Problem:
When using the official nextcloud docker image, you will see a message like
Module php-imagick in this instance has no SVG support. For better compatibility it is recommended to install it.
on the system overview page
Solution
This is a bug in the docker image and will likely be resolved soon – in the meantime, we can just manually install the required library on the container:
docker-compose exec nextcloud apt -y update docker-compose exec nextcloud apt -y install libmagickcore-6.q16-6-extra
If you re-create the container, this change will be lost, but in my opinion it’s best to opt for a simple solution here and possible do it again once or twice as opposed to a permanent but much more labour-intensive procedure like updating the docker image and later migrating back to the official image.