Sample .tugboat/config.yml for a Drupal 8 contrib project (webform). Inspired by https://github.com/q0rban/tugboat-drupal

config.yml

services:
  php:
    image: q0rban/tugboat-drupal:8.8
    default: true
    http: false
    depends: mysql
    commands:
      update: |
        set -eux
        # Check out a branch using the unique Tugboat ID for this repository, to
        # ensure we don't clobber an existing branch.
        git checkout -b $TUGBOAT_REPO_ID
        # Composer is hungry. You need a Tugboat project with a pretty sizeable
        # chunk of memory.
        export COMPOSER_MEMORY_LIMIT=-1
        # This is an environment variable we added in the Dockerfile that
        # provides the path to Drupal composer root (not the web root).
        cd $DRUPAL_COMPOSER_ROOT
        # We configure the Drupal project to use the checkout of the module as a
        # Composer package repository.
        composer config repositories.tugboat vcs $TUGBOAT_ROOT
        # Now we can require this module, specifing the branch name we created
        # above that uses the $TUGBOAT_REPO_ID environment variable.
        composer require drupal/webform:dev-$TUGBOAT_REPO_ID -vvv

        # Install Drupal on the site.
        vendor/bin/drush \
          --yes \
          --db-url=mysql://tugboat:tugboat@mysql:3306/tugboat \
          --site-name='This is a live preview' \
          --account-pass=admin \
          site:install standard

        # Set up the files directory permissions.
        mkdir -p $DRUPAL_DOCROOT/sites/default/files
        chgrp -R www-data $DRUPAL_DOCROOT/sites/default/files
        chmod 2775 $DRUPAL_DOCROOT/sites/default/files
        chmod -R g+w $DRUPAL_DOCROOT/sites/default/files

        # Enable the module.
        vendor/bin/drush --yes pm:enable webform
        echo 'hi again!'

      build: |
        set -eux
        # Delete and re-check out this branch in case this is built from a Base Preview.
        git branch -D $TUGBOAT_REPO_ID && git checkout -b $TUGBOAT_REPO_ID || true
        export COMPOSER_MEMORY_LIMIT=-1
        cd $DRUPAL_COMPOSER_ROOT
        composer install --optimize-autoloader
        # Update this module, including all dependencies.
        composer update drupal/webform --with-all-dependencies
        vendor/bin/drush --yes updb
        vendor/bin/drush cache:rebuild
        echo 'oh hi!'

  mysql:
    image: tugboatqa/mariadb