Using higher level build tooling
rpm-ostree compose tree was intended to be a "high level" tool,
but that didn't work out very well in practice. Today, you should consider
it as a low level tool. For example, most people that want to generate
OSTree commits also want to generate bootable disk images, and rpm-ostree
has nothing to do with that.
One example higher level tool that takes care of both OSTree commit generation and bootable disk images is coreos-assembler.
Background on managing an OSTree repository
Before you get started, it's recommended to read (at least) these two sections of the OSTree manual:
Generating OSTree commits from a CentOS base
First, you'll need a copy of
rpm-ostree. The current recommendation is to use
a privileged container, but you can also install
rpm-ostree directly to a
physical or virtual machine.
You can create a privileged container with e.g.
--privileged registry.fedoraproject.org/fedora:27 .... However you create the
yum -y install rpm-ostree.
A good first thing to try would be using the CentOS Atomic Host metadata to generate a custom host.
One time setup, where we clone the git repository, then make two OSTree repos, one for doing builds, one for export via HTTP:
# mkdir /srv/centos-atomic # cd /srv/centos-atomic # git clone https://github.com/CentOS/sig-atomic-buildscripts -b downstream # mkdir build-repo # ostree --repo=build-repo init --mode=bare-user # mkdir repo # ostree --repo=repo init --mode=archive
We'll also want to cache downloaded RPMs:
# mkdir cache
rpm-ostree compose tree
This program takes as input a manifest file that describes the target system, and commits the result to an OSTree repository.
If you're doing this multiple times, it's strongly recommended to create a cache directory:
# rpm-ostree compose tree --unified-core --cachedir=cache --repo=/srv/centos-atomic/build-repo sig-atomic-buildscripts/centos-atomic-host.json
This will download RPMs from the referenced repos, and commit the result to the
OSTree repository, using the ref named by
Once we have that commit, let's export it:
# ostree --repo=repo pull-local build-repo centos-atomic-host/7/x86_64/standard
You can tell client systems to rebase to it by combining
ostree remote add,
rpm-ostree rebase on the client side.