userdata.sh

#!/bin/bash
cat<<-EOF > /etc/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.io
Requires=docker.socket

[Service]
Environment="TMPDIR=/var/tmp/"
ExecStartPre=/bin/mount --make-rprivate /
LimitNOFILE=1048576
LimitNPROC=1048576
# Run docker but don't have docker automatically restart
# containers. This is a job for systemd and unit files.
ExecStart=/usr/bin/docker --daemon --storage-driver=btrfs --host=fd:// --host=0.0.0.0:4243

[Install]
WantedBy=multi-user.target
EOF

systemctl stop docker
systemctl disable docker
systemctl enable /etc/systemd/system/docker.service
systemctl start docker