AWS container service: set max_map_count

I found a solution:

1. create an empty container
2. Launch an EC2 inside the previous container: http://docs.aws.amazon.com/AmazonECS/latest/developerguide/launch_container_instance.html
3. Add the user data (http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/user-data.html) as follow:

#!/bin/bash
echo vm.max_map_count=262144 >> /etc/sysctl.conf
sysctl -w vm.max_map_count=262144

Now the EC2 instance is properly configured.