[ubuntu-cloud] Can I reboot from cloud-init?

[Scott Moser]

On Mon, 24 Sep 2012, Nick Barcet wrote:

> On 09/23/2012 04:50 PM, Dave Hein wrote:
> > I'm trying to setup a cloud-config file to invoke a script that will run
> > apt-get to update packages and install a few additional packages.
> > Because the kernel can be updated by the 'apt-get upgrade', I want to
> > reboot at the end to activate the new kernel.

This isn't *really* well tested, but one of our kernel developers
basically wanted to do exactly what you were requesting.
Under bug 1038108 (http://pad.lv/1038108) I added a cloud-config syntax
for doing explicitly this.

The config snippet, will do what you'd want in 12.10 and later.  It
reboots immediately after 'apt-get upgrade' by cloud-init if there is a
reboot required.  This also allows you to install new packages and make
sure that by the time your user-data scripts run, you're in the right
kernel and modules for that kernel too.

  #cloud-config
  apt_upgrade: True
  apt_reboot_if_required: True

cloud-init is still a bit annoying in the logs to the console when this
runs (as it's logging is going to rsyslog, and both cloud-init and rsyslog
get killed by 'reboot'), but it generally works, and anything that was
going to run after the 'apt_update_upgrade' config module will just run
after reboot.

>
> Hello Dave,
>
> Our best practice, in your case, is to modify the script that launches a
> new instance to always make sure you boot from the latest image in the
> suite you are running.  On an officially maintained cloud, our images

I agree here, this is definitely the best practice.  If you're launching
images in automation, you should hit /query to find what ami to launch.

> are updated as soon as a security update that mandates it is published,
> or at least every two months.  This means that by launching the latest
> image, you are quite unlikely to have a kernel update to be done.  This

Unfortunately, we've not done as good of a job of keeping up with updates
as we'd like.  The plan is to get that to being completely automated, and
ideally pretty much in lock-step with kernel upgrades.  Now, however, it
still requires someone to do manual work, and as a result we've not done
new image releases as much as we'd like.

> also limits the number of updates that you will have to pull, over time,
> for a given suite.
>
> To do so on EC2, I would recommend using the query interface on
> cloud-images.ubuntu.com [1].  Look at the file and URL, I think it is
> self explanatory, but more explanations are available at [2].
>
> [1] http://cloud-images.ubuntu.com/query/precise/server/released.current.txt
> [2]https://help.ubuntu.com/community/UEC/Images#Machine_Consumable_Ubuntu_Cloud_Guest_images_Availability_Data
>
> Hope this helps,
> Nick
>
>