UPDATE (March 2020, thanks @ic): I don't know the exact AMI version but yum install docker now works on the latest Amazon Linux 2. The instructions below may still be relevant depending on the vintage AMI you are using.
Amazon changed the install in Linux 2. One no-longer using 'yum' See: https://aws.amazon.com/amazon-linux-2/release-notes/
sudo amazon-linux-extras install docker
sudo service docker start
Install MySQL 5.6 in Ubuntu 16.04
Ubuntu 16.04 only provides packages for MySQL 5.7 which has a range of backwards compatibility issues with code written against older MySQL versions.
Oracle maintains a list of official APT repositories for MySQL 5.6, but those repositories do not yet support Ubuntu 16.04. However, the 15.10 repos will work for 16.04.
Uninstall existing mysql 5.7 if any
sudo apt remove mysql-client mysql-server libmysqlclient-dev mysql-common
$ uname -r