How to run server docker image?

ubuntu@VM-30-101-ubuntu:~$ docker run --rm -v $(pwd):/repo
usage: fdroid [-h|–help|–version] []

Valid commands are:
build Build a package from source
init Quickly start a new repository
publish Sign and place packages in the repo
gpgsign Add gpg signatures for packages in repo
update Update repo information for new packages
verify Verify the integrity of downloaded packages
checkupdates Check for updates to applications
import Add a new application from its source code
install Install built packages on devices
readmeta Read all the metadata files and exit
rewritemeta Rewrite all the metadata files
lint Warn about possible metadata errors
scanner Scan the source code of a package
dscanner Dynamically scan APKs post build
stats Update the stats of the repo
server Interact with the repo HTTP server
signindex Sign indexes created using update --nosign
btlog Update the binary transparency log for a URL
signatures Extract signatures from APKs

That looks like your running it correctly. The name fdroidserver is a bit of a misnomer, since there isn’t any daemon or server process. Its really the tools needed to process files to post to a webserver.