Apparently, the current method to auto-start Docker containers (from Docker 1.2) is to use restart policies. This will control how Docker should handle starting of the container upon startup and re-starting of the container when it exits. I've used the 'always' option so far, and can confirm that it makes Docker auto-start the container at system boot:
sudo docker run --restart=always -d myimage
Restart Policies Using the --restart flag on Docker run you can
specify a restart policy for how a container should or should not be
restarted on exit.
no - Do not restart the container when it exits.
on-failure - Restart the container only if it exits with a non zero
always - Always restart the container regardless of the exit status.
You can also specify the maximum amount of times Docker will try to
restart the container when using the on-failure policy. The default is
that Docker will try forever to restart the container.
$ sudo docker run --restart=always redis
This will run the redis
container with a restart policy of always so that if the container
exits, Docker will restart it.
$ sudo docker run --restart=on-failure:10 redis
This will run the
redis container with a restart policy of on-failure and a maximum
restart count of 10. If the redis container exits with a non-zero exit
status more than 10 times in a row Docker will abort trying to restart
the container. Providing a maximum restart limit is only valid for the