Maybe this is a long standing issue...
When the container is built using the steps outlined here: https://docs.opendap.org/index.php?title=Docker_container_build#Build_the_docker_container the resulting container works OK for regular DAP, et c., responses but fails for the ncWMS one with the message:
To reproduce, build the container, start it using docker run -h hyrax -p 8080:8080 --name hyrax_container_ncwms hyrax_image_ncwms. I used http://localhost:8080/opendap/, then goto the /data/nc/coads dat set, follow the viewers link. Both Godiva and Web Mapping Service return the error.