install docker-cli on centos/amazon-linux

docker-cli-install.sh

## optional: run the amazon cli container
docker run -ti --rm --name amazon-cli \
  -v ~/.aws:/root/.aws \
  -v ~/.docker:/root/.docker \
  -v /var/run/docker.sock:/var/run/docker.sock \
  --entrypoint /bin/bash \
  amazon/aws-cli


## (slow) optional: generate yum repository configuration using an additional tool
yum install yum-utils -y

yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

## (fast) generate yum repo info by pasting text into a file
curl -so /etc/yum.repos.d/docker-ce.repo \
  https://download.docker.com/linux/centos/docker-ce.repo

## install docker-ce-cli
yum --enablerepo=docker-ce-stable --disablerepo=amzn2-core install docker-ce-cli -y