extension-installer | Infection Extension Installer | Browser Plugin library

Your docker containers don't have any knowledge of the users that may or may not exist on the host machine, so unless you've built those in with their accompanying config and directory structure the only thing you're getting out of feeding docker your local UID and GID is "running the container as something other than root", which is good.

But generally you don't want to tie a docker container/image to the particular environment that it is launched from, eg: requiring a user with the same name as your local user exist within the container, plus all of its associated directories and such.

In this specific case it looks like artisan just wants to cache some config, and you can control where that lands with the environment variable:

The docker part seems good. I see that you're using Xdebug with PHP-FPM and according to Xdebug:

XDEBUG_MODE environment variable

Some web servers have a configuration option to prevent environment variables from being propagated to PHP and Xdebug.

For example, PHP-FPM has a clear_env configuration setting that is on by default, which you will need to turn off if you want to use XDEBUG_MODE.

You might want to checkout your PHP-FPM config.

I encountered the same error and solved the problem by changing the DB_HOST field in the .env file. You can access the container and IP addresses with the command below. You can solve the problem by typing your container IP running for mysql into the DB_HOST field.

The problem is that you haven't updated symfony/swiftmailer-bundle - as given in the composer.json, you tried to install at most v2.6.7 which requires symfony/http-kernelin v2.7 or v3.x. This is not compatible with symfony/framework-bundle in v4.4, as this requires symfony/http-kernel to be of that same v4.4 branch.

Conclusion: also update symfony/swiftmailer-bundle to at least v3.1 which is the first one to be compatible with Symfony v4.