Permission issue does not allow to create config file

[afdaniele]

If we install compose in a directory that does not belong to www-data (very common when the code is mounted from outside a Docker container), compose cannot create the configuration file for the core package at boot. This prevents the default value of maintenance_mode from metadata.json to be written, and the user is redirected to maintenance since the default value passed to Core::getSetting('maintenance_mode', 'core') is true.

We either show an error in this case or make it easier for the user to figure out what the issue is. Perhaps, we could use the entrypoint script to check and notify the user somehow (on-the-fly written page?).

[afdaniele]

Note, this happens when the Docker container is run before pulling the code. In fact, the entrypoint takes care of chown-ing the code already.