This project template should provide a kickstart for managing your site dependencies with Composer.

If you want to know how to use it as replacement for Drush Make visit the Documentation on drupal.org.

First you need to install composer.

Note: The instructions below refer to the global composer installation. You might need to replace composer with php composer.phar (or similar) for your setup.

After that you can create the project:

composer create-project drupal-composer/drupal-project:8.x-dev some-dir --stability dev --no-interaction

With composer require ... you can download new dependencies to your installation.

cd some-dir
composer require drupal/devel:8.*

When installing the given composer.json some tasks are taken care of:

• Drupal will be installed in the web-directory.
• Autoloader is implemented to use the generated composer autoloader in vendor/autoload.php, instead of the one provided by Drupal (web/vendor/autoload.php).
• Modules (packages of type drupal-module) will be placed in web/modules/contrib/
• Theme (packages of type drupal-theme) will be placed in web/themes/contrib/
• Profiles (packages of type drupal-profile) will be placed in web/profiles/contrib/
• Creates default writable versions of settings.php and services.yml.
• Creates sites/default/files-directory.
• Latest version of drush is installed locally for use at vendor/bin/drush.
• Latest version of DrupalConsole is installed locally for use at vendor/bin/console.

Updating Drupal core is a two-step process.

1. Update the version number of drupal/core in composer.json.
2. Run composer update drupal/core.
3. Run ./scripts/drupal/update-scaffold to update files in the web directory. This will update web with whatever the latest Drupal 8 release is. Review the files for any changes and restore any customizations to .htaccess or robots.txt.
4. Commit everything all together in a single commit, so web will remain in sync with the core when checking out branches or running git bisect.

With using the "Composer Generate" drush extension you can now generate a basic composer.json file from an existing project. Note that the generated composer.json might differ from this project's file.

Composer recommends no. They provide argumentation against but also workrounds if a project decides to do it anyway.