This is a file formatted as config.{environment}.json should be stored in the root directory of your ghost instance (if you have any overrides). In case you didn’t change anything the resizing should be configured to work out of the box.
Regarding config.production.json, I didn’t change anything.
That’s why I feel something is wrong as in the test I did, no resizing nor compression was applied.
@pascalandy To make this absolutely clear, sharp is an optional binary dependency. This means that if it tries to install and fails (which it might do for many reasons - binary dependencies are tricky), Ghost carries on and falls back to not optimising images just like it did before.
This is why you’re being asked if sharp actually installed for you or not.
@pascalandy I think this is the pertinent line in your log:
[17:12:35] → [5/5] Building fresh packages...
[17:12:36] → info This module is OPTIONAL, you can safely ignore this error
[17:12:37] → Done in 18.51s.
Seems to suggest the optional module didn’t install. Maybe you have other logs from ghost-cli available to see what the error was?