Dockerfile

FROM collabora/code

ADD start.sh /
CMD bash start.sh

start.sh

#!/bin/sh

# Fix lool resolv.conf problem (wizdude)
rm /opt/lool/systemplate/etc/resolv.conf
ln -s /etc/resolv.conf /opt/lool/systemplate/etc/resolv.conf

# Replace trusted host and set admin username and password
#perl -pi -e "s/localhost<\/host>/${domain}<\/host>/g" /etc/loolwsd/loolwsd.xml
#perl -pi -e "s/<username desc=\"The username of the admin console. Must be set.\"><\/username>/<username desc=\"The username of the admin console. Must be set.\">${username}<\/username>/" /etc/loolwsd/loolwsd.xml
#perl -pi -e "s/<password desc=\"The password of the admin console. Must be set.\"><\/password>/<password desc=\"The password of the admin console. Must be set.\">${password}<\/password>/g" /etc/loolwsd/loolwsd.xml
perl -pi -e "s/<server_name desc=\"Hostname:port of the server running loolwsd. If empty, it's derived from the request.\" type=\"string\" default=\"\"><\/server_name>/<server_name desc=\"Hostname:port of the server running loolwsd. If empty, it's derived from the request.\" type=\"string\" default=\"\">${server_name}<\/server_name>/g" /etc/loolwsd/loolwsd.xml

# Start loolwsd
su -c "/usr/bin/loolwsd --version --disable-ssl --o:storage.filesystem[@allow]=true --o:logging.level=trace --o:logging.file.property[7]=true --o:sys_template_path=/opt/lool/systemplate --o:lo_template_path=/opt/collaboraoffice5.3 --o:child_root_path=/opt/lool/child-roots --o:file_server_root_path=/usr/share/loolwsd" -s /bin/bash lool

Copy both of these files in a directory and then run following in that directory:
docker build ./

Note down the image hash built from it and then run it using docker run. Check if it fails to fork children in first attempt.