Uses Docker to pull an Image to the machine.

docker-script.sh

# Install the ECR Credential Helper that automatically authenticates with ECR.
sudo yum install amazon-ecr-credential-helper -y

# Configure Docker to use the credential helper.
mkdir ~/.docker/
cat > ~/.docker/config.json << EOF
{
    "credsStore": "ecr-login"
}
EOF

# Docker is not started when the machine is booted, so start it.
sudo service docker start

# Pull the Image with docker.
# Since sudo is used, explicitly specify the location of the Docker config file.
sudo docker --config /home/ec2-user/.docker pull $IMAGE

# Verify the presence of the Image on the machine.
sudo docker image ls