Issue
I'm not seeing the logs I expect from an app deployed via the container registry and runtime.
Resolution
As with Common Runtime dynos, container based apps with capture everything on stdout and stderr and send this to the Heroku logging system. It should then be accessible via the normal methods e.g. heroku logs, logging add-ons, custom log drains etc. https://devcenter.heroku.com/articles/logging
If you aren't seeing the logs you expect, please ensure that you aren't logging to files inside your container. Instead, you need to configure the application to log on stdout.
For apps that previously used the official PHP buildpack, this has an option to redirect file based logs to stdout for Apache or Nginx https://devcenter.heroku.com/articles/php-logging#adding-logging-for-legacy-applications This is not available in container based apps and you will still need to configure your processes to log to stdout.