Applying updates from git shouldn’t be difficult.

  1. Get the updates from a git remote

git pull
  1. Update the git submodules.

git submodule update --recursive --remote
  1. Install any updated composer dependencies.

php -d memory_limit=-1 ./vendor/bin/composer install -o
  1. Apply any database schema updates

./bin/console doctrine:schema:update --force
  1. Update the web assets.

bower install
  1. Clear the cache

./bin/console cache:clear --env=prod

That should be it.