TL;DR
Run dredd image as a command line. Dredd Image at Docker Hub
docker run -it -v $PWD:/api -w /api apiaryio/dredd init
[Optional] Turn it into a script:
#!/bin/bash
echo '***'
echo 'Root dir is /api'
export MYIP=`ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'`
echo 'Host ip is: ' $MYIP
echo 'Configure URL of tested API endpoint: http://api-srv::<enpoint-port>. Set api-srv to point to your server.'
echo 'This script will set api-srv to docker host machine - ' $MYIP
echo '***'
docker run -it --add-host "api-srv:$MYIP" -v $PWD:/api -w /api apiaryio/dredd dredd $1
[Optional] And put this script in a folder that is in your PATH variable and create an alias for short it
alias dredd='bash ./scripts/dredd.sh'
Code at Github gist.