My settings.php file looks for a settings.local.php file. DDEV also wants to provide a file named this containing database credentials. What's the best way for them to coexist? Should I also look for a local.settings.php file and place my custom overrides there?
In recent versions ddev uses a "settings.ddev.php" (created during ddev config) to provide its own db settings; So the normal way to provide your own settings would be to edit settings.local.php and make sure it gets included by the settings.php file.
In addition:
* If any settings file does not contain the string "#ddev-managed" then ddev will not touch it.
* You can always use project-type=php (type: php in .ddev/config.yaml, or ddev config --project-type=php) and ddev won't try to do anything at all with settings.