Port forwarding in when running a Tomcat Docker in an AWS Elastic Beanstalk application

I have a Tomcat 7.0 webapp running inside a docker container on AWS Elastic Beanstalk (EB) (I followed the tutorial here).

When I browse to my EB url myapplication.elasticbeanstalk.com, I get a 502 Bad Gateway by served by nginx. So its immediately clear that my port 80 is not forwarding to my container. When I browse to myapplication.elasticbeanstalk.com:8888 (another port I exposed in my Dockerfile) the connection is refused (ERR_CONNECTION_REFUSED). So I SSH'ed into the AWS instance and checked the docker logs, which show that my Tomcat server has started successfully, yet obviously hasn't processed any requests.

Does anyone have any idea my port 8888 appears not to be forwarding to my container?

Executing the command (on the AWS instance):

sudo docker ps -a

gives:

CONTAINER ID        IMAGE                              COMMAND             CREATED             STATUS                     PORTS                        NAMES     
c353e236da7a        aws_beanstalk/current-app:latest   "catalina.sh run"   28 minutes ago      Up 13 minutes              80/tcp, 8080/tcp, 8888/tcp   sharp_leakey  

which shows port 80, 8080, and 8888 as being open on the docker container.

My Dockerfile is fairly simple:

FROM tomcat:7.0

EXPOSE 8080
EXPOSE 8888
EXPOSE 80

and my Dockerrun.aws.json file is:

{
  "AWSEBDockerrunVersion": "1",
  "Image": {
    "Name": "myusername/mycontainer-repo"
  },
  "Authentication": {
    "Bucket": "mybucket",
    "Key": "docker/.dockercfg"
  },
  "Ports": [
    {
      "ContainerPort": "8888"
    }
  ]
}

Does anyone see where I could be going wrong? I'm not even sure where to look at this point.

Also, my AWS security group for the instance is open on port 80, 8080, and 8888. Any advice would be greatly appreciated! I'm at a loss here.