Misc doc tweaks/cleanups
- Link to osbuild blog - Drop CentOS 7 stuff - clarify goals a bit
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Colin Walters
OpenShift Merge Robot
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@ -17,7 +17,13 @@ OSTree commits *also* want to generate bootable disk images, and rpm-ostree
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has nothing to do with that.
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One example higher level tool that takes care of both OSTree commit generation
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and bootable disk images is [coreos-assembler](https://github.com/coreos/coreos-assembler).
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and bootable disk images is [coreos-assembler](https://github.com/coreos/coreos-assembler);
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it is strongly oriented towards "CoreOS-like" systems which include rpm-ostree
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and Ignition.
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The [osbuild](https://www.osbuild.org/) project has some support for
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rpm-ostree based systems. See [this blog entry](https://www.osbuild.org/news/2020-06-01-how-to-ostree-anaconda.html)
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for example.
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## Background on managing an OSTree repository
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@ -27,60 +33,39 @@ of the OSTree manual:
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- [buildsystem-and-repos](https://ostreedev.github.io/ostree/buildsystem-and-repos/)
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- [repository-management](https://ostreedev.github.io/ostree/repository-management/)
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## Generating OSTree commits from a CentOS base
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## Generating OSTree commits in a container
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First, you'll need a copy of `rpm-ostree`. The current recommendation is to use
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a privileged container, but you can also install `rpm-ostree` directly to a
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physical or virtual machine.
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`rpm-ostree compose tree` runs well in an unprivileged (or "run as root")
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podman container. You can also use other container tools, they are just less
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frequently tested.
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It's included in the package collection for Fedora, and there
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are [CentOS Core packages](http://buildlogs.centos.org/centos/7/atomic/x86_64/Packages/) as
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well as [bleeding edge CentOS builds](https://ci.centos.org/job/atomic-rdgo-centos7/).
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You can also directly install `rpm-ostree` on a traditional `yum/rpm` based
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virtual (or physical) machine - it won't affect your host. However, containers
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are encouraged.
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You can create a privileged container with e.g. `podman` via: `podman run
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--privileged registry.fedoraproject.org/fedora:27 ...`. However you create the
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environment, run `yum -y install rpm-ostree`.
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## Choosing a base config
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A good first thing to try would be using
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the
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[CentOS Atomic Host](https://github.com/CentOS/sig-atomic-buildscripts/tree/downstream) metadata
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to generate a custom host.
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Currently, rpm-ostree is fairly coupled to the Fedora project. We are open to supporting
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other distributions however.
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One time setup, where we clone the git repository, then make two OSTree repos,
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one for doing builds, one for export via HTTP:
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Example base rpm-ostree "manifest repositories" are:
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```
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# mkdir /srv/centos-atomic
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# cd /srv/centos-atomic
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# git clone https://github.com/CentOS/sig-atomic-buildscripts -b downstream
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# mkdir build-repo
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# ostree --repo=build-repo init --mode=bare-user
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# mkdir repo
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# ostree --repo=repo init --mode=archive
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```
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We'll also want to cache downloaded RPMs:
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```
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# mkdir cache
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```
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- [Silverblue](https://pagure.io/workstation-ostree-config)
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- [IoT](https://pagure.io/fedora-iot/ostree)
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- [Fedora CoreOS](https://github.com/coreos/fedora-coreos-config/)
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## Running `rpm-ostree compose tree`
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This program takes as input a manifest file that describes the target system,
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and commits the result to an OSTree repository.
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The input format is a JSON "treefile". See examples in
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`api-doc/treefile-examples`. More real-world examples include the manifest
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for
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[Fedora Atomic](https://pagure.io/fedora-atomic/blob/master/f/fedora-atomic-host.json) and
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[CentOS Atomic](https://github.com/CentOS/sig-atomic-buildscripts/blob/downstream/centos-atomic-host.json).
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The input format is a YAML (or JSON) "treefile".
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If you're doing this multiple times, it's strongly recommended to create a cache
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directory:
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```
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# rpm-ostree compose tree --unified-core --cachedir=cache --repo=/srv/centos-atomic/build-repo sig-atomic-buildscripts/centos-atomic-host.json
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# rpm-ostree compose tree --unified-core --cachedir=cache --repo=/srv/repo /path/to/manifest.yaml
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```
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This will download RPMs from the referenced repos, and commit the result to the
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@ -89,7 +74,7 @@ OSTree repository, using the ref named by `ref`.
