Set UID and GID on Run

[mastermindg]

It would be nice to match existing UID's and GID's on shared volumes. This should be a trivial addition.

[tianon]

(Sorry for the delay!)

For the FPM variants, this is as trivial as using Docker's --user directive and Drupal should Just Work.

For the Apache variants, you should be able to accomplish this by using the APACHE_RUN_USER environment variable. 👍