The author released an improved docker image here:
https://github.com/kamax-io/mxisd/blob/master/Dockerfile
https://hub.docker.com/r/kamax/mxisd/
This Dockerfile builds an small docker image for the Matrix Identity Server Daemon mxisd https://github.com/kamax-io/mxisd.
The config dir of mxisd (/etc/mxis) gets mounted into the host filesystem (/data/mxisd). There you have to put the config or mxisd will not run.
docker build -t doofy/mxisd .
https://raw.githubusercontent.com/kamax-io/mxisd/master/application.example.yaml
cp application.example.yaml application.yaml
mv application.yaml /data/mxisd/mxisd.yaml
docker run -v /data/mxisd:/etc/mxis -p 8090:8090 --name mxisd doofy/mxisd