Processing build steps#

Project generation is described through a set of so-called “build steps”. Each step is configured by the step property (see Configuration#Structure).


  1. Once the user selected a project type, a new Generator is created

  2. The Generator runs through all configured steps

    1. Step is created by using the StepFactory

    2. Step is executed by calling $step->run($result)

    3. On step failure:

      • All applied steps are reverted by calling $step->revert($result)

      • Further execution is terminated

    4. BuildResult is returned

Reverting failed steps#

When steps are executed, they may perform I/O operations on the generated project or other directories. If any of those operations fail, it should be possible to revert them. For this, steps are required to implement a revert() method. It is called for all previously applied steps once any step in the project generation process fails.

Applying processed steps#

Each successfully processed step should itself apply to the current build result. This is the only way for the application to recognize that the step was executed. If the step is not applied to the build result, it cannot be reverted.


 1use CPSIT\ProjectBuilder\Builder;
 3final class MyStep implements Builder\Generator\Step\StepInterface
 5    public function run(Builder\BuildResult $buildResult): bool
 6    {
 7        // Do anything...
 9        if ($successful) {
10            $buildResult->applyStep($this);
11        }
13        return $successful;
14    }
16    // ...


Each step must implement StepInterface. However, some variants for steps exist giving them additional possibilities in the project generation lifecycle:

  • If a step is actively processing files, it should implement ProcessingStepInterface. This way, it is possible to provide information about which files were processed after successful project generation.

  • Steps may also be able to stop further processing, thus being stoppable. For this, StoppableStepInterface can be implemented. The method isStopped() is then called after the step is processed to determine whether further steps should be processed.

Available steps#

The following steps are currently available:

Collect build instructions#

This step walks through all configured properties. It uses the InputReader to collect build instructions for property. All collected build instructions result in a list of template variables. Those can be used in other steps when rendering Twig templates or taking decisions based on user-provided data.

Generate build artifact#

This step should always be configured as last step prior to mirroring processed files. It generates a build artifact that contains information about the used generator and template packages as well as all user input and more general information about how the new project was generated. By default, the artifact file is stored in .build/build-artifact.json of the new project. However, the artifact path can be overwritten via the artifactPath option.

See also

Read more at Architecture#Build artifact.

Install Composer dependencies#

By using this step, it is possible to install additional Composer dependencies. Those dependencies should provide shared source files. The appropriate composer.json must be in the project type’s template folder.

See also

Read more at Configuration.

Mirror processed files#

This is typically one of the last configured steps. It asks for confirmation to mirror all previously processed source files and shared source files to the target project directory. It also takes care of cleaning up the target directory as well as removing the previously generated temporary directory.

Process source files#

Copies all files in the project type’s templates/src folder to a temporary directory. If a file has the .twig extension, it is first processed by the Twig renderer. All previously collected build instructions are passed as template variables to the renderer.

File conditions#

In the project template config, it is possible to provide a set of file conditions. Each file condition applies to a given path. The specified condition is then used in the step to decide whether to include or exclude the appropriate file. All other files will always be processed.

Target file#

A file condition may also contain an additional target configuration. It can be used to configure a different target file location than the default location, e.g. if files with different contents should result in the same target file, depending on a given file condition.

Multiple conditions#

It is possible to define more than one file condition for a single file. This is useful in combination with the configuration of a file target, e.g. if the file is expected on different locations for different versions of a configured framework. If more than one file condition evaluates to true, the first configured target is always used.

Process shared source files#

The behavior of this step is similar to the processSourceFiles step. However, this step processes shared source files inside the shared folder of the project type’s templates directory. These files are normally added during runtime by the installComposerDependencies step.

See also

Read more at Configuration#Shared source files.

Run Command#

The runCommand enables you to execute custom shell commands in the generated project directory. Place your command step after dependent steps have been executed. Multiple steps are permitted.

Please keep in mind that an already executed command cannot be reverted.


Users need to confirm the execution of each runCommand by default. You may, however, skip this confirmation and have the command run without user intervention by setting skipConfirmation: true in the step option configuration.

Additionally, you can opt to ignore the result of a potentially failing command run with allowFailure: true to ensure the project generation would not abort because of that failure.

Show next steps#

This step should always be configured as last step. It shows the user how to manually continue the build process after successful project generation. This can be some sort of “Getting started with the new project”. The steps are provided by a Twig template file, configured via the templateFile option.