cloud-init-dev team mailing list archive

[Garrett Holmstrom <gholms@xxxxxxxxxxxxxxxxx>]

On Tue, May 1, 2012 at 11:49 AM, jvlcek <jvlcek@xxxxxxxxxx> wrote:
> My big question:
> ----------------
>
> What triggers the modules cloud_config_modules, cloud_final_modules?

Thankfully, the answer to this one is easy.  :)

cloud-init.service calls ``cloud-init start'', which runs the modules
in cloud_init_modules.
cloud-config.service calls ``cloud-config all config'', which runs the
modules in cloud_config_modules.
cloud-final.service calls ``cloud-config all final'', which runs the
modules in cloud_final_modules.

On systems that use upstart's event functionality (read:  non-RHEL),
init scripts can trigger on a "cloud-config" event that one of
cloud-init's executables emits during the boot process.  Fedora uses
cloud-config.target, which waits for cloud-init*.service, for this
purpose instead.  If something prevents cloud-config.target from
becoming active then cloud-config.service and cloud-final.service will
fail to trigger.

Fedora 16 shipped with a nasty systemd bug that broke cloud-init's
service ordering since the EC2 image was not a release blocker.
Moreover, only the barest essentials of cloud-init worked at the time
since it was more or less rushed in at the last moment.  If you're
composing images for testing I suggest including updates where
possible.