The Nightmare of the Mid-Day Deployment 502 Error

Deploying production updates using basic FTP or manual git pull while live users are completing checkout causes broken assets, class mismatch fatals, and interrupted database transactions. Enterprise portals require zero-downtime atomic deployments.

The Atomic Symlink Pattern

  1. The CI/CD pipeline clones the latest commit into a timestamped release folder (e.g. /releases/20261016_0100/).
  2. Executes composer install --no-dev --optimize-autoloader, runs asset bundling, and pre-compiles route and config caches in isolation.
  3. Executes non-destructive database migrations.
  4. Executes an instantaneous atomic symlink swap: ln -sfn /releases/20261016_0100/ /current.
  5. Gracefully reloads PHP-FPM and triggers php artisan queue:restart without dropping a single active customer connection.