Symfony's configuration system has improved a lot in recent years. Version 4.2 brings a lot of minor improvements that all together give an even better developer experience. Let's step back and look at how we can tackle all of the most common problems using the new approaches! This will include tricks for configuring services as easily as possible, handling different environment configuration and the hugely important topic of environment variables and secrets. Best of all, we'll discuss some strategies to migrate your existing apps so you're never going to be left behind.