0c4aaf25de
Add some notes in the manual about package layering. Would be nice to have `ostree admin unlock` also be part of the ostree manual for a better contrast of the two. Looking at the other snippets in the document, this makes me think we probably should also add wrappers in `/usr/bin/atomic` for the new commands. Or maybe we should wait until they're not in preview mode anymore. Closes: #374 Approved by: cgwalters
3.3 KiB
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. The author tends to use the former on client
systems, and the latter on compose servers.
# atomic host status
Will show you your deployments, in the order in which they will appear
in the bootloader. The * shows the currently booted deployment.
# atomic host upgrade
Will perform a system upgrade, creating a new chroot, and set it as
the default for the next boot. You should use systemctl reboot
shortly afterwards.
# atomic host rollback
By default, the atomic upgrade will keep at most two bootable
"deployments", though the underlying technology supports more.
# atomic host 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.
Package layering
It is possible to 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 allows you to easily enhance the base set of packages on only some machines, or only temporarily (rather than asking to have it part of the server compose and affecting every machine). For example, you may wish to permanently install some diagnostics tools on a test machine.
# rpm-ostree pkg-add <pkg>
Will download the target package, its dependencies, and create a new deployment with those packages installed.
# rpm-ostree pkg-remove <pkg>
Will create a new deployment with the target package removed.
Note that package layering is currently in preview mode and as such may change interface or functionality before being declared stable.
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.