f4877419ac
The old branch examples use Fedora 26 which is almost EOL. The new Fedora 27 examples show off the various `testing` and `updates` branches, as well as the support for different arches. Closes: #1175 Approved by: cgwalters
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Administering an rpm-ostree based system
At the moment, there are four primary commands to be familiar with on
an rpm-ostree based system. Also remember that in a Project Atomic
system, the atomic host command (from the
Atomic command) is an
alias for rpm-ostree.
# rpm-ostree status
Will show you your deployments in the order in which they will appear in the
bootloader, the first deployment in the list being the current default one. The
● shows the currently booted deployment.
# rpm-ostree upgrade
Will perform a system upgrade, creating a new deployment (root filesystem) and
set it as the default for the next boot. You should use systemctl reboot
shortly afterwards.
# rpm-ostree rollback
This rolls back to the previous state, i.e. the default deployment changes
places with the non-default one. By default, the rpm-ostree upgrade will keep
at most two bootable "deployments", though the underlying technology supports
more.
# rpm-ostree deploy <version>
This command makes use of the server-side history feature of OSTree. It will search the history of the current branch for a commit with the specified version, and deploy it. This can be used in scripts to ensure consistent updates. For example, if the upstream OS vendor provides an update online, you might not want to deploy it until you've tested it. This helps ensure that when you upgrade, you are getting exactly what you asked for.
Hybrid image/packaging via package layering
It is possible to dynamically add more packages onto the system that are not part of the commit composed on the server. These additional "layered" packages are persistent across upgrades, rebases, and deploys (contrast with the ostree unlocking mechanism).
This is where the true hybrid image/package nature of rpm-ostree comes into play; you get a combination of the benefits of images and packages. The package updates are still fully transactional and offline.
For example, you can use package layering to install 3rd party
kernel modules, or userspace driver daemons such as pcsc-lite-ccid.
While most software should go into a container, you have full flexibilty
to use packages where it suits.
# rpm-ostree install <pkg>
Will download the target package, its dependencies, and create a new deployment
with those packages installed. To remove layered packages, use rpm-ostree uninstall.
By default, every rpm-ostree operation is "offline" - it has no effect
on your running system, and will only take effect when you reboot. This "pending" state is
called the "pending deployment". Operations can be chained; for example,
if you invoke rpm-ostree upgrade after installing a package, your new root
will upgraded with the package also installed.
Rebasing
rpm-ostree rebase -b $branchname
Your operating system vendor may provide multiple base branches. For example, Fedora Atomic Host has branches of the form:
fedora/27/aarch64/atomic-hostfedora/27/aarch64/testing/atomic-hostfedora/27/aarch64/updates/atomic-hostfedora/27/ppc64le/atomic-hostfedora/27/ppc64le/testing/atomic-hostfedora/27/ppc64le/updates/atomic-hostfedora/27/x86_64/atomic-hostfedora/27/x86_64/testing/atomic-hostfedora/27/x86_64/updates/atomic-host
You can use the rebase command to switch between these; this can represent a
major version upgrade, or logically switching between different "testing"
streams within the same release. Like every other rpm-ostree operation, All
layered packages and local state will be carried across.
Other local state changes
See man rpm-ostree for more. For example, there is an rpm-ostree initramfs
command that enables local initramfs generation.
Experimental interface
There is a generic rpm-ostree ex command that offers experimental features.
One of those is rpm-ostree ex livefs, which offers the ability to apply
changes from the pending deployment to the booted deployment.
See man rpm-ostree for more information.
Filesystem layout
The only writable directories are /etc and /var. In particular,
/usr has a read-only bind mount at all times. Any data in /var is
never touched, and is shared across upgrades.
At upgrade time, the process takes the new default /etc, and adds
your changes on top. This means that upgrades will receive new
default files in /etc, which is quite a critical feature.
For more information, see OSTree: Adapting.
Operating system changes
- The RPM database is stored in
/usr/share/rpm, and is immutable. - A package nss-altfiles
is required, and the system password database is stored in
/usr/lib/passwd. Similar for the group database. This might change in the future; see this issue.