Colin Walters
6ffcb24d22
When reworking the ostree core [to use O_TMPFILE](https://github.com/ostreedev/ostree/pull/369), I hit an issue in the way the untrusted delta codepath ends up trying to re-open the file to checksum it. That's not possible with `O_TMPFILE` since the fd (which we opened `O_WRONLY`) is the only accessible reference to the content. Fix this by changing the delta processing code to update a checksum as we're doing writes, which is also faster, and ends up simplifying the code as well. What would be an even larger simplification here is if we e.g. used a separate thread calling `write_object()` or something like that; the main issue I see there is somehow bridging the fact that function wants a `GInputStream*` but the delta code is generating stream of writes. Closes: #392 Approved by: jlebon
OSTree
New! See the docs online at Read The Docs (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.
OSTree is like git in that it checksums individual files and has a content-addressed-object store. It's unlike git in that it "checks out" the files via hardlinks, and they should thus be immutable. Therefore, another way to think of OSTree is that it's just a more polished version of Linux VServer hardlinks.
Features:
- Atomic upgrades and rollback for the system
- Replicating content incrementally over HTTP via GPG signatures and "pinned TLS" support
- Support for parallel installing more than just 2 bootable roots
- Binary history on the server side (and client)
- Introspectable shared library API for build and deployment systems
This last point is important - you should think of the OSTree command line as effectively a "demo" for the shared library. The intent is that package managers, system upgrade tools, container build tools and the like use OSTree as a "deduplicating hardlink store".
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. This is appropriate for "fixed purpose" systems. There is in progress work for more sophisticated hybrid models, deeply integrating the RPM packaging with OSTree.
Project Atomic uses rpm-ostree to provide a minimal host for Docker formatted Linux containers. Replicating a base immutable OS, then using Docker for applications meshes together two different tools with different tradeoffs.
flatpak 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
New! See the docs online at Read The Docs (OSTree)
Some more information is available on the old wiki page: https://wiki.gnome.org/Projects/OSTree
Contributing
See Contributing.