Fix permission denied error in Azure Pipelines

src/Aspire.Hosting/ApplicationModel/ProjectResource.cs

@@ -163,10 +163,13 @@ private async Task BuildProjectImage(PipelineStepContext ctx)
         // Add COPY --from: statements for each source
         stage.AddContainerFiles(this, containerWorkingDir, logger);
 
-        // Get the directory service to create temp Dockerfile
         var projectDir = Path.GetDirectoryName(projectMetadata.ProjectPath)!;
+
+        // Create a unique temporary Dockerfile path for this resource using the directory service.
+        // Passing a file name causes CreateTempFile to create the file in a new, empty subdirectory,
+        // which avoids Docker/buildx scanning the entire temporary directory.
         var directoryService = ctx.Services.GetRequiredService<IFileSystemService>();
-        var tempDockerfilePath = directoryService.TempDirectory.CreateTempFile().Path;
+        var tempDockerfilePath = directoryService.TempDirectory.CreateTempFile("Dockerfile").Path;
 
         var builtSuccessfully = false;
         try

src/Aspire.Hosting/ContainerResourceBuilderExtensions.cs

@@ -718,9 +718,11 @@ public static IResourceBuilder<T> WithDockerfileFactory<T>(this IResourceBuilder
         var fullyQualifiedContextPath = Path.GetFullPath(contextPath, builder.ApplicationBuilder.AppHostDirectory)
                                            .TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
 
-        // Create a unique temporary Dockerfile path for this resource using the directory service
+        // Create a unique temporary Dockerfile path for this resource using the directory service.
+        // Passing a file name causes CreateTempFile to create the file in a new, empty subdirectory,
+        // which avoids Docker/buildx scanning the entire temporary directory.
         var directoryService = builder.ApplicationBuilder.FileSystemService;
-        var tempDockerfilePath = directoryService.TempDirectory.CreateTempFile().Path;
+        var tempDockerfilePath = directoryService.TempDirectory.CreateTempFile("Dockerfile").Path;
 
         var imageName = ImageNameGenerator.GenerateImageName(builder);
         var imageTag = ImageNameGenerator.GenerateImageTag(builder);