public override async Task <object?> ExecuteAsync()
        {
            if (callbacks.Count == 0)
            {
                return(Task.FromResult <object?>(null));
            }

            if (callbacks.Count > 1)
            {
                throw new InvalidOperationException("More than one application type is not supported.");
            }

            var kvp = callbacks.Single();

            var type      = kvp.Key;
            var delegates = kvp.Value;

            output.WriteDebugLine($"Creating instance of application type '{type}'.");
            var application = Activator.CreateInstance(type);

            output.WriteDebugLine($"Done creating instance of application type '{type}'.");

            var wrapper = new ApplicationWrapper(application !, rootDirectory);

            wrapper.Globals.Name ??= name;

            foreach (var service in wrapper.Services)
            {
                output.WriteDebugLine($"Found service '{service.FriendlyName} {{ Name: {service.Service.Name} }}'.");

                string?projectRelativeFilePath = null;
                string?projectFilePath         = null;
                if (solution != null)
                {
                    var project = FindProjectInSolution(solution, service.FriendlyName);
                    if (project == null)
                    {
                        output.WriteDebugLine($"Could not find project for service '{service.FriendlyName}'.");
                        continue;
                    }

                    output.WriteDebugLine($"Found project '{project.RelativePath}' for service '{service.FriendlyName}'.");
                    projectRelativeFilePath = project.RelativePath.Replace('\\', Path.DirectorySeparatorChar);
                    projectFilePath         = project.AbsolutePath.Replace('\\', Path.DirectorySeparatorChar);
                }
                else if (projectFile != null)
                {
                    var normalized = Names.NormalizeToFriendly(Path.GetFileNameWithoutExtension(projectFile.Name));
                    if (!string.Equals(normalized, service.FriendlyName))
                    {
                        output.WriteDebugLine($"Skipping service '{service.FriendlyName}'.");
                        continue;
                    }

                    projectRelativeFilePath = projectFile.FullName;
                    projectFilePath         = projectFile.FullName;
                }

                if (projectFilePath != null)
                {
                    var project = new Project(projectRelativeFilePath !);
                    await ProjectReader.ReadProjectDetailsAsync(output, new FileInfo(projectFilePath), project);

                    service.Service.Source = project;

                    // Apply defaults to everything that has a project.
                    var container = new ContainerInfo();
                    service.Service.GeneratedAssets.Container = container;
                    DockerfileGenerator.ApplyContainerDefaults(wrapper, service, project, container);
                }
            }

            output.WriteDebugLine($"Running {delegates.Count} customization callbacks.");
            for (var i = 0; i < delegates.Count; i++)
            {
                delegates[i].DynamicInvoke(application);
            }
            output.WriteDebugLine($"Done running {delegates.Count} customization callbacks.");


            return(application);
        }
        private static async Task ExecuteAsync(OutputContext output, FileInfo projectFile, List <string> outputs, bool force)
        {
            var config = await OpulenceConfigFactory.ReadConfigAsync(output, projectFile.DirectoryName);

            if (config == null)
            {
                // Allow operating without config for now.
                output.WriteInfoLine("config was not found, using defaults");
                config = new OpulenceConfig()
                {
                    Container = new ContainerConfig()
                    {
                        Registry = new RegistryConfig(),
                    }
                };
            }

            var application = ApplicationFactory.CreateDefault(config, projectFile);
            await ProjectReader.InitializeAsync(output, application);

            await ScriptRunner.RunProjectScriptAsync(output, application);

            for (var i = 0; i < application.Steps.Count; i++)
            {
                var step = application.Steps[i];

                if (step is ContainerStep container)
                {
                    if (!outputs.Contains("container"))
                    {
                        // We should still apply the defaults here because they'll be used by
                        // the helm step.
                        DockerfileGenerator.ApplyContainerDefaults(application, container);

                        output.WriteDebugLine("skipping container");
                        continue;
                    }

                    output.WriteInfoLine("generating dockerfile");

                    var dockerFilePath = Path.Combine(application.ProjectDirectory, "Dockerfile");
                    if (File.Exists(dockerFilePath) && !force)
                    {
                        throw new CommandException("'Dockerfile' already exists for project. use --force to overwrite");
                    }

                    // force multi-phase dockerfile - this makes much more sense in the workflow
                    // where you're going to maintain the dockerfile yourself.
                    container.UseMultiphaseDockerfile = true;

                    File.Delete(dockerFilePath);

                    await DockerfileGenerator.WriteDockerfileAsync(output, application, container, dockerFilePath);
                }
                else if (step is HelmChartStep chart)
                {
                    if (!outputs.Contains("chart"))
                    {
                        output.WriteDebugLine("skipping helm chart");
                        continue;
                    }

                    output.WriteInfoLine("generating helm charts");

                    var chartDirectory = Path.Combine(application.ProjectDirectory, "charts");
                    if (Directory.Exists(chartDirectory) && !force)
                    {
                        throw new CommandException("'charts' directory already exists for project. use --force to overwrite");
                    }

                    await HelmChartGenerator.GenerateAsync(
                        output,
                        application,
                        application.Steps.Get <ContainerStep>() !,
                        chart,
                        new DirectoryInfo(chartDirectory));
                }
            }
        }