[atomic-devel] Fedora 23 Cloud Atomic Developer Mode Preview

[Jonathan Lebon <jlebon redhat com>]

Hi all,

As some of you may already know, I've been working on adding
a new feature to the Fedora 23 Cloud Atomic image called
"Developer Mode" (I'm not sure yet if this is the correct
name for it). The Trello card is available at [1].

The high-level goal is to make Atomic more accessible by
providing a new GRUB 2 menu item labeled e.g. "Fedora 23
(Twenty Three) Developer Mode". This mode is an attempt to
provide a painless experience for folks who want to try out
Atomic, but (1) do not want to bother setting up a cloud-
init datasource, or (2) do not know anything about cloud-
init, or even (3) do not have much experience with
Linux overall.

Since the functionality is completely integrated into the
image, there are no requirements on the host system, other
than its ability to boot VMs.

When booted in Developer Mode, the following happens:
    - cloud-init uses a local built-in datasource
    - a new root password is generated
    - the root user is automatically logged in on tty1
    - the cockpit/ws image is downloaded and started
    - a tmux session is started on tty1 to provide all the
      relevant information (root password, IP address,
      Cockpit console address)

The first Developer Mode image is available at [2]. I invite
you all to try it out and let me know what you think! I've
enabled the plymouth splash screen, which for now uses the
Fedora theme, but might later be switched over to an Atomic
theme.

I'd still like to give users a more helpful welcome message
after login. Maybe we could link to a new page on
projectatomic.io which describes Developer Mode in more
details.

As Matthew Miller pointed out, one of the drawbacks of this
approach is that the GRUB 2 menu timeout will probably have
to be slightly increased to give users more time to make
their selection (at the expense of also increasing boot
times in contexts that don't care about Developer Mode).

In my experience, increasing it by only 1s (for a total of
2s) was enough, but we should probably discuss it more. We
can also minimize this by shipping with a grub.cfg that uses
a 2s timeout, but with the default of 1s, so that at the
next grub2-mkconfig (e.g. on an upgrade/rebase), it will go
back to 1s.

Code is available at [3]. Some modifications to the
kickstart file were also necessary.

Cheers,

Jonathan

---

TL;DR: I added a new boot menu item to the Atomic image so
that you don't have to set up cloud-init. You can download
it from [2].

[1] https://trello.com/c/eK54YRTp
[2] https://jlebon.fedorapeople.org/atomic-devmode/latest/
[3] https://github.com/jlebon/atomic-devmode