A simple Dockerfile that creates a tomcat7 container, with Java 8.
The default manager account is admin/admin123, but you can change the password at runtime by providing the ADMIN_PWD environment variable in the docker run command.
docker run -d -e ADMIN_PWD=mysupersecretpassword danielroy/tomcat7-admin
You can change the port as well:
docker run -d -p [portnumber]:8080 danielroy/tomcat7-admin