Adding BLT to an existing project

Adding BLT to an existing project can be much more complex than simply creating a new site with BLT. There are a few reasons for this:

  1. BLT expects your project to have a particular directory structure and set of files.
  2. Your existing dependencies may conflict with BLT's dependencies.


  1. The Drupal root must be in a top-level docroot directory.
  2. You must already use Composer to manage site dependencies. If you don't, please see Using Composer to manage Drupal site dependencies and modify your project accordingly.
  3. Ensure that your dependencies are all up to date via composer update. Assert that these updates do not break your project.

To add BLT to a pre-existing Drupal project, do the following:

  1. cd into your existing project directory.
  2. Set Composer's minimum-stability to dev and prefer-stable to true:

    composer config minimum-stability dev
    composer config prefer-stable true
  3. Add BLT via composer:

    rm -rf vendor composer.lock
    composer require acquia/blt:^9.0.0 --no-update
    composer update
  4. Continue following instructions after the composer create-project command in Creating a new project with BLT.