How does symfony know which configuration file should be used currently?

Question

I took over a new project based on symfony and found that there are many configuration files under /app/config, config_stage.yml, config_production.yml, etc. The system has been using the information in config_stage.yml to connect to the database. Now I need to switch to config_production. yml, don’t know what needs to be changed? After searching the full text, I can't seem to find which file references config_stage.yml.

Answer 1

.../app/AppKernel.php

public function registerContainerConfiguration(LoaderInterface $loader)
{
    $loader->load(__DIR__.'/config/config_'.$this->getEnvironment().'.yml');
}