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Once we have that commit, let's export it:
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```
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# ostree --repo=repo pull-local build-repo centos-atomic-host/7/x86_64/standard
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# ostree --repo=repo pull-local build-repo exampleos/8/x86_64/stable
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```
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You can tell client systems to rebase to it by combining `ostree remote add`,
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@ -97,8 +82,6 @@ and `rpm-ostree rebase` on the client side.
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## More information
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* [run-treecompose script from FAHC](https://pagure.io/fedora-atomic-host-continuous/blob/2f1214c9ff35e55ec111db86be96e14d4b6040d6/f/centos-ci/run-treecompose)
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* [Build Your Own Atomic](https://github.com/jasonbrooks/byo-atomic)
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* [Build Your Own Atomic Image, Updated](http://www.projectatomic.io/blog/2014/08/build-your-own-atomic-centos-or-fedora/)
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* [Creating custom Atomic trees, images, and installers, part 1](http://developerblog.redhat.com/2015/01/08/creating-custom-atomic-trees-images-and-installers-part-1/)
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* [Creating custom Atomic trees, images, and installers, part 2](http://developerblog.redhat.com/2015/01/15/creating-custom-atomic-trees-images-and-installers-part-2/)
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- https://www.osbuild.org/news/2020-06-01-how-to-ostree-anaconda.html
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- https://github.com/coreos/coreos-assembler
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@ -40,9 +40,9 @@ many of the benefits of both together.
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**Features:**
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- Transactional, background image-based (versioned/checksummed) upgrades
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- OS rollback without affecting user data (`/usr` but not `/etc`, `/var`) via libostree
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- OS rollback without affecting user data (`/usr`, `/etc` but not `/var`) via libostree
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- Client-side package layering (and overrides)
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- Easily make your own: `rpm-ostree compose tree` and [CoreOS Assembler](https://github.com/coreos/coreos-assembler)
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- Easily make your own derivatives
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## Projects using rpm-ostree
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@ -61,16 +61,26 @@ Originally, it was productized as part of [Project Atomic](http://www.projectato
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## Getting started
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If you want to try the system as a user, we recommend
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[Fedora CoreOS](https://getfedora.org/en/coreos). If you are interested in
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assembling your own systems, see [compose server](compose-server.md).
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If you want to try the system as a user, see the main [Fedora website](https://getfedora.org/)
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which has several versions that use rpm-ostree, including Silverblue, IoT and CoreOS.
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If you are interested in assembling your own systems, see [compose server](compose-server.md).
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## Why?
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Package systems such as apt and yum are highly prevalent in Linux-based
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operating systems. The core premise of rpm-ostree is that image-based updates
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operating systems. They offer a lot of flexiblity, but have many failure
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modes.
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The core premise of rpm-ostree is that offline transactional image-based updates
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should be the default. This provides a high degree of predictability and
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resiliency. However, where rpm-ostree is fairly unique in the ecosystem is
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resiliency. The operating system vendor can focus a lot of effort
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on testing the "base images" as a unit.
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Further, image based updates simply work better at scale. For "IoT" style devices
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it's very inefficient to have each machine perform dependency resolution,
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run package scripts etc. And the same is true for many server datacenter
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use cases.
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Where rpm-ostree is fairly unique in the ecosystem is
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supporting client-side package layering and overrides; deeply integrating RPM
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as an (optional) layer on top of OSTree.
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@ -89,6 +99,10 @@ installing and updating client-side packages constructs a new filesystem root,
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it does not by default affect your booted root. This preserves the "image"
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nature of the system.
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By its nature as a hybrid image/package system, rpm-ostree is intended
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to span nearly all use cases of current package systems *and* image
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systems.
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## Why would I want to use it?
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One major feature rpm-ostree has over traditional package management
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@ -98,14 +112,6 @@ is atomic upgrade/rollback. It supports a model where an OS vendor
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images", and client systems can replicate those, and possibly layer on
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additional packages.
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rpm-ostree is a core part of the [Project Atomic](http://www.projectatomic.io/)
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effort, which uses rpm-ostree to provide a minimal host for
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Docker formatted Linux containers.
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We expect most users will be interested in rpm-ostree on the client
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side, using it to replicate a base system, and possibly layer on
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additional packages, and use containers for applications.
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## Why not implement these changes in an existing package manager?
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The [OSTree related projects](https://coreos.github.io/ostree/related-projects/)
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