container = builder.AddDockerfile("container", tempContextPath, tempDockerfilePath);
@@ -414,18 +474,21 @@ public async Task BuildImageAsync_ThrowsInvalidOperationException_WhenDockerRunt
         Assert.Contains(logs, log => log.Message.Contains("Container runtime is not running or is unhealthy. Cannot build container images."));
     }
 
-    private sealed class UnhealthyMockContainerRuntime : IContainerRuntime
+    private sealed class FakeContainerRuntime(bool shouldFail) : IContainerRuntime
     {
-        public string Name => "MockDocker";
+        public string Name => "fake-runtime";
+        public bool WasHealthCheckCalled { get; private set; }
 
         public Task<bool> CheckIfRunningAsync(CancellationToken cancellationToken)
         {
-            return Task.FromResult(false);
+            WasHealthCheckCalled = true;
+            return Task.FromResult(!shouldFail);
         }
 
         public Task BuildImageAsync(string contextPath, string dockerfilePath, string imageName, ContainerBuildOptions? options, CancellationToken cancellationToken)
         {
-            throw new InvalidOperationException("This mock runtime should not be used for building images.");
+            // For testing, we don't need to actually build anything
+            return Task.CompletedTask;
         }
     }
 }