django web app deployment gunicorn + aws ECS issue - django

Question

I have working django REST API docker image with following dependencies:
python 3.5.2, django 1.10.6, djangorestframework 3.6.2, gevent 1.2.2
In my dockerfile, port 5000 is exposed.
docker command:
/usr/local/bin/gunicorn --log-level=DEBUG --worker-class gevent --timeout=300 config.wsgi -w 4 -b :5000
In the ECS task definition, 5000 container port is forwarded to port 80 of the host. The security group has an inbound rule allowing everyone at port 80.
When I ran the ECS task with this ECS task definition, following are the application logs, which seem fine.
[2017-09-13 16:45:34 +0000] [9] [INFO] Starting gunicorn 19.6.0
[2017-09-13 16:45:34 +0000] [9] [INFO] Listening at: http://0.0.0.0:5000 (9)
[2017-09-13 16:45:34 +0000] [9] [INFO] Using worker: gevent
[2017-09-13 16:45:34 +0000] [12] [INFO] Booting worker with pid: 12
[2017-09-13 16:45:34 +0000] [13] [INFO] Booting worker with pid: 13
[2017-09-13 16:45:35 +0000] [15] [INFO] Booting worker with pid: 15
[2017-09-13 16:45:35 +0000] [16] [INFO] Booting worker with pid: 16
But I am unable to access the service endpoints using the EC2 instance's public IP/Public DNS address.
I tried to get into the running container and curl the application url curl localhost:5000. Following are the logs that I see (the connections are closed)
[2017-09-13 17:42:42 +0000] [14] [DEBUG] GET /
[2017-09-13 17:42:42 +0000] [14] [DEBUG] Closing connection.
[2017-09-13 17:42:56 +0000] [12] [DEBUG] GET /
[2017-09-13 17:42:56 +0000] [12] [DEBUG] Closing connection.
[2017-09-13 17:53:20 +0000] [14] [DEBUG] GET /users/get_mfatype/
[2017-09-13 17:53:20 +0000] [14] [DEBUG] Closing connection.
The same docker image is working as expected when I run locally. I even tried running the same docker image inside EC2 instance, which is working fine.
I am not able to find the root cause why the application is not running as ECS task.
Am I missing anything?