Nextcloud and Collabora require a reverse-proxy in order to work together. Collabora requires a SSL connexion in order to work. This can be a bit overwhelming to setup.
This project re-uses Nextcloud internal apache2 server as reverse-proxy for collabora. It also removes collabora's SSL use as it's only accessible locally.
Build a modified collabora/code docker image that removes SSL:
docker build -t collabora:nossl collabora/
Run collabora
docker run -d --name collabora -p 9980:9980 -e "domain=your\\.domain\\.here" -e "username=admin" -e "password=S3cRet" --cap-add MKNOD collabora:nossl
Go to http://your.domain.here:9980 on your browser, it should display ok (it might also be loading forever which is also good). The server can take a while to start responding.
If you have still nothing try restarting the container:
docker stop collabora
docker start collabora
If Collabora refuses to work, you may be having trouble with the docker volume driver. I had to use overlay2 in order for it to work.
Build nextcloud with the reverse proxy configured for collabora:
docker build -t nextcloud nextcloud/
Run nextcloud:
docker run -d -p 80:80 nextcloud
Next you have to configure Nextcloud to tell it to use Collabora.
To do so, install the Collabora Application in Nextcloud.
Then, in "Administration -> Collabora Online" enter collabora's address and the port 9980.
It has to match one of the domain you used in Collabora's Docker run.
The Apache configuration assume Collabora and Nextcloud are on the same host.
172.168.0.1 is the equivalent of localhost but for docker.
If you have a message telling you that your file is not compatible, you have to restart Collabora.
This is a weekend project, do not expect active development or support ;-)