How to run tomcat as non-root with docker

foo.sh

#
# How to run tomcat as non-root with docker
#

# We want to map the tomact process to host user, which is created here
sudo useradd -r docker-tomcat

# start a container, but don't run tomcat yet
docker run -it -d --name=tomcat-intermediate -u $(id docker-tomcat -u) tomcat:8.0 /bin/sh

# while the container is running /bin/sh, fix permissions as root
docker exec -it -u root tomcat-intermediate chown -R $(id docker-tomcat -u) /usr/local/tomcat

# commit changes to a new image
docker commit tomcat-intermediate tomcat-fixed                                                                                                                                                    

# permissions are fixed, let's stop the container
docker stop tomcat-intermediate                                                                                                                                                                   

# and remove the container
docker rm tomcat-intermediate                                                                                                                                                                     

# create and start the container using the new image which has the proper permissions
docker create --name=tomcat-test1 -u $(id docker-tomcat -u) tomcat-fixed catalina.sh run                                                                                                          docker start -a tomcat-test1