= Proposed System Wide Change: RpmOstree - Server side composes and atomic
upgrades =
https://fedoraproject.org/wiki/Changes/RpmOstree
Change owner(s): Colin Walters <walters(a)verbum.org>
The rpm-ostree [1] tool provides a new way to deploy and manage RPM-based
operating systems. Instead of performing a package-by-package install and
upgrade on each client machine, the tooling supports "composing" sets of
packages on a server side, and then clients can perform atomic upgrades as a
tree.
The system by default preserves the previously booted deployment, providing an
"A/B partition" type feel, allowing quick system rollbacks for the entire OS
content (kernel and userspace).
This is a dependency of the Changes/Atomic_Cloud_Image. [2]
== Detailed Description ==
rpm-ostree is far from the first effort in the field of "image-like" update
systems in Fedora. The StatelessLinux [3] project was first prototyped in
Fedora Core 6 timeframe. Today, particularly in the cloud, many deployments
perform OS upgrades by terminating an instance, and booting a new OS image and
having it discover previous state stored in an external volume or network
store.
Another model is to perform an atomic upgrade by delivering the OS content via
an ISO or USB stick, and simply swapping it out, then rebooting. The oVirt
Node [4] is an example of this model.
The most challenging case though is stateful systems that require
online/incremental Internet/Intranet connected upgrades. This is the default
model for traditional Fedora package managers such as yum. A common approach
for this to have an "A/B" partition model, and to use rsync or a custom tool
to perform upgrades offline into the non-active partition.
rpm-ostree is attempting to address this last case, but in a more flexible and
dynamic fashion. It has some of the flexibility of package systems, with the
atomic upgrade and rollback of image-based systems. Furthermore, rpm-ostree
intends to bind together the world of packages with an image-like update
system. For example, an "rpm-ostree upgrade" command can show the system
administrator the package-level diff.
In the future, the intention is for rpm-ostree to further gain package-system
like features. See package layering prototype [5]. An active git branch uses
libhif [6].
== Scope ==
* Proposal owners: work on
http://projectatomic.io upstream
* Other developers:
** Anaconda: Help maintain rpmostreepayload.py
** Anaconda/Architecture porters: Backends for the OSTree bootloader code,
similar to grubby
** RPM content:
*** Use systemd-tmpfiles instead of placing content in /var (TODO: better docs
for this)
*** Change "rootfiles" and "bash" to not require files in /root by
default
(TODO: bugzilla entry)
* Release engineering: Create trees from package set, mirroring support
* Policies and guidelines: TODO: Guideline for /var
[1]
https://github.com/projectatomic/rpm-ostree
[2]
https://fedoraproject.org/wiki/Changes/Atomic_Cloud_Image
[3]
https://fedoraproject.org/wiki/StatelessLinux
[4]
http://www.ovirt.org/Node_Building
[5]
https://lists.projectatomic.io/projectatomic-archives/atomic-devel/2014-O...
[6]
https://github.com/projectatomic/rpm-ostree/pull/81