Colin Walters
5929ce9e0e
A fast way to generate new OSTree content using an existing tree is to checkout (as hard links), add/replace files, then call `ostree_repo_scan_hardlinks()`, then commit. But `ostree_repo_scan_hardlinks()` scans the entire repo, which can be slow if you have a lot of content. All we really need is a mapping of (device,inode) -> checksum just for the objects we checked out, then use that mapping for commits. This patch adds API so that callers can create a mapping via `ostree_repo_devino_cache_new()`, then pass it to `ostree_repo_checkout_tree_at()` which will populate it, and then `ostree_repo_write_directory_to_mtree()` can consume it. I plan to use this in rpm-ostree for package layering work. Notes: - The old `ostree_repo_scan_hardlinks()` API still works. - I tweaked the cache to be a set with the checksum colocated with the key, to avoid a separate malloc block per entry. https://github.com/GNOME/ostree/pull/167
OSTree
OSTree is a tool that combines a "git-like" model for committing and downloading bootable filesystem trees, along with a layer for deploying them and managing the bootloader configuration.
Traditional package managers (dpkg/rpm) build filesystem trees on the client side. In contrast, the primary focus of OSTree is on replicating trees composed on a server.
Features:
- Atomic upgrades and rollback
- GPG signatures and "pinned TLS" support
- Support for parallel installing more than just 2 bootable roots
- Binary history on the server side
- Introspectable shared library API for build and deployment systems
Projects using OSTree
rpm-ostree is a tool that uses OSTree as a shared library, and supports committing RPMs into an OSTree repository, and deploying them on the client.
Project Atomic uses rpm-ostree to provide a minimal host for Docker formatted Linux containers.
xdg-app uses OSTree for desktop application containers.
GNOME Continuous is a custom build system designed for OSTree, using OpenEmbedded in concert with a custom build system to do continuous delivery from hundreds of git repositories.
Building
Releases are available as GPG signed git tags, and most recent versions support extended validation using git-evtag.
However, in order to build from a git clone, you must update the submodules. If you're packaging OSTree and want a tarball, I recommend using a "recursive git archive" script. There are several available online; this code in OSTree is an example.
Once you have a git clone or recursive archive, building is the same as almost every autotools project:
env NOCONFIGURE=1 ./autogen.sh
./configure --prefix=...
make
make install DESTDIR=/path/to/dest
More documentation
Some more information is available on the old wiki page: https://wiki.gnome.org/Projects/OSTree
The intent is for that wiki page content to be migrated into Markdown in this git repository.
Contributing
See Contributing